DESC:FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

Title: A High Power Compact Solid State Power Amplifier

APPLICANT DETAILS:
(a) NAME: Bharat Electronics Limited
(b) NATIONALITY: Indian
(c) ADDRESS: OUTER RING ROAD, NAGAVARA, BANGALORE 560045,
INDIA

PREAMBLE TO THE DESCRIPTION:
The following specification (particularly) describes the nature of the invention (and the manner in which it is to be performed):
A High Power Compact Solid State Power Amplifier

FIELD OF INVENTION:
The present disclosure/invention relates in general to a power amplifier and more particularly to a high power compact solid state power amplifier with integrated monitoring and reporting system.

BACKGROUND OF THE INVENTION:
The following background discussion includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication expressly or implicitly
In conventional pulsed RADARs, a Power Amplifier (PA) is one of the key sub modules which provides high pulsed power during transmission wherein the RF energy is transmitted to the required distance and returned, and the details of the target can be analyzed based on the returns.
Klystron tubes, magnetron tubes and TWT amplifiers have been used widely for many kinds of radar systems. Microwave tubes have inherent issues such as extremely high voltage requirements, very low duty cycles, long warming time before operation, less usage life and shelf life and periodic maintenance such as degassing. The advantage of tube based amplifiers is that they can generate power of the order of kilowatts but only for a small duty cycle. However, by using the advance signal processing and wave form generation techniques such as pulse compressions, chirp generation, these tubes based amplifiers are being replaced by more reliable SSPA (Solid State Power Amplifiers) which can generate power of few 100s of watts and can be used for a larger duty cycle. The breakthrough of GaN (Gallium Nitride), HEMT (High Electron Mobility Transistor) technology, where the device works from higher DC supply voltages compared to existing Si (Silicon) and GaAs (Gallium Arsenide) technology, enables the amplification and handling of very high RF (Radio Frequency) power using lesser device counts. Thus SSPAs, designed using GaN based devices, can replace the existing microwave tubes in pulsed radars. The high power for the power amplifiers using SSPAs can be achieved by combining multiple higher power devices.
However, there is a limit in combining more devices at higher frequencies such as X-Band, as beyond a certain amount of combining, the efficiency comes down due to the splitting and combining losses and also it becomes a challenge to remove the heat generated and keep the case temperature of the device at its safe level so as to maintain its life time. Hence, it is always beneficial to combine power from devices which generate high power. As the recent requirements of unmanned stations and self-monitored (and reporting) systems are on the rise, an intelligent monitor and control system which monitors all the health status and communicates the same with an operator who is positioned at a far-off distance from the actual radar centre is a crucial part of the Power Amplifier system design.
Hence in the design of power amplifiers, equal emphasis is to be given to both the RF and Control section design. A combination of digital gates and Microcontrollers can be used to perform this function of intelligent monitoring and reporting.
One of the prior art discloses a generation of high power by splitting a medium power signal into a number of low power signals. Then amplifying the signals in each split path, then combining the amplified high-power signal. It also talks about the Fail-soft operation is established by providing switching redundant amplifier. It dwells on the need to stabilize the response by the use of symmetric slope devices.
Another prior art discloses the generation of high power by dividing the low power stage into four paths and each arm is amplified and then recombined to generate the required high power. Forward, reverse powers and currents are monitored, and an Automatic level control protection circuitry based on PIN diode protects the amplifier and maintain a substantial amplifier power output.
Another prior art describes the design of a generic protection circuit for High Power Amplifiers. The health of the Power Amplifier such as voltage, reflected power and temperature are monitored and a feedback-based approach is used as the protection circuit by cutting OFF DC supply of driver stage amplifier based on health status.
Further prior art describes a combined High Power RF/Microwave Amplifier with Multiple Power Amplifier Units and Automatic Power Protection. This prior art describes the design of a High-Power Amplifier designed by dividing the Input signal and amplifying the power in each path and combining the same. This prior art also talks about a control system which communicates with each power amplifier unit through its interface port. This control unit monitors and shuts down the malfunctioning Power amplifier units. It also talks about how power supply is through a common bus and the unit is water cooled.
Further prior art discloses a high Power RF/Microwave Amplifier with Multiple Power Amplifier Units and Automatic Power Protection. This prior art describes the design of a High Power Amplifier designed by dividing the Input signal and amplifying the power in each path and combining the same specifically using radial combiners. The radial combiners’ architecture and mounting is clearly specified. This prior art also talks about a control system which communicates with each power amplifier units through its interface port. This prior art specifically dwells on the automatic replacement of the failed units online without degradation. Finally, it discusses a diode connected power supply architecture for the power supply which ensures there is no loading of the supply.
Further prior art describes the design of a 250W Power Amplifier designed by dividing the Input signal and amplifying the power in each path and combining the same specifically using suspended strip line power combiners and splitters. It addresses the output across frequency and the power output and efficiency attached.
Further prior art describes the design of a 13KW Power Amplifier designed in S-Band by dividing the Input signal and amplifying the power in each path and combining the same specifically using radial combiners and spatial combiners. It illustrates the advantage of radial combining and the graceful degradation in power due to power amplifier failure.
Therefore, there is a need in the art with a high power compact solid state power amplifier with integrated monitoring and reporting system to solve the above-mentioned limitations.

