Title of Invention	"NON LINEAR MICROWAVE PULSED POWER AMPLIFIER AND METHOD FOR AMPLIFYING MICROWAVE SIGNAL"
Abstract	A non linear microwave pulsed power amplifier and a method for oscillation free pulsed microwave power output with compressed gain are disclosed. The amplifier comprises a first input matching network (101) configured for receiving and conditioning a microwave signal, a first nonlinear power device (102) connected to said first input matching network for amplifying the conditioned microwave signal from said first input matching network, a first output power matching network (103) connected to said first nonlinear power device for transferring the amplified microwave signal with desired power, from said first nonlinear power device to an isolator (104), a second input matching network (105) configured for receiving and conditioning output signal from said isolator, a plurality of second nonlinear power devices (107) connected in parallel to each other, with said splitter (106) for amplifying the microwave signals from the splitter, a combiner (108) connected to said plurality of second nonlinear power devices for combining the output power of the amplified microwave signals, a second output power matching network (109) connected to the combiner for yielding optimum output power of the amplified microwave signal, an electronic power conditioner (110) configured for supplying power to said first nonlinear power device and said plurality of second nonlinear power devices.

Title of Invention

"NON LINEAR MICROWAVE PULSED POWER AMPLIFIER AND METHOD FOR AMPLIFYING MICROWAVE SIGNAL"

Abstract

A non linear microwave pulsed power amplifier and a method for oscillation free pulsed microwave power output with compressed gain are disclosed. The amplifier comprises a first input matching network (101) configured for receiving and conditioning a microwave signal, a first nonlinear power device (102) connected to said first input matching network for amplifying the conditioned microwave signal from said first input matching network, a first output power matching network (103) connected to said first nonlinear power device for transferring the amplified microwave signal with desired power, from said first nonlinear power device to an isolator (104), a second input matching network (105) configured for receiving and conditioning output signal from said isolator, a plurality of second nonlinear power devices (107) connected in parallel to each other, with said splitter (106) for amplifying the microwave signals from the splitter, a combiner (108) connected to said plurality of second nonlinear power devices for combining the output power of the amplified microwave signals, a second output power matching network (109) connected to the combiner for yielding optimum output power of the amplified microwave signal, an electronic power conditioner (110) configured for supplying power to said first nonlinear power device and said plurality of second nonlinear power devices.