OBJECTIVES OF THE INVENTION:
The primary object of the present invention is to overcome the problem stated in the prior art.
Another object of the present invention provides a high power compact solid state power amplifier with integrated monitoring and reporting system

SUMMARY OF THE INVENTION:
The present invention provides a high power compact solid state power amplifier comprising:
a) an RF isolator (1), where the RF isolator (1) is configured to provide directional signal flow of the signal;
b) a low power splitter section (2) attached to the RF isolator (1), where the low power splitter section (2) is configured to provide a sample out a fraction of the input power to validate the authenticity of the input signal;
c) a schottky diode based RF detector (10a) which detects the pulse modulated RF input signal’s level and converts it into a DC (direct current) voltage;
d) a ADC (Analog to Digital Converter) (11) to whom the DC (Direct Current) voltage is fed as an input is configured to digitizes as input signal;
wherein the digitized value is read by a microcontroller (12) and configured to authenticate the authentic value of the input signal and health of the input signal.
In an embodiment, the splitter module input is fed to a Pre-Driver module (3) which consists of GaAs based MMICs (Monolithic Microwave Integrated Circuits) which are cascaded to amplify the signal input and generate the required RF gain.
In an embodiment, the amplified signal is fed to a driver section/sub module (5), where between the pre-Driver and the Driver section is an interconnecting phase adjustable RF cable (4) is mounted which serves its primary function of transferring the RF power from the pre-driver to the driver section and adjust phase.
In an embodiment, the gysel combiner unit (8) which is a mirror image of the splitter section and contains exactly identical number of paths as the splitter section, where the gysel combiner unit (8) serves as the amalgamation centre where the phase matched high power signal is combined to generate a high power output.
In an embodiment, the output coupler section (9) which aids in taking a very small fraction of the generated power to check the power level and generate the health status of solid state power amplifier.
In an embodiment, the coupled path is fed to a Schottky diode based RF detector (10b) , which converts the high frequency RF signal to a DC voltage and sends it to the ADC which digitizes the same and presents it to the controller, which in the presence of the cover pulse generates a forward power health signal.
In an embodiment, the amplifier is the RF circulator (16) which provides directionality to the amplifier, whereby the output is coupled to the antenna and any reflections from the output is passed on to the third port of the circulator which consists of a reverse coupler (14).
In an embodiment, the transmit coupler section there is as RF detector (10c) which converts the RF signal to DC signal corresponding to the reflected signal.
The present invention provides a method of designing a high power compact solid state power amplifier with an Integrated Monitoring and a Reporting System comprising of a plurality of Gysel architecture-based splitting / combining, with compact Flat capacitors as charge storage elements, remote reporting and remote programming unit embedded in it.

DETAILED DESCRIPTION OF DRAWINGS:
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of their scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings in which:
Fig. 1: illustrates a block diagram of a high power X-band solid state power amplifier.
Fig. 2: illustrates a circuit architecture of switching logic and high power switching FET (Field Effect Transistor).
Fig. 3: illustrates a communication diagram of high-power X-band solid state power amplifier and remote terminal.