Full Text	NON LINEAR MICROWAVE PULSED POWER AMPLIFIER AND METHOD FOR AMPLIFYING MICROWAVE SIGNAL FIELD OF INVENTION The present invention generally relates to a power amplifier and more specifically to a non linear microwave pulsed power amplifier and a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain. BACKGROUND OF INVENTION Conventional Solid State Power Amplifier (SSPA) is implemented using small signal scattering parameters and power stages associated to the SSPA are implemented using internally matched devices. The internally matched device based SSPA cannot let study the device behavior at the saturation region. This type of conventional SSPA based on inbuilt matched configuration requires practical optimization which is non-repetitive and time consuming. The reference "Microwave power amplifier", CA 02298317, illustrates a microwave amplifier for non-linear distortion compensation function. The reference "Microwave power amplifier", CA 2073790 describes solid state microwave power amplifier modules based on LTCC. The reference "Solid State Microwave power amplifier module", CA 2088624 depicts L band BJT based microwave power amplifier with a dynamically efficient biasing arrangement. The reference "Microwave Power Amplifier", US 676265, expresses wave guide power Amplifier. None of the above references teach implementation of a non linear microwave pulsed power amplifier for oscillation free pulsed microwave power output with compressed gain. The conventional implementation technique of the microwave SSPA can not support single tone voltage dependent nonlinear design when design demands assured compressed or saturated output power level, compressed gain, power added efficiency, AM/PM (Amplitude Modulation to Phase Modulation) value at specific drain to source voltage level, multi tone study for definite harmonic suppression, suppression of intermodulation products, package study, analysis of the complete system and the impact of enclosure on the electrical performances. SSPA is used to boost the input signal at the microwave frequency. In the present days, most of the systems have very stringent specifications and thereby the non-linear study is essential to characterize the non-linear behavior of the system. Package selection is also critical, since at the microwave frequency, the enclosure plays a significant role and it can perturb the original performances of the circuit or system. Non-linear study and implementation is carried out using nonlinear components of the power devices to get compressed output power, compressed gain etc. Thus, there arises a need for a non linear microwave pulsed power amplifier for oscillation free pulsed microwave power output with compressed gain and a method of amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain. OBJECT OF INVENTION An object of the present invention is to provide a non linear microwave pulsed power amplifier (NLMPPA) to yield an oscillation free optimum pulsed microwave power output with compressed gain and to mount the NLMPPA in a package to establish a resonant free environment. Another object of the present invention is to provide a method for amplifying microwave signal to yield an oscillation free optimum pulsed microwave power output with compressed gain. SUMMARY OF INVENTION According to one aspect, the present invention, which achieves the objectives, relates to a non linear microwave pulsed power amplifier (NLMPPA) for oscillation free optimum pulsed microwave power output with compressed gain comprising a first input matching network configured for receiving and conditioning a microwave signal. A first nonlinear power device connected to said first input matching network for amplifying the conditioned microwave signal from said first input matching network. A first output power matching network connected to said first nonlinear power device for transferring the amplified microwave signal with desired power, from said first nonlinear power device to an isolator. A second input matching network configured for receiving and conditioning output signal from said isolator. A plurality of second nonlinear power devices connected in parallel to each other, with a splitter for amplifying the microwave signals from the splitter, the splitter being connected to the second input matching network. A combiner connected to said plurality of second nonlinear power devices for combining the output power of the amplified microwave signals. A second output power matching network connected to the combiner for yielding optimum output power of the amplified microwave signal. An electronic power conditioner configured for supplying power to said first nonlinear power device and said plurality of second nonlinear power devices. The first nonlinear power device and the plurality of second nonlinear power devices are operated at reduced drain to source voltage range of 9V±0.2V and a gate to drain voltage range of -1.2V to -1.34V. The NLMPPA is mounted in a package to establish a resonant free environment. The isolator absorbs any reflection due to improper matching between the first output power matching network and the second input matching network. The power splitter splits its input power equally. The combiner combines the amplified output power coming from both the nonlinear power devices. According to another aspect, the present invention, which achieves the objectives, relates to a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain comprising the steps of conditioning the microwave signal and filtering the dc signal at the input. A first nonlinear power device and a plurality of second nonlinear power devices are biased with low drain to source voltage. The first nonlinear power device and the plurality of second nonlinear power devices are operated in non linear region. Any reflection is absorbed by the isolator due to improper matching between the first output power matching network and the second input matching network. The amplified microwave output power from the first noiilinear power device equally splitted and transferred to said plurality of second nonlinear power devices. The output power from said plurality of second nonlinear power devices is combined and a resonance free package is provided to amplify microwave signal. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be discussed in greater detail with reference to the accompanying Figures. Fig. 1 illustrates a block diagram of a non linear microwave pulsed power amplifier, in accordance with an exemplary embodiment of the present invention; Fig. 2 illustrates a power added efficiency contour and a delivered power contour of a first nonlinear power device, in accordance with an exemplary embodiment of the present invention; Fig. 3 illustrates a load reflection co-efficient of the first nonlinear power device, in accordance with an exemplary embodiment of the present invention; Fig. 4 illustrates a power added efficiency contour and a delivered power contour of second nonlinear power devices, in accordance with an exemplary embodiment of the present invention; Fig. 5 illustrates a load reflection co-efficient of the second nonlinear power devices, in accordance with an exemplary embodiment of the present invention; Fig. 6 illustrates output power and gain of the microwave nonlinear power devices at different frequencies, in accordance with an exemplary embodiment of the present invention; Fig. 7 illustrates output power and gain of the non linear microwave pulsed power amplifier at different drain to source voltages, in accordance with an exemplary embodiment of the present invention; Fig. 8 illustrates Eigen mode electric field pattern of package, in accordance with an exemplary embodiment of the present invention; Fig. 9 illustrates coupling of the package at different frequencies, in accordance with an exemplary embodiment of the present invention; and Fig. 10 illustrates a flowchart depicting a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain, in accordance with another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring to Fig. 1, a block diagram of a non linear microwave pulsed power amplifier (NLMPPA) is illustrated in accordance with an exemplary embodiment of the present invention. The NLMPPA (100) is implemented with a first input matching network (101), a first nonlinear power device (102), a first output power matching network (103), an isolator (104), a second input matching network (105), a splitter (106), plurality of second nonlinear power devices (107), a combiner (108), a second output matching network (109) and an Electronic power conditioner (110). The first input matching network (101) receives the microwave input signal (RF In) that is to be amplified. The first input matching network consists of scattering parameter (s-parameter) input block of inbuilt matching circuit of first nonlinear power device as well as the distributed micro strip components. The input signal passes through dc blocking capacitor, which allows the high frequency microwave signal to pass through it and blocks the dc signal. This capacitor is used at the input of the matching circuits. Likewise the high impedance line is connected in parallel line to the main transmission line to allow the dc signal for gate path and also to block the microwave signal by providing high impedance for the microwave signal. The nonlinear first nonlinear power device (102) receives the nriicrowave signal, for instance, 22.3 dBm and amplifies this signal. The first nonlinear power device is biased at the continuous gate to drain voltage of -1.2V and the drain to source voltage of 9V±0.2V. The extrinsic inductances and capacitances are used as package parasitics at the gate, drain and source ends. The amplified signal from the first nonlinear power device is fed to the first output power matching network (103). The first output power rtiatching network consists of s-parameter output block of inbuilt matching circuit of device as well as the distributed micro strip components connected at the output. The output signal passes through dc blocking capacitor and a high impedance line is connected in parallel to the main transmission line. ^ The isolator (104) is connected in between the first output power matching network (103) and the second input matching network (105). The isolator absorbs any reflection due to improper matching between the first output power matching network and the second input matching network. The output of the second input matching network is connected to the splitter. The second nonlinear power devices (107) are connected in parallel with the splitter (106) which feeds the second nonlinear power devices. The output of the second nonlinear power devices is transferred to the second output power matching network (109) through the combiner (108). The combiner combines the amplified output power coming from both the second nonlinear power devices (107) and feeds the second output matching network. The second input matching network (105) receives the microwave input signal from the isolator output, which is to be further amplified. The second input matching network also consists of s-parameter input block of inbuilt matching circuit of second nonlinear power device (107) as well as the distributed micro strip components. The dc blocking capacitor is used at the input of the matching network and high impedance line is connected at gate side in parallel to the main transmission line. The power splitter (106) splits its input power equally. The combiner (108) combines the amplified output power coming from both the nonlinear power devices (107). The power of the amplified microwave signal from the first nonlinear power device is split into two equal halves by the splitter and the power of the amplified microwave signals from the plurality of second nonlinear power devices are combined by the combiner. Both the nonlinear second nonlinear power devices (107) receive microwave signal, for instance, of 33.1 dBm at the second input matching network (105), and amplify this signal to 12 watts (RF Out) at the output of the second output power matching network (109). The second nonlinear power devices are biased at gate to drain voltage of -1.34V and drain to source voltage of 9V±0.2V. The extrinsic inductances and capacitances are used as package parasitics at the gate, drain and source ends of the second nonlinear power devices. The first nonlinear power device and the plurality of second nonlinear power devices are biased by the electronic power conditioner with a drain to source voltage range of 9V±0.2V and a gate to drain voltage range of -1.2V to -1.34V. The second output matching network (109) consists of s-parameter output block of inbuilt matching circuit of second nonlinear power devices as well as the distributed microstrip lines connected at the output of the combiner (108). The output signal passes through dc blocking capacitor and a high impedance line is connected at drain side in parallel line to the main transmission line. The gate and drain voltages for both the first nonlinear power devices (102) and the nonlinear second power (107) are derived from Electronic power controller (110). The first nonlinear power device and the second nonlinear power devices are microwave power devices, which are capable of amplifying microwave signals in the frequency range of 5350 ± 125 MHz. The output power of the microwave at the second power devices is 12 watts with a gain of 18.5 dB. An output power of 12 watts with a gain of 18.5 dB is achieved with the NLMPPA. The operation of microwave nonlinear power devices at reduced voltage increases the device reliability by providing less stress on the device required to be operated for the mission lifetime. The use of lower drain to source voltage increases the reliability of the NLMPPA. Proper implementation of the nonlinear NLMPPA with specific drain to source voltage (Vds) is prime requirement for space borne NLMPPA design. Here the NLMPPA is designed with a proper value of Vds and efforts are made to reduce the stress on devices of NLMPPA and thereby increasing the reliability of the NLMPPA. So the study of voltage dependent output powers at the constant frequency is carried out. The NLMPPA is mounted in a package having a length of 95.2mm, height of 5mm and width of 40 mm. The desired dimension of the package provides a resonant free environment for the NLMPPA at desired operating frequencies. Fig 2 illustrates a power added efficiency contour and a delivered power contour of the first nonlinear power device, in accordance with an exemplary embodiment of the present invention. The graph (201) shows the added efficiency and the graph (202) shows the delivered power. Similarly, in Fig 3, the load reflection co-efficient of the first nonlinear power device is illustrated, in accordance with an exemplary embodiment of the present invention. Fig 4 illustrates power added efficiency contour and delivered power contour of the second nonlinear power devices, in accordance with an exemplary embodiment of the present invention. The graph (401) shows the added efficiency and the graph (402) shows the delivered power. Similarly, in Fig 5, the load reflection co-efficient of the second nonlinear power device is illustrated, in accordance with an exemplary embodiment of the present invention. Fig 6 illustrates the integrated output power and gain of the NLMPPA at different frequencies, in accordance with an exemplary embodiment of the present invention. The graphs (601 & 604) show the power and gain at 5.35 GHz respectively. The graphs (602 & 605) show the power and gain at 5.225 GHz respectively. The graphs (603 & 606) show the power and gain at 5.475 GHz respectively. Fig 7 illustrates the integrated output power and gain of the NLMPPA at different drain to source voltages, in accordance with an exemplary embodiment of the present invention. The graphs (701 & 704) show the power and gain at drain to source voltage of 10V respectively. The graphs (702 & 705) show the power and gain at drain to source voltage of 9V respectively. The graphs (703 & 706) show the power and gain at drain to source voltage of 8V respectively. Fig. 8 illustrates Eigen mode electric field pattern of package for NLMPPA with a dimension of 95.2mm as length, 5mm as height and 40 mm as width. Fig. 9 illustrates coupling of the package at different frequencies, in accordance with an exemplary embodiment of the present invention. The point 1 shown in graph pertains to a frequency value of 2.73 GHz and a coupling value of -15.01 dB. The point 2 shown in graph pertains to a frequency value of 3.18 GHz and a coupling value of -17.05 dB. The point 3 shown in graph pertains to a frequency value of 4.17 GHz and a coupling value of -16.36 dB. The point 4 shown in graph pertains to a frequency value of 7.08 GHz and a coupling value of -15.52 dB. The point 5 shown in graph pertains to a frequency value of 7.30 GHz and a coupling value of-66.49 dB. Referring to Fig 10, a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain is illustrated, in accordance with another embodiment of the present invention. The method of amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain may be achieved by conditioning the microwave signal and filtering the dc signal at the input (1001); biasing a first nonlinear power device and a plurality of second nonlinear power devices with low drain to source voltage (1002); operating said first nonlinear power device and said plurality of second nonlinear power devices in non linear region (1003); absorbing any reflection by the isolator due to improper matching between first output power matching network and second input matching network (1004); splitting and transferring the amplified microwave output power from said first nonlinear power device equally to said plurality of second nonlinear power devices (1005); combining the output power from said plurality of second nonlinear power devices (1006); and providing a resonance free package to amplify microwave signal (1007). The microwave non linear pulsed power amplifier (NLMPPA) module is implemented for the frequency range of 5350 ± 125 MHz with 22 microsecond pulse width and 7.5% duty cycle. The NLMPPA (100) consists of RF (Radio Frequency) section and EPC (Electronic Power Condition). The DC voltages required for biasing the device are derived from EPC (110), which converts the 70-volt raw bus voltage. The heart of EPC is multi output switch mode power supply having pulsed as well as continuous outputs. Positive pulsed voltages are required for drain biasing while negative cw voltages for gate biasing. The pulsed supplies of 9V are applied to all drains of the devices. The continuous supply of-5V is sampled and applied to the respective gates of the devices. While biasing the MESFET (MEtal Semiconductor Field Effect Transistor) devices, the most negative gate voltages are applied prior to application of drain voltage to avoid the damage of the device. The NLMPPA study is done using nonlinear power devices (102,107) to get required power of 12 Watt output power from an input power of 22.3 dBm with 18.5 dB gain. Non-linear study is carried out using nonlinear models of the power devices to get compressed output power of 12Watt with Vds of 9 volt. The study is based on Harmonic Balance (HB) technique in which harmonics up to third order is considered. Single carrier non-linear study is carried out at the fundamental frequency of 5.35 GHz using load pull technique to find out optimum load reflection coefficient to maximize the output power. The non-linear output power and gain has been studied over the range of Vds and for swept RF input power from 14 to 24 dBm. The individual stages of NLMPPA have been designed in the non-linear mode and momentum study has also been carried out for input and output matching circuit layouts. During the study five layers (Ti-W-Au-Cu-Ni-Au) metallized alumina substrate with thickness of 0.635 mm, dielectric constant of 9.9, dielectric loss tangent of 0.0007 and metallization thickness of 8-13 Mm has been used. The five-layer metallized alumina substrate is used considering all the issues like inter metal diffusion, solderability, frequency of operation and