DETAILED DESCRIPTION:
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
The terms “comprises”, “comprising”, “includes”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a system or apparatus proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or method.
The present invention relates to a High Power Compact Solid State Power Amplifier with Integrated Monitoring and Reporting System. The present invention also describes a method of design of a forced air-cooled high power GaN based solid state amplifier with a unique amalgamation of combinational and microcontroller-based monitor and control circuit.
The present invention features a unique Multivibrator based pulse width protection circuit which ensures proper operation and prevents it to go in continuous mode of operation. The developed control circuit features a remotely programmable microcontroller in which the threshold limits and tables can be altered dynamically and the same which remotely communicates with an external system. The structure is so designed that it can be upscaled from one to two to three to four power devices with minor tweaking of the two related PCBs. The splitting and combining consists of a plurality of Gysel based power splitters and a plurality of Gysel based power combiners. The present invention incorporates a high flat pack, Ultra Long Life, Aluminum Electrolytic capacitor which can be located at a depth in the structure and need not be mounted on the PCB. Also, the structure is so designed that the feed for the voltages of the power devices is done from underneath using a unique arrangement which avoids crossover the power traces. The present invention discloses a unique method of phase matching between two similar amplifiers by phase adjusting the interconnecting phase adjustable cables and further, there is a method to check the authenticity of the input signal.
In one embodiment, the present invention discloses a forced air cooled system with integrated heatsink to cater for the cooling of the Power Amplifier.
In one embodiment, the present invention employs a Flat pack, Ultra Long Life, Aluminum Electrolytic capacitor as a charge storage capacitor which is mounted on the housing.
In one embodiment, the present invention specifically employs a multi vibrator based protection circuits which ensures proper operation and prevents it to go in continuous mode of operation.
In one embodiment, the present invention uses a planar gysel based splitter and combiners for combining the power.
In one embodiment, the structure of the present invention is so optimized that even and odd combing in the same physical dimensions is possible by replacing only 2 PCBs.
In one embodiment, the present invention is different in a way that it can be remotely monitored through LAN and can be programmed remotely without physical human intervention requirement.
In one embodiment, the present invention provides a method of designing a High Power Compact Solid State Power Amplifier with Integrated Monitoring and Reporting System comprising of a plurality of Gysel architecture based splitting/combining, with compact Flat capacitors as charge storage elements, remote reporting and remote programming features embedded in it.
In one embodiment, the present invention discloses a forced air cooled High Power X-Band Solid State Compact Power Amplifier with controller based integrated Monitoring and Reporting System.
In one embodiment, the present invention method comprises splitting of the high power amplifiers at the input stage using planar high power handling gysel power splitters and recombining using high power handling gysel power combiners.
In one embodiment, the present invention uses cost effective microcontroller and ADC (Analog to Digital Converter) based circuits for monitoring and reporting the status of the power amplifiers.
In one embodiment, the present invention employs multi vibrator based triggering and protection circuits which limits the maximum pulse width of the signal and prevents it from going into Continuous operation mode.
In one embodiment of the present invention, as multiple power amplifiers are combined at the system level, the present invention has a provision of phase matching using a unique RF length adjustment.
In one embodiment, the use of detection circuits at the input clearly indicates the health of the input power.
In one embodiment, the present invention adopts a unique power supply distribution method where the supply to the device is fed from the bottom and there is no cross over the RF trace.
In one embodiment, a novel method of using high voltage pulsing circuits and a sensitive digital monitoring circuit is implemented in a common PCB by using unique PCB design techniques.
In one embodiment, the physical architecture is planned such a maximum of 4 devices can be combined and can be downgraded to 3, 2 and a single device by changing only 2 PCBs.
In one embodiment, the monitoring and reporting of the amplifier is so designed that it can be remotely programmed and remotely monitored without human intervention.
Reference Numerals:
1 --- RF Isolator
2--- Low power Splitter
3 --- Pre Driver Sub module
4 --- Phase adjustable Cable
5 --- Driver Sub Module