maximum temperature limits. Performance study is carried out for the individual stages and subsequently for the integrated two-stages over the frequency of 5.35 GHz, ±125 MHz. The NLMPPA is fabricated with metallized substrate (Ti-W-Au-Cu-Ni-Au) with thickness of 0.635 mm, dielectric constant of 9.9, dielectric loss tangent of 0.0007 and metallization thickness of 8-13 \|jm. The package (800) illustrated in Fig 8 is required for the NLMPPA assemble which provides environmental and electromagnetic protection. At high frequency, wavelength decreases and package (800) electrical size increases i.e. the package becomes electrically large and a number of undesirable parasitic effects degrade the device performance. Initially the bare package of aluminum alloy "6061T" is analyzed for the dimensions a= 95.2mm, b=5mm, c=40mm, where a, b and c are length, height and width respectively. The package provides a resonant free environment for the microwave signals in the frequency range of 5350 D 125 MHz. The non linear microwave power amplifier assembly is housed in the package (800), which provides a resonant free environment for the microwave signals in the frequency range of 5350 D 125 MHz. The resonance frequency of cavity (package) is given as: mnp 27r^/\|j^ '^mTt^ V a ; ^nn^ 2 / N2 + V D y + The material undercut and elevation are incorporated for the active device alignment. The package assembled with matching circuits fabricated on the five-layer alumina substrate of 13 micron metallized thickness was analyzed considering other components such as hermetically packaged device, isolator, feed-throughs, connectors, and screws. Table-1 below shows the results of theoretical and Eigen mode analysis for the unloaded and loaded package. The resonant mode frequencies of the assembled package are different from the bare package because of the consideration of carrier plates, feed-throughs, isolator, device enclosures and mounting screws. Table-1 Resonant Mode Bare Package Assembled package Analytical Frequency (GHz) Eigen- mode Frequency (GHz) Eigen- mode Frequency (GHz) Model 4.0676 4.0426 2.69 Mode2 4.8983 4.9699 3.17 Mode3 6.0337 6.0432 4.21 Mode4 7.3338 7.2342 7.09 Similarly, table 2 below shows the test summary of NLMPPA Table 2 Parameters Specifications Achieved Results Frequency (MHz) 5350+125 5350+125 0/P Pulse Power (P2dB) 12W 14.4W Gain (G2dB) 18.5 dB 19.6 dB Gain Flatness (amb) ±0.5dB ±0.3dB Gain Flatness (over -5°C to +55°C) ±0.8dB ±0.7dB Pulse Width 20\|as 20.06 i^s Duty Cycle 7.5% 7.5% Rise Time 200 ns 37.6ns Fall Time 200 ns 77ns Droop 0.5 dB 0.12 dB Current 5.4 A (typ) 5.5 A Efficiency (EPC) - 70% Efficiency (NLMPD) ~ >28% Efficiency (Overall) - 19.6% The study on the (NLMPPA) (100) shows that compressed output power increases with increase of drain-to-source voltage and gain compression increases with decrease of drain-to-source voltage. It also shows the compressed output power (P2dB) of 12 watt at the input power of 22.3 dBm at the voltage of 9 V. The package (800) analysis of the NLMPPA module shows that the theoretical and Eigen mode resonant frequencies of the bare package have very good agreement with each other and all the resonant modes are appearing outside the frequency range of operation. The only mode which is appearing 200 MHz apart from the left corner frequency of operation is mode2. The field pattern of this mode shows a positive and a negative peak appearing just above the active devices, not on the matching circuits. The resonant mode frequencies of the assembled package are different from the bare one because of the consideration of carrier plates, feed-throughs, isolator, device enclosures and mounting screws. The loaded package analysis shows that below 5 GHz coupling is more compared to bare package, but it can be neglected, since it is out of the required frequency band. The measured test result shows that worst case output gain and power variation over the extreme temperature limits are within ±0.7dB. The C-band NLMPPA fabricated on five layer substrate validates most of the design specifications and also shows very good correlation between studied and measured results. Package has been analyzed for bare and assembled package to see the cavity effect of the package. The adaptation of pulse concept is to reduce the overall size, weight, and dc power consumption of NLMPPA and thereby reduces the thermal stresses on the RF system as well as satellite power-generating unit. The NLMPPA modules will be used for Radar Imaging Satellite (RISAT) as a part of transmit chain of 288 pairs of TR-Modules, which are going to be placed on the backside of the radiating panel of the active phased array antenna. WE CLAIM: 1. A non linear microwave pulsed power amplifier for oscillation free pulsed microwave power output with compressed gain, comprising: a first input matching network (101) configured for receiving and conditioning a microwave signal; a first nonlinear power device (102) connected to said first input matching network for amplifying the conditioned microwave signal from said first input matching network; a first output power matching network (103) connected to said first nonlinear power device for transferring the amplified microwave signal with desired power, from said first nonlinear power device to an isolator (104); a second input matching network (105) configured for receiving and conditioning output signal from said isolator; a plurality of second nonlinear power devices (107) connected in parallel to each other, with said splitter (106) for amplifying the microwave signals from the splitter; a combiner (108) connected to said plurality of second nonlinear power devices for combining the output power of the amplified microwave signals; a second output power matching network (109) connected to the combiner for yielding optimum output power of the amplified microwave signal; and an electronic power conditioner (110) configured for supplying power to said first nonlinear power device and said plurality of second nonlinear power devices. 2. The amplifier as claimed in claim 1, wherein said first nonlinear power device, said splitter, said plurality of second nonlinear power devices and said combiner are connected in such a way that the power of the amplified microwave signal from said first nonlinear power device is split into two equal halves by said splitter and the power of the amplified microwave signals from said plurality of second nonlinear power devices are combined by the combiner. 3. The amplifier as claimed in claim 1, wherein said isolator absorbs any reflection due to improper matching between the first output power matching network and the second input matching network. 4. The amplifier as claimed in claim 1, wherein said first nonlinear power device and said plurality of second nonlinear power devices are biased by said electronic power conditioner with a drain to source voltage range of 9V±0.2V and a gate to drain voltage range of -1.2V to -1.34V. 5. The amplifier as claimed in claim 1, wherein said first input matching network and said second input matching network are capable of passing a desired microwave input signal through main transmission line by providing low impedance to said desired microwave signal and blocking said desired microwave input signal through parallel line by providing high impedance to said desired microwave signal. 6. The amplifier as claimed in claim 1, wherein said first input matching network and said second input matching network are capable of passing dc signal through parallel line by providing low impedance to said dc signal and blocking said dc signal through main transmission line by providing high impedance to said dc signal. 7. The amplifier as claimed in claim 1, wherein said first nonlinear power device and said plurality of second nonlinear power devices are microwave power amplifiers, which are capable of amplifying microwave signals in the frequency range of 5350 ± 125 MHz. 8. The amplifier as claimed in claim 1, wherein said output matching network is capable of passing a desired microwave output signal through main transmission line by providing low impedance to said desired microwave signal and blocking said desired microwave output signal through parallel line by providing high impedance to said desired microwave signal. 9. The amplifier as claimed in claim 1, wherein said output matching network is capable of passing dc signal through parallel line by providing low impedance to said dc signal and blocking said dc signal through main transmission line by providing high impedance to said dc signal. 10. The amplifier as claimed in claim 1, wherein the non linear microwave power amplifier assembly is housed in a package (800), which provides a resonant free environment for the microwave signals in the frequency range of 5350 ±125 MHz. 11. The amplifier as claimed in claim 1, wherein the non linear microwave power amplifier is fabricated with metallized substrate (Ti-W-Au-Cu-Ni-Au) with thickness of 0.635 mm, dielectric constant of 9.9, dielectric loss tangent of 0.0007 and metallization thickness of 8-13 pm. 12. The amplifier as claimed in claim 1, wherein the output power of the microwave at the second power devices is 12 watts with a gain of 18.5 dB. 13. A method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain, comprising the steps of. conditioning the microwave signal and filtering the dc signal at the input; biasing a first nonlinear power device and a plurality of second nonlinear power devices with low drain to source voltage; operating said first nonlinear power device and said plurality of second nonlinear power devices in non linear region; absorbing any reflection by the isolator due to improper matching between first output power matching network and second input matching network; splitting and transferring the amplified nnicrowave output power from said first nonlinear power device equally to said plurality of second nonlinear power devices; and combining the output power from said plurality of second nonlinear power devices and providing a resonance free package to amplify microwave signal.