6 --- 1 to N Splitter stage
7a ,7b ,7c ,7d --- High Power GaN based Amplifier
8 --- N to 1 Power Combiner
9 --- Coupler for forward power detection
10a,10b,10c --- Schottky Diode based RF Detectors
11 --- Multichannel ADC
12 --- Microcontroller
13a,13b --- 50 ohm (?) low power termination
14 --- Coupler for reverse power detection
15 --- 50 ohm (?) high power termination
16 --- RF Circulator
17 --- Health Check Combinational Logic Circuit
18 --- Gate Control generation Combinational Logic Circuit
19 --- High Power FET
20 --- Capacitor Bank
21--- LAN Interface
22--- Programming Interface
23--- Remote Terminal
24--- High Power X-Band Solid State Power Amplifier
Figure 1 shows a block diagram of a high power X-band solid state power amplifier according to an exemplary implementation of the present disclosure/ invention.
The figure depicts the block diagram of High Power X-Band Solid State Power Amplifier. The Solid State Power Amplifier takes an input RF Input signal which is a very low power high frequency signal. At the input of the amplifier there is an RF Isolator (1) for directional signal flow of the signal and provide a perfect match to the input section and provide a good return loss to the external system. Following the input isolator is a low power splitter section (2). The low power splitter section (2) is to sample out a fraction of the input power to validate the authenticity of the input signal. On the sampled path of the splitter there is a Schottky diode based RF detector (10a) which detects the pulse modulated RF input signal’s level and converts it into a DC (Direct Current) voltage, which if fed as an input to the ADC (Analog to Digital Converter) (11) which digitizes this input signal. The digitized value is read by the microcontroller (12) and the authentic value of the input signal can be determined and health of the input signal can be determined. The main split path of the splitter module is fed to Pre-Driver module (3) which consists of GaAs based MMICs (Monolithic Microwave Integrated Circuits) which are cascaded to amplify the input signal and generate the required RF gain. The amplified signal is then fed to a Driver section/sub module (5). Between the Pre-Driver and the Driver section is an interconnecting RF cable section/phase adjustable cable (4) which serves its primary function of transferring the RF power from the pre-driver to the driver section. It also has been utilized to serve as a unique function of phase matching between two different inventions (amplifiers) which can be phase shifted due to a variety of reasons. The initial phase difference between the two inventions (amplifiers) is measured and the cable is phase trimmed to match two amplifiers. The amplifier comprises 1 to N gysel based high power splitter (6), the value of N can range from 2 to 4. Indicating there can be two, three or four splits of the input signal. Following this is the actual GaN based power amplifier device (7a, 7b, 7c, 7d) which generates the required high power. The amplifier device is based on the number of splits from the previous section, the count of the devices can be varied from two, three to four. Following this high power stage is the high power N is to 1 Gysel combiner (8) which is a mirror image of the splitter section and contains exactly identical number of paths as the splitter section. This section serves as the amalgamation centre where the phase matched high power signal is combined to generate a high power output. Following the combiner is the output coupler section (9) which aids in taking a very small fraction of the generated power to check the power level and generate the health status. The coupled path is fed to a Schottky diode based RF detector (10b) , which converts the high frequency RF signal to a DC voltage and sends it to the ADC which digitizes the same and presents it to the controller, which in the presence of the cover pulse generates a forward power health signal. The isolated port of this coupler is terminated using 50? termination (13 a).
The final section in the amplifier is the RF circulator (16) which provides directionality to the amplifier, whereby the output is coupled to the antenna and any reflections from the output is passed on to the third port of the circulator which consists of a reverse coupler (14). Similar to the transmit coupler section there is as RF detector (10c) which converts the RF signal to DC signal corresponding to the reflected signal. This again is digitized by the ADC and presented to the Microcontroller. Based on the level of the reflected signal the microcontroller generates the VSWR health. The reflected power is terminated using a high power termination (15).
Figure 2 shows a circuit architecture of switching logic and high power switching FET (Field Effect Transistor) according to an exemplary implementation of the present disclosure/ invention.