Full Text

NON LINEAR MICROWAVE PULSED POWER AMPLIFIER AND METHOD FOR AMPLIFYING MICROWAVE SIGNAL
FIELD OF INVENTION
The present invention generally relates to a power amplifier and more specifically to a non linear microwave pulsed power amplifier and a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain.
BACKGROUND OF INVENTION
Conventional Solid State Power Amplifier (SSPA) is implemented using small signal scattering parameters and power stages associated to the SSPA are implemented using internally matched devices.
The internally matched device based SSPA cannot let study the device behavior at the saturation region. This type of conventional SSPA based on inbuilt matched configuration requires practical optimization which is non-repetitive and time consuming. The reference "Microwave power amplifier", CA 02298317, illustrates a microwave amplifier for non-linear distortion compensation function. The reference "Microwave power amplifier", CA 2073790 describes solid state microwave power amplifier modules based on LTCC. The reference "Solid State Microwave power amplifier module", CA 2088624 depicts L band BJT based microwave power amplifier with a dynamically efficient biasing arrangement. The reference "Microwave Power Amplifier", US 676265, expresses wave guide power Amplifier.
None of the above references teach implementation of a non linear microwave pulsed power amplifier for oscillation free pulsed microwave power output with compressed gain. The conventional implementation technique of the

microwave SSPA can not support single tone voltage dependent nonlinear design when design demands assured compressed or saturated output power level, compressed gain, power added efficiency, AM/PM (Amplitude Modulation to Phase Modulation) value at specific drain to source voltage level, multi tone study for definite harmonic suppression, suppression of intermodulation products, package study, analysis of the complete system and the impact of enclosure on the electrical performances.
SSPA is used to boost the input signal at the microwave frequency. In the present days, most of the systems have very stringent specifications and thereby the non-linear study is essential to characterize the non-linear behavior of the system. Package selection is also critical, since at the microwave frequency, the enclosure plays a significant role and it can perturb the original performances of the circuit or system. Non-linear study and implementation is carried out using nonlinear components of the power devices to get compressed output power, compressed gain etc. Thus, there arises a need for a non linear microwave pulsed power amplifier for oscillation free pulsed microwave power output with compressed gain and a method of amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain.
OBJECT OF INVENTION
An object of the present invention is to provide a non linear microwave pulsed power amplifier (NLMPPA) to yield an oscillation free optimum pulsed microwave power output with compressed gain and to mount the NLMPPA in a package to establish a resonant free environment.
Another object of the present invention is to provide a method for amplifying microwave signal to yield an oscillation free optimum pulsed microwave power output with compressed gain.

SUMMARY OF INVENTION
According to one aspect, the present invention, which achieves the objectives, relates to a non linear microwave pulsed power amplifier (NLMPPA) for oscillation free optimum pulsed microwave power output with compressed gain comprising a first input matching network configured for receiving and conditioning a microwave signal. A first nonlinear power device connected to said first input matching network for amplifying the conditioned microwave signal from said first input matching network. A first output power matching network connected to said first nonlinear power device for transferring the amplified microwave signal with desired power, from said first nonlinear power device to an isolator. A second input matching network configured for receiving and conditioning output signal from said isolator. A plurality of second nonlinear power devices connected in parallel to each other, with a splitter for amplifying the microwave signals from the splitter, the splitter being connected to the second input matching network. A combiner connected to said plurality of second nonlinear power devices for combining the output power of the amplified microwave signals. A second output power matching network connected to the combiner for yielding optimum output power of the amplified microwave signal. An electronic power conditioner configured for supplying power to said first nonlinear power device and said plurality of second nonlinear power devices. The first nonlinear power device and the plurality of second nonlinear power devices are operated at reduced drain to source voltage range of 9V±0.2V and a gate to drain voltage range of -1.2V to -1.34V. The NLMPPA is mounted in a package to establish a resonant free environment. The isolator absorbs any reflection due to improper matching between the first output power matching network and the second input matching network. The power splitter splits its input power equally. The combiner combines the amplified output power coming from both the nonlinear power devices.

According to another aspect, the present invention, which achieves the objectives, relates to a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain comprising the steps of conditioning the microwave signal and filtering the dc signal at the input. A first nonlinear power device and a plurality of second nonlinear power devices are biased with low drain to source voltage. The first nonlinear power device and the plurality of second nonlinear power devices are operated in non linear region. Any reflection is absorbed by the isolator due to improper matching between the first output power matching network and the second input matching network. The amplified microwave output power from the first noiilinear power device equally splitted and transferred to said plurality of second nonlinear power devices. The output power from said plurality of second nonlinear power devices is combined and a resonance free package is provided to amplify microwave signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be discussed in greater detail with reference to the accompanying Figures.
Fig. 1 illustrates a block diagram of a non linear microwave pulsed power amplifier, in accordance with an exemplary embodiment of the present invention;
Fig. 2 illustrates a power added efficiency contour and a delivered power contour of a first nonlinear power device, in accordance with an exemplary embodiment of the present invention;
Fig. 3 illustrates a load reflection co-efficient of the first nonlinear power device, in accordance with an exemplary embodiment of the present invention;

Fig. 4 illustrates a power added efficiency contour and a delivered power contour of second nonlinear power devices, in accordance with an exemplary embodiment of the present invention;
Fig. 5 illustrates a load reflection co-efficient of the second nonlinear power devices, in accordance with an exemplary embodiment of the present invention;
Fig. 6 illustrates output power and gain of the microwave nonlinear power devices at different frequencies, in accordance with an exemplary embodiment of the present invention;
Fig. 7 illustrates output power and gain of the non linear microwave pulsed power amplifier at different drain to source voltages, in accordance with an exemplary embodiment of the present invention;
Fig. 8 illustrates Eigen mode electric field pattern of package, in accordance with an exemplary embodiment of the present invention;
Fig. 9 illustrates coupling of the package at different frequencies, in accordance with an exemplary embodiment of the present invention; and
Fig. 10 illustrates a flowchart depicting a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain, in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Fig. 1, a block diagram of a non linear microwave pulsed power amplifier (NLMPPA) is illustrated in accordance with an exemplary

embodiment of the present invention. The NLMPPA (100) is implemented with a first input matching network (101), a first nonlinear power device (102), a first output power matching network (103), an isolator (104), a second input matching network (105), a splitter (106), plurality of second nonlinear power devices (107), a combiner (108), a second output matching network (109) and an Electronic power conditioner (110).
The first input matching network (101) receives the microwave input signal (RF In) that is to be amplified. The first input matching network consists of scattering parameter (s-parameter) input block of inbuilt matching circuit of first nonlinear power device as well as the distributed micro strip components. The input signal passes through dc blocking capacitor, which allows the high frequency microwave signal to pass through it and blocks the dc signal. This capacitor is used at the input of the matching circuits. Likewise the high impedance line is connected in parallel line to the main transmission line to allow the dc signal for gate path and also to block the microwave signal by providing high impedance for the microwave signal.
The nonlinear first nonlinear power device (102) receives the nriicrowave signal, for instance, 22.3 dBm and amplifies this signal. The first nonlinear power device is biased at the continuous gate to drain voltage of -1.2V and the drain to source voltage of 9V±0.2V. The extrinsic inductances and capacitances are used as package parasitics at the gate, drain and source ends.
The amplified signal from the first nonlinear power device is fed to the first
output power matching network (103). The first output power rtiatching network
consists of s-parameter output block of inbuilt matching circuit of device as well
as the distributed micro strip components connected at the output. The output
signal passes through dc blocking capacitor and a high impedance line is
connected in parallel to the main transmission line. ^

The isolator (104) is connected in between the first output power matching network (103) and the second input matching network (105). The isolator absorbs any reflection due to improper matching between the first output power matching network and the second input matching network. The output of the second input matching network is connected to the splitter. The second nonlinear power devices (107) are connected in parallel with the splitter (106) which feeds the second nonlinear power devices. The output of the second nonlinear power devices is transferred to the second output power matching network (109) through the combiner (108). The combiner combines the amplified output power coming from both the second nonlinear power devices (107) and feeds the second output matching network.
The second input matching network (105) receives the microwave input signal from the isolator output, which is to be further amplified. The second input matching network also consists of s-parameter input block of inbuilt matching circuit of second nonlinear power device (107) as well as the distributed micro strip components. The dc blocking capacitor is used at the input of the matching network and high impedance line is connected at gate side in parallel to the main transmission line.
The power splitter (106) splits its input power equally. The combiner (108) combines the amplified output power coming from both the nonlinear power devices (107). The power of the amplified microwave signal from the first nonlinear power device is split into two equal halves by the splitter and the power of the amplified microwave signals from the plurality of second nonlinear power devices are combined by the combiner.
Both the nonlinear second nonlinear power devices (107) receive microwave signal, for instance, of 33.1 dBm at the second input matching network (105), and amplify this signal to 12 watts (RF Out) at the output of the second output power matching network (109). The second nonlinear power

devices are biased at gate to drain voltage of -1.34V and drain to source voltage of 9V±0.2V. The extrinsic inductances and capacitances are used as package parasitics at the gate, drain and source ends of the second nonlinear power devices.
The first nonlinear power device and the plurality of second nonlinear power devices are biased by the electronic power conditioner with a drain to source voltage range of 9V±0.2V and a gate to drain voltage range of -1.2V to -1.34V.
The second output matching network (109) consists of s-parameter output block of inbuilt matching circuit of second nonlinear power devices as well as the distributed microstrip lines connected at the output of the combiner (108). The output signal passes through dc blocking capacitor and a high impedance line is connected at drain side in parallel line to the main transmission line.
The gate and drain voltages for both the first nonlinear power devices (102) and the nonlinear second power (107) are derived from Electronic power controller (110). The first nonlinear power device and the second nonlinear power devices are microwave power devices, which are capable of amplifying microwave signals in the frequency range of 5350 ± 125 MHz. The output power of the microwave at the second power devices is 12 watts with a gain of 18.5 dB. An output power of 12 watts with a gain of 18.5 dB is achieved with the NLMPPA.
The operation of microwave nonlinear power devices at reduced voltage increases the device reliability by providing less stress on the device required to be operated for the mission lifetime. The use of lower drain to source voltage increases the reliability of the NLMPPA. Proper implementation of the nonlinear NLMPPA with specific drain to source voltage (Vds) is prime requirement for space borne NLMPPA design. Here the NLMPPA is designed with a proper value of Vds and efforts are made to reduce the stress on devices of NLMPPA and

thereby increasing the reliability of the NLMPPA. So the study of voltage dependent output powers at the constant frequency is carried out. The NLMPPA is mounted in a package having a length of 95.2mm, height of 5mm and width of 40 mm. The desired dimension of the package provides a resonant free environment for the NLMPPA at desired operating frequencies.
Fig 2 illustrates a power added efficiency contour and a delivered power contour of the first nonlinear power device, in accordance with an exemplary embodiment of the present invention. The graph (201) shows the added efficiency and the graph (202) shows the delivered power. Similarly, in Fig 3, the load reflection co-efficient of the first nonlinear power device is illustrated, in accordance with an exemplary embodiment of the present invention.
Fig 4 illustrates power added efficiency contour and delivered power contour of the second nonlinear power devices, in accordance with an exemplary embodiment of the present invention. The graph (401) shows the added efficiency and the graph (402) shows the delivered power. Similarly, in Fig 5, the load reflection co-efficient of the second nonlinear power device is illustrated, in accordance with an exemplary embodiment of the present invention.
Fig 6 illustrates the integrated output power and gain of the NLMPPA at different frequencies, in accordance with an exemplary embodiment of the present invention. The graphs (601 & 604) show the power and gain at 5.35 GHz respectively. The graphs (602 & 605) show the power and gain at 5.225 GHz respectively. The graphs (603 & 606) show the power and gain at 5.475 GHz respectively.
Fig 7 illustrates the integrated output power and gain of the NLMPPA at different drain to source voltages, in accordance with an exemplary embodiment of the present invention. The graphs (701 & 704) show the power and gain at drain to source voltage of 10V respectively. The graphs (702 & 705) show the