The figure depicts Switching Logic and high Power switching FET circuit architecture. The present invention amplifier is a highly delicate combination of a combinational logic circuits and controller based detection circuits. Only if the health of all these parameters are within the required limits, the power device of the amplifier is turned ON. The combinational logic health check circuit (17) combines all the health’s and generates a combined health status to another section. The health’s are primarily voltage health, Sequence health, Current health, Temperature health and a unique Multivibrator based pulse width limiting circuit which prevents the amplifier from going into continuous mode of operation and limits the operational pulse width. In addition, digitized health status from the ADC namely, forward power health, reverse power health and Input power health are monitored in the Microcontroller and based on these health statuses the controller generates a universal control to a combinational logic block (18). The circuit (18) then analyses the two controls generated in the previous stages and decides to switch on the high power FET (19). This FET basically acts as a switch which connects a capacitor bank (20) which comprises of Flat pack, Ultra Long Life, Aluminum Electrolytic capacitor which is positioned at the rear unutilized section and is clamped to the mechanical structure.
Figure 3 shows a communication diagram of high power X-band solid state power amplifier and remote terminal according to an exemplary implementation of the present disclosure/ invention.
The figure depicts the High Power X-Band Solid State Power Amplifier (24) and Remote terminal (23) Communication Diagram. As explained in the previous section, the amplifier consists of a microcontroller in which a global control signal is generated to turn ON the high power FETs, the threshold of the status can be adaptively changed online using the programming Interface (22). This ensures that the amplifier can be operated dynamically as per the requirement. All the health status can be monitored on the LAN interface (21) by a remote observer or remote terminal which can be stationed at a distance from the actual site, thereby allowing proper unmanned operation of the amplifier.
In one embodiment, the present invention provides a novel method of designing a High Power Compact Solid State Power Amplifier with Integrated Monitoring and Reporting System comprising of a plurality of Gysel architecture based splitting / combining, with compact Flat capacitors as charge storage elements, remote reporting and remote programming features embedded in it.
In one embodiment of the present invention, a novel technique of integrating a flat pack, Aluminum electrolytic capacitor as a charge storage capacitor mounted on the housing and thereby leading to a compact structure.
In one embodiment, the present invention provides a novel method of using a Retriggerable Monostable Multivibrator based circuitry to prevent continuous mode of operation of the invention and protect it from damage.
In one embodiment, the present invention provides a unique combination method consisting of a digital logic and microcontroller based circuit to monitor and control the operation of the invention and protect the invention from damage.
In one embodiment, the present invention provides a novel method to remotely program the microcontroller based circuit and increase the threshold limits towards the margin of the amplifier when required and a method to update the status of the amplifier to the remote user through LAN using a microcontroller based circuit.
In one embodiment, the present invention provides a unique method to integrate a high voltage, high current pulsing circuit and a sensitive analog sub-volt circuit on a same PCB using differentiated ground to increase the compactness of the amplifier.
The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the substance of the invention may occur to person skilled in the art, the invention should be construed to include everything within the scope of the invention.
,CLAIMS:We Claim:
1. A novel method of designing a High Power Compact Solid State Power Amplifier with Integrated Monitoring and Reporting System comprising of a plurality of Gysel architecture based splitting / combining, with compact Flat capacitors as charge storage elements, remote reporting and remote programming features embedded in it.
2. As per claim 1, a novel technique of integrating a flat pack, Aluminum electrolytic capacitor as a charge storage capacitor mounted on the housing and thereby leading to a compact structure.
3. As per claim 1, a novel method of using a Retriggerable Monostable Multivibrator based circuitry to prevent continuous mode of operation of the invention and protect it from damage.
4. As per claim 1, a unique combination method consisting of a digital logic and microcontroller based circuit to monitor and control the operation of the invention and protect the invention from damage.
5. As per claim 1, a novel method to remotely program the microcontroller based circuit and increase the threshold limits towards the margin of the invention when required and a method to update the status of the invention to the remote user through LAN using a microcontroller based circuit.
6. As per claim 1, a unique method to integrate a high voltage, high current pulsing circuit and a sensitive analog sub-volt circuit on a same PCB using differentiated ground to increase the compactness of the invention.