power and gain at drain to source voltage of 9V respectively. The graphs (703 & 706) show the power and gain at drain to source voltage of 8V respectively.
Fig. 8 illustrates Eigen mode electric field pattern of package for NLMPPA with a dimension of 95.2mm as length, 5mm as height and 40 mm as width.
Fig. 9 illustrates coupling of the package at different frequencies, in accordance with an exemplary embodiment of the present invention. The point 1 shown in graph pertains to a frequency value of 2.73 GHz and a coupling value of -15.01 dB. The point 2 shown in graph pertains to a frequency value of 3.18 GHz and a coupling value of -17.05 dB. The point 3 shown in graph pertains to a frequency value of 4.17 GHz and a coupling value of -16.36 dB. The point 4 shown in graph pertains to a frequency value of 7.08 GHz and a coupling value of -15.52 dB. The point 5 shown in graph pertains to a frequency value of 7.30 GHz and a coupling value of-66.49 dB.
Referring to Fig 10, a method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain is illustrated, in accordance with another embodiment of the present invention. The method of amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain may be achieved by conditioning the microwave signal and filtering the dc signal at the input (1001); biasing a first nonlinear power device and a plurality of second nonlinear power devices with low drain to source voltage (1002); operating said first nonlinear power device and said plurality of second nonlinear power devices in non linear region (1003); absorbing any reflection by the isolator due to improper matching between first output power matching network and second input matching network (1004); splitting and transferring the amplified microwave output power from said first nonlinear power device equally to said plurality of second nonlinear power devices (1005); combining the output power from said plurality of second

nonlinear power devices (1006); and providing a resonance free package to amplify microwave signal (1007).
The microwave non linear pulsed power amplifier (NLMPPA) module is implemented for the frequency range of 5350 ± 125 MHz with 22 microsecond pulse width and 7.5% duty cycle. The NLMPPA (100) consists of RF (Radio Frequency) section and EPC (Electronic Power Condition). The DC voltages required for biasing the device are derived from EPC (110), which converts the 70-volt raw bus voltage. The heart of EPC is multi output switch mode power supply having pulsed as well as continuous outputs. Positive pulsed voltages are required for drain biasing while negative cw voltages for gate biasing. The pulsed supplies of 9V are applied to all drains of the devices. The continuous supply of-5V is sampled and applied to the respective gates of the devices. While biasing the MESFET (MEtal Semiconductor Field Effect Transistor) devices, the most negative gate voltages are applied prior to application of drain voltage to avoid the damage of the device.
The NLMPPA study is done using nonlinear power devices (102,107) to get required power of 12 Watt output power from an input power of 22.3 dBm with 18.5 dB gain. Non-linear study is carried out using nonlinear models of the power devices to get compressed output power of 12Watt with Vds of 9 volt. The study is based on Harmonic Balance (HB) technique in which harmonics up to third order is considered. Single carrier non-linear study is carried out at the fundamental frequency of 5.35 GHz using load pull technique to find out optimum load reflection coefficient to maximize the output power. The non-linear output power and gain has been studied over the range of Vds and for swept RF input power from 14 to 24 dBm. The individual stages of NLMPPA have been designed in the non-linear mode and momentum study has also been carried out for input and output matching circuit layouts. During the study five layers (Ti-W-Au-Cu-Ni-Au) metallized alumina substrate with thickness of 0.635 mm, dielectric constant of 9.9, dielectric loss tangent of 0.0007 and metallization thickness of 8-13 Mm

has been used. The five-layer metallized alumina substrate is used considering all the issues like inter metal diffusion, solderability, frequency of operation and maximum temperature limits. Performance study is carried out for the individual stages and subsequently for the integrated two-stages over the frequency of 5.35 GHz, ±125 MHz. The NLMPPA is fabricated with metallized substrate (Ti-W-Au-Cu-Ni-Au) with thickness of 0.635 mm, dielectric constant of 9.9, dielectric loss tangent of 0.0007 and metallization thickness of 8-13 |jm.
The package (800) illustrated in Fig 8 is required for the NLMPPA assemble which provides environmental and electromagnetic protection. At high frequency, wavelength decreases and package (800) electrical size increases i.e. the package becomes electrically large and a number of undesirable parasitic effects degrade the device performance. Initially the bare package of aluminum alloy "6061T" is analyzed for the dimensions a= 95.2mm, b=5mm, c=40mm, where a, b and c are length, height and width respectively. The package provides a resonant free environment for the microwave signals in the frequency range of 5350 D 125 MHz. The non linear microwave power amplifier assembly is housed in the package (800), which provides a resonant free environment for the microwave signals in the frequency range of 5350 D 125 MHz.
The resonance frequency of cavity (package) is given as:

mnp

27r^/|j^

'^mTt^
V a ;

^nn^
2 / N2
+
V D y

+

The material undercut and elevation are incorporated for the active device alignment. The package assembled with matching circuits fabricated on the five-layer alumina substrate of 13 micron metallized thickness was analyzed considering other components such as hermetically packaged device, isolator, feed-throughs, connectors, and screws.
Table-1 below shows the results of theoretical and Eigen mode analysis for the unloaded and loaded package. The resonant mode frequencies of the

assembled package are different from the bare package because of the consideration of carrier plates, feed-throughs, isolator, device enclosures and mounting screws.
Table-1

Resonant Mode Bare Package Assembled package

Analytical
Frequency
(GHz) Eigen- mode
Frequency
(GHz) Eigen- mode
Frequency
(GHz)
Model 4.0676 4.0426 2.69
Mode2 4.8983 4.9699 3.17
Mode3 6.0337 6.0432 4.21
Mode4 7.3338 7.2342 7.09
Similarly, table 2 below shows the test summary of NLMPPA
Table 2

Parameters Specifications Achieved Results
Frequency (MHz) 5350+125 5350+125
0/P Pulse Power
(P2dB) 12W 14.4W
Gain (G2dB) 18.5 dB 19.6 dB
Gain Flatness (amb) ±0.5dB ±0.3dB
Gain
Flatness (over -5°C to +55°C) ±0.8dB ±0.7dB
Pulse Width 20|as 20.06 i^s
Duty Cycle 7.5% 7.5%
Rise Time 200 ns 37.6ns
Fall Time 200 ns 77ns
Droop 0.5 dB 0.12 dB
Current 5.4 A (typ) 5.5 A
Efficiency (EPC) - 70%
Efficiency (NLMPD) ~ >28%
Efficiency (Overall) - 19.6%

The study on the (NLMPPA) (100) shows that compressed output power increases with increase of drain-to-source voltage and gain compression increases with decrease of drain-to-source voltage. It also shows the compressed output power (P2dB) of 12 watt at the input power of 22.3 dBm at the voltage of 9 V. The package (800) analysis of the NLMPPA module shows that the theoretical and Eigen mode resonant frequencies of the bare package have very good agreement with each other and all the resonant modes are appearing outside the frequency range of operation. The only mode which is appearing 200 MHz apart from the left corner frequency of operation is mode2. The field pattern of this mode shows a positive and a negative peak appearing just above the active devices, not on the matching circuits. The resonant mode frequencies of the assembled package are different from the bare one because of the consideration of carrier plates, feed-throughs, isolator, device enclosures and mounting screws. The loaded package analysis shows that below 5 GHz coupling is more compared to bare package, but it can be neglected, since it is out of the required frequency band. The measured test result shows that worst case output gain and power variation over the extreme temperature limits are within ±0.7dB. The C-band NLMPPA fabricated on five layer substrate validates most of the design specifications and also shows very good correlation between studied and measured results.
Package has been analyzed for bare and assembled package to see the cavity effect of the package. The adaptation of pulse concept is to reduce the overall size, weight, and dc power consumption of NLMPPA and thereby reduces the thermal stresses on the RF system as well as satellite power-generating unit. The NLMPPA modules will be used for Radar Imaging Satellite (RISAT) as a part of transmit chain of 288 pairs of TR-Modules, which are going to be placed on the backside of the radiating panel of the active phased array antenna.

WE CLAIM:
1. A non linear microwave pulsed power amplifier for oscillation free pulsed
microwave power output with compressed gain, comprising:
a first input matching network (101) configured for receiving and conditioning a microwave signal;
a first nonlinear power device (102) connected to said first input matching network for amplifying the conditioned microwave signal from said first input matching network;
a first output power matching network (103) connected to said first nonlinear power device for transferring the amplified microwave signal with desired power, from said first nonlinear power device to an isolator (104);
a second input matching network (105) configured for receiving and conditioning output signal from said isolator;
a plurality of second nonlinear power devices (107) connected in parallel to each other, with said splitter (106) for amplifying the microwave signals from the splitter;
a combiner (108) connected to said plurality of second nonlinear power devices for combining the output power of the amplified microwave signals;
a second output power matching network (109) connected to the combiner for yielding optimum output power of the amplified microwave signal; and
an electronic power conditioner (110) configured for supplying power to said first nonlinear power device and said plurality of second nonlinear power devices.
2. The amplifier as claimed in claim 1, wherein said first nonlinear power
device, said splitter, said plurality of second nonlinear power devices and said
combiner are connected in such a way that the power of the amplified microwave
signal from said first nonlinear power device is split into two equal halves by said
splitter and the power of the amplified microwave signals from said plurality of
second nonlinear power devices are combined by the combiner.

3. The amplifier as claimed in claim 1, wherein said isolator absorbs any reflection due to improper matching between the first output power matching network and the second input matching network.
4. The amplifier as claimed in claim 1, wherein said first nonlinear power device and said plurality of second nonlinear power devices are biased by said electronic power conditioner with a drain to source voltage range of 9V±0.2V and a gate to drain voltage range of -1.2V to -1.34V.
5. The amplifier as claimed in claim 1, wherein said first input matching network and said second input matching network are capable of passing a desired microwave input signal through main transmission line by providing low impedance to said desired microwave signal and blocking said desired microwave input signal through parallel line by providing high impedance to said desired microwave signal.
6. The amplifier as claimed in claim 1, wherein said first input matching network and said second input matching network are capable of passing dc signal through parallel line by providing low impedance to said dc signal and blocking said dc signal through main transmission line by providing high impedance to said dc signal.
7. The amplifier as claimed in claim 1, wherein said first nonlinear power device and said plurality of second nonlinear power devices are microwave power amplifiers, which are capable of amplifying microwave signals in the frequency range of 5350 ± 125 MHz.
8. The amplifier as claimed in claim 1, wherein said output matching network is capable of passing a desired microwave output signal through main transmission line by providing low impedance to said desired microwave signal

and blocking said desired microwave output signal through parallel line by providing high impedance to said desired microwave signal.
9. The amplifier as claimed in claim 1, wherein said output matching network is capable of passing dc signal through parallel line by providing low impedance to said dc signal and blocking said dc signal through main transmission line by providing high impedance to said dc signal.
10. The amplifier as claimed in claim 1, wherein the non linear microwave power amplifier assembly is housed in a package (800), which provides a resonant free environment for the microwave signals in the frequency range of 5350 ±125 MHz.
11. The amplifier as claimed in claim 1, wherein the non linear microwave power amplifier is fabricated with metallized substrate (Ti-W-Au-Cu-Ni-Au) with thickness of 0.635 mm, dielectric constant of 9.9, dielectric loss tangent of 0.0007 and metallization thickness of 8-13 pm.
12. The amplifier as claimed in claim 1, wherein the output power of the microwave at the second power devices is 12 watts with a gain of 18.5 dB.
13. A method for amplifying microwave signal to provide oscillation free pulsed microwave power output with compressed gain, comprising the steps of.
conditioning the microwave signal and filtering the dc signal at the input;
biasing a first nonlinear power device and a plurality of second nonlinear power devices with low drain to source voltage;
operating said first nonlinear power device and said plurality of second nonlinear power devices in non linear region;
absorbing any reflection by the isolator due to improper matching between first output power matching network and second input matching network;

splitting and transferring the amplified nnicrowave output power from said first nonlinear power device equally to said plurality of second nonlinear power devices; and
combining the output power from said plurality of second nonlinear power devices and providing a resonance free package to amplify microwave signal.

Documents:

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Patent Number

279509

Indian Patent Application Number

2312/CHE/2009

PG Journal Number

04/2017

Publication Date

27-Jan-2017

Grant Date

24-Jan-2017

Date of Filing

23-Sep-2009

Name of Patentee

INDIAN SPACE RESEARCH ORGANISATION

Applicant Address

ISRO HEADQUARTERS, DEPARTMENT OF SPACE, ANTARIKSH BHAVAN, NEW BEL ROAD, BANGALORE- 560 094

Inventors:

#	Inventor's Name	Inventor's Address
1	RAJ KUMAR ARRORA	SPACE APPLICATIONS CENTER, INDIAN SPACE RESEARCH ORGANISATION (ISRO), AMBAVADI VISTAR PO, JODHPUR TEKRA AHMEDABAD 380 015
2	SURINDER SINGH RANA	SPACE APPLICATIONS CENTER, INDIAN SPACE RESEARCH ORGANISATION (ISRO), AMBAVADI VISTAR PO, JODHPUR TEKRA AHMEDABAD 380 015
3	JOLLY DHAR	SPACE APPLICATIONS CENTER, INDIAN SPACE RESEARCH ORGANISATION (ISRO), AMBAVADI VISTAR PO, JODHPUR TEKRA AHMEDABAD 380 015
4	SAMRITI KUMAR GARG	SPACE APPLICATIONS CENTER, INDIAN SPACE RESEARCH ORGANISATION (ISRO), AMBAVADI VISTAR PO, JODHPUR TEKRA AHMEDABAD 380 015

PCT International Classification Number

H03F 3/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA