Ka-band 20W solid-state power amplifier and production process thereof

Abstract

The invention discloses a Ka-band 20W solid-state power amplifier and a production process thereof. The solid-state power amplifier comprises a Ka pre-stage circuit module, a Ka 20W final-stage circuit module and a Ka power supply module, the Ka pre-stage circuit module comprises an input power detector, a temperature compensation attenuator and an amplifier, and the output power of the Ka pre-stage circuit module is greater than 5W; the Ka20W final-stage circuit module is used for carrying out space power synthesis by four 8-watt gallium nitride chips; the Ka power supply module provides power supply voltage for the Ka preceding-stage circuit module and the Ka 20W final-stage circuit module. By adopting the technical scheme, the microwave index of the module is excellent; an E-T space power synthesis technology is adopted, so that the method has the characteristics of high synthesis efficiency and the like; a phase matching technology is carried out by adopting a gallium nitride active single-card microwave index test, so that the synthesis efficiency is improved; a preferable process scheme is adopted, so that products meeting performance indexes are beneficial to batch production; the antenna has excellent performance of high gain, high power, stability and reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of millimeter wave power amplifiers. More specifically, the present invention relates to a Ka-band 20W solid-state power amplifier, which can be used in the transmission channel of satellite communication and the Ka-band millimeter wave radar and other fields. The present invention also relates to the production process of the power amplifier. Background Art

[0002] Millimeter wave power amplifiers are important devices in satellite communication systems, multimedia wireless systems, high-speed WLANs, and high-speed wireless personal area networks (WPANs). Due to the high cost of millimeter wave devices, they were previously mainly used in the military. However, with the rapid development of high-speed broadband wireless communications, automotive assisted driving, security inspections, medical testing and other application fields, millimeter waves have also been widely studied and applied in the civilian field in recent years.

[0003] Traditional millimeter-wave monolithic integrated circuits mainly use compound semiconductor processes, such as gallium arsenide (GaAs) and indium phosphide (InP); they have good performance in the millimeter-wave frequency band and are the mainstream integrated circuit process in this frequency band. On the other hand, silicon-based (CMOS, SiGe, etc.) millimeter-wave and sub-millimeter-wave integrated circuits have also made great progress in the past decade.

[0004] Millimeter wave power amplifiers also have many practical applications in low-orbit satellite communications, such as Musk's Starlink system. In low-orbit high-throughput, the capacity of a single satellite can reach tens of Gbps to hundreds of Gbps, greatly increasing capacity and reducing unit bandwidth costs, opening a new era of satellite communications.

[0005] Data from low-orbit high-throughput satellites needs to pass through gateway stations, which are equivalent to large base stations serving satellites. Due to the large communication capacity, new gateway stations with high frequency and large bandwidth are required to work in the Ka band, with high power. The average power is generally above 20W. This power level is the most advanced in the millimeter wave field worldwide, and only a few manufacturers in the world can produce it.

[0006] With the increase in satellite communication and radar business volume, the original S, C, X, Ku and other frequency band resources are close to saturation and cannot meet the increased business day and night.

[0007] Ka-band amplifiers can also meet the demand and have the characteristics of small size. The original S, C, X, Ku and other frequency bands generally use microstrip circuits for power synthesis. This power synthesis is synthesized in multiple stages and has low synthesis efficiency. The Ka-band amplifier uses spatial power synthesis technology and has the characteristics of high synthesis efficiency.

[0008] Traditional low-frequency amplifiers generally use chips based on potassium arsenide technology. This type of chip not only has low output power, but also has low efficiency, high heat dissipation, and is easy to burn out.

[0009] The keywords "Ka; band; solid-state; power; amplifier" were used to search the existing published technical literature, and the following search results related to the present application were obtained:

[0010] 1. Chinese patent document: "A Ka-band solid-state power amplifier link", patent (application) number: 201721305217.9; the technical solution recorded is:

[0011] “Ka-band solid-state power amplifier link, comprising: a first-stage power division module, a second-stage power division module, a first-stage combining module, a second-stage combining module and a third-stage combining module; the first-stage power division module is provided with three output ends, each output end is connected to the input end of a waveguide bridge power divider of the second-stage power division module; each waveguide bridge power divider in the second-stage power division module is provided with two output ends, each output end is connected to the input end of a power amplifier module of the first-stage combining module; each waveguide bridge combiner in the second-stage combining module is provided with two input ends, each input end is connected to the output end of a power amplifier module of the first-stage combining module; the third-stage combining module is provided with three input ends, each input end is connected to the output end of a waveguide bridge combiner of the second-stage combining module”;

[0012] The technical effects recorded are:

[0013] "It realizes the combining method of non-even-numbered paths, which has the advantages of small insertion loss, high combining efficiency, good standing wave and high isolation."

[0014] 2. Chinese patent document: "KA-band high-power amplifier and implementation method thereof", patent (application) number: 202010162014.9; the technical solution recorded therein is:

[0015] “The KA-band high-power amplifier comprises: a frequency conversion unit, a power amplifier unit, a power supply unit, and a monitoring unit; wherein the frequency conversion unit is connected to a crystal oscillator for generating a 10 MHz reference signal through a first filter; and the monitoring unit is provided with a 10 / 100M Ethernet interface for communication with an external device”;

[0016] The technical effects recorded are:

[0017] "The intermediate frequency signal can be converted by setting a frequency conversion unit to adapt it to signal communication in the KA frequency (wave) band. At the same time, by adding an Ethernet communication interface to the amplifier, the amplifier can directly communicate data with the outside world, which is convenient for monitoring its working status and adjusting its parameters. Furthermore, by setting a reference signal source on the amplifier, it can be independently in a working state without the intervention of external equipment, with better adaptability, and stronger stability and controllability of the equipment operation."

[0018] However, the technical solutions recorded in the above-mentioned technical documents and the related technical solutions currently in public application have not been able to solve the problems and defects existing in the prior art of "low output power, low efficiency, large heat dissipation, and easy burning". Summary of the invention

[0019] The present invention provides a Ka-band 20W solid-state power amplifier, the purpose of which is to solve the difficult problem of requiring high power, long life, high efficiency and high linearity for millimeter waves.

[0020] In order to achieve the above object, the technical solution adopted by the present invention is:

[0021] The Ka-band 20W solid-state power amplifier of the present invention comprises a Ka front-stage circuit module, a Ka20W final-stage circuit module and a Ka power supply module; the Ka front-stage circuit module comprises an input power detector, a temperature-compensated attenuator and an amplifier, and its output power is greater than 5W; the Ka20W final-stage circuit module performs spatial power synthesis by four 8-watt gallium nitride (GaN) chips; the Ka power supply module provides power supply voltage for the Ka front-stage circuit module and the Ka20W final-stage circuit module.

[0022] In the Ka front-stage circuit module, the millimeter wave signal 29.4GHz~31GHz, the power is -5dBm, enters the Ka-band power divider after passing through the RF connector, and then becomes two signals, and the power of the two equal-amplitude signals is -8.5dBm.

[0023] The first signal of the two signals enters the input power detector for input detection processing to detect the input model size, and the detected analog signal is sent to the external host computer module for processing, thereby determining the input power size of the input signal.

[0024] The second signal of the two signals enters the RF branch, and the signal enters the first-stage temperature-compensated attenuator; then, the signal continues to enter the first-stage equalizer; the signal enters the first-stage amplifier again; the signal enters the second-stage equalizer again; the signal enters the second-stage temperature-compensated attenuator; and the signal finally enters the driver amplifier.

[0025] In the Ka20W final stage circuit module, ET's waveguide synthesizer is used to perform spatial power synthesis.

[0026] The signal output from the Ka front-stage circuit module is 29.4GHz~31GHz, with an output power of 26.5dBm; it enters the Ka20W final-stage circuit module; at 27.5~31GHz, it provides a small signal gain of 30dB, a power gain of 17dB, a typical output power greater than 39dBm, and a third-order intermodulation of 33dBm at dual-tone output, less than 30dBc, the power supply gate voltage is adjustable at -2.5V, and the drain voltage is 20V.

[0027] The GaN single card phase matching adopts an independent test fixture to perform manual phase testing before synthesis. After each GaN active single card module is fixed to the test fixture by screws, power is applied to test the indicators, first adding a gate voltage of about -2.5V, and then adding a drain voltage of +20V. The gate voltage can be adjusted appropriately. Therefore, the microwave indicators of the GaN active single card module will also change, and the corresponding active single card static current will also change. The static current change range is between 280mA and 580mA, and the test is performed. The test process is as follows:

[0028] Before power-on testing, attach a layer of thermal pad to the heat dissipation surface of the card to ensure good heat dissipation of the card;

[0029] Place the single card on the heat sink, install microstrip to coaxial connectors at the input and output ends, connect the input end to the vector network input end, and connect the output end to the vector network output end with a 30dB attenuator.

[0030] Single card power-on: first add gate voltage -3V to the power supply end, then add drain voltage +202V to the power supply end; at this time, the leakage current is very small, 0.05A; turn on the vector network input signal;

[0031] Test gain parameters: fine-tune the gate voltage from -3V after power-on; fine-tune the gate voltage until the vector network displays 29.4GHz and the gain is 29db, record the gain and phase of 29.4Ghz, 30.2Ghz, and 31Ghz, and record the corresponding gate voltage value and static current;

[0032] The power meter tests the output power of a single card: select the grid voltage when the gain of the single card is 29dB, at this time, the DC regulated power supply +20V current limit 1A, the signal source and the driving amplifier push the single card power, the driving amplifier is powered on in sequence -5V, current limit 0.1A; +6.3V, current limit 2A, +10V, current limit 2.5A; turn on the signal source signal switch -30dBm, at the beginning of power on, the current limit is 1A; when the power is pushed to 30dBm, the current is limited to 5A, and the single card output power at 29.4Ghz, 30.2Ghz, and 31Ghz is recorded. The output power of the single card is ≥39dBm;

[0033] When measuring power, if the power value displayed by the output power meter increases by less than 0.3dB when the input signal source increases by 1dB, the power cannot be pushed;

[0034] Turn off +10V, +6.3V, +20V, -5V and single card grid voltage in sequence, making sure to turn off the positive power first and then the negative power;

[0035] Record the test data in a table and use a marker to record the test index phase on the bottom of the single card;

[0036] After the test is passed, the single card is placed upside down in an anti-static box and transferred to the next process.

[0037] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a production process of the above-mentioned Ka-band 20W solid-state power amplifier, and its technical solution is:

[0038] The production process mainly includes the following steps: circuit board sintering, component sintering, electrical assembly welding, vapor phase cleaning, eutectic, gluing, gold wire bonding, submodule adjustment and testing, whole machine assembly, whole machine adjustment and testing, and environmental testing.

[0039] In the gold wire bonding process, the chip device is sintered to the metal shielding box, the gold wire bonding process is used to achieve electrical interconnection, and the corresponding points on the dielectric circuit board are connected to the corresponding wiring points of the bare chip, so that the module has the function of a circuit.

[0040] The gold wire bonding process requirements are as follows:

[0041] 1. Before formal production, use a dynamometer to measure the bonding pressure three times, requiring the pressure to be between 30 and 40g, and then bond 10 gold wires on the same substrate to test their bonding strength. The minimum bonding strength is required to be 3.5g, and the average bonding strength is not less than 5g;

[0042] 2. Bonding order: Chip first, that is, the first bonding point is on the chip, usually divided into GaAs chip to chip capacitor, GaAs chip to Rogers, GaAs chip to GaAs chip, chip capacitor to chip capacitor;

[0043] 3. 25.4μm gold wire bonding heating stage temperature: 100℃±5℃, wedge force is 18~24gf, wire bonding.

[0044] The present invention adopts the above technical scheme, and its module has excellent microwave indicators, an operating frequency of 29.4GHz to 31GHz, an output power greater than 30W, a gain greater than 45dB, and a third-order intermodulation (two-tone output is tested 3dB lower than the rated power) less than -25dBc; the high and low temperature gain variation is less than 3dB (working environment temperature -40°C to +55°C), and the in-band gain flatness is less than 2dB; the module adopts ET spatial power synthesis technology, and has the characteristics of high synthesis efficiency; gallium nitride (GaN) active single card microwave index test is used for phase matching technology to improve synthesis efficiency; the preferred process scheme is adopted to achieve products that meet performance indicators and are conducive to mass production; therefore, the Ka-band 20W solid-state power amplifier of the present invention has excellent performances of high gain, high power, stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The contents shown in the attached drawings (and the marks in the drawings) are briefly described as follows:

[0046] Figure 1 This is the HFSS model diagram of waveguide to microstrip;

[0047] Figure 2 This is the waveguide to microstrip assembly diagram;

[0048] Figure 3 This is the 3D model diagram of the ET surface waveguide power divider / synthesizer;

[0049] Figure 4 Assembly diagram for ET's waveguide synthesizer;

[0050] Figure 5 This is the structure diagram of the active single-card fixture assembly;

[0051] Figure 5 The markings are: 1, box body 1, 2, box body 2, 3, cover plate;

[0052] Figure 5-1 for Figure 5 a top view of the structure shown;

[0053] Figure 5-2 for Figure 5-1 AA section view in;

[0054] Figure 5-3 for Figure 5 a bottom view of the structure shown;

[0055] Figure 5-4 for Figure 5 a rear view of the structure shown;

[0056] Figure 5-5 for Figure 5 A view of the mating surface of the active single card fixture assembly shown;

[0057] Figure 5-6 for Figure 5-5 B is a partial enlarged view;

[0058] Figure 6-1 This is the active single card phase gain test block diagram;

[0059] Figure 6-2 This is the block diagram of the active single card output power test;

[0060] Figure 7 It is a process flow chart of Ka20WPAM type Ka-band 20W power amplifier-control module and Ka20WPAM type Ka-band 20W power amplifier-feed module;

[0061] Figure 8 The process flow chart of Ka20W drive and amplifier microwave circuit module and Ka20W power amplifier microwave circuit module;

[0062] Fig. 9 This is the process flow chart of the Ka20W power amplifier module;

[0063] Fig.10 This is the module principle block diagram of the solid-state power amplifier;

[0064] Fig.11 This is the principle block diagram of the pre-stage circuit of the Ka solid-state power amplifier;

[0065] exist Fig.11 In the figure, U1 and U6 are amplifiers WFD290320-P37; U2, U3, and U6 are temperature-compensated attenuators NC13152C-140; U4 and U7 are equalizers WSDG290310-2; and U8 is a power divider VD7741.

[0066] Fig.12 This is the assembly diagram of the pre-stage circuit of the Ka solid-state power amplifier;

[0067] Figure 12-1 to Figure 12-7 They are Fig.12 A to G are partial enlarged views;

[0068] Fig.13 This is the assembly diagram of the Ka final stage 20W circuit module;

[0069] Figure 13-1 yes Fig.13 A magnified view of the part H in FIG. DETAILED DESCRIPTION

[0070] The specific implementation modes of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0071] like Figure 1-Figure 13 As shown, the Ka-band 20W solid-state power amplifier of the present invention is a power amplifier with high gain, high power, stable and reliable performance.

[0072] In order to solve the problems existing in the prior art and overcome its defects, and to achieve the invention purpose of solving the difficult problem of requiring high power, long life, high efficiency and high linearity for millimeter waves, the technical solution adopted by the present invention is:

[0073] like Fig.10 As shown in the module principle block diagram, the Ka-band 20W solid-state power amplifier of the present invention includes a Ka front-stage circuit module, a Ka20W final-stage circuit module and a Ka power supply module; the Ka front-stage circuit module includes an input power detector, a temperature-compensated attenuator, and an amplifier, and its output power is greater than 5W; the Ka20W final-stage circuit module performs spatial power synthesis by four 8-watt gallium nitride (GaN) chips; the Ka power supply module provides power supply voltage for the Ka front-stage circuit module and the Ka20W final-stage circuit module.

[0074] The invention discloses a power amplifier designed based on a gallium nitride (GaN) chip, and has the characteristics of large output power, large gain, good third-order intermodulation, high efficiency and the like.

[0075] The microwave index of the power amplifier module is excellent; the gain variation at high and low temperatures is small; the module adopts ET space power synthesis technology and has the characteristics of high synthesis efficiency; the high-power high-frequency devices based on gallium nitride (GaN) technology are extended to the millimeter wave frequency band, and the gallium nitride (GaN) active single-card microwave index test is used for phase matching technology to improve the synthesis efficiency; therefore, the Ka-band 20W solid-state power amplifier of the present invention has excellent performances of high gain, high power, stability and reliability.

[0076] Specifically:

[0077] 1. Ka pre-stage circuit module:

[0078] The Ka pre-stage circuit module includes input power detection, gain temperature compensation, gain amplification, output power greater than 5W and other functions; its principle reference Fig.11 The principle block diagram of the Ka solid-state power amplifier pre-stage circuit of the present invention is shown as follows:

[0079] The Ka front-stage circuit module has a millimeter wave signal of 29.4GHz to 31GHz and a power of -5dBm. It passes through the RF connector (D360S15F05) and then enters the Ka-band power divider U8 (VD7741), and then becomes two signals, and the power of the two equal-amplitude signals is -8.5dBm.

[0080] Transmission paths of two signals:

[0081] 1. The first signal of the two signals enters the input power detector U9 (NC19803C-1240), refer to Fig.12 Assembly diagram of the pre-stage circuit of the Ka solid-state power amplifier of the present invention. Fig.12 Also includes Figure 12-1 to Figure 12-7 , respectively Fig.12 A~G are enlarged views of the parts.

[0082] Ka pre-stage circuit assembly diagram From the enlarged views F and G, it can be seen that the power divider U8 (VD7741) is eutectic on carrier Z7 carrier-(1.44×1.8×0.2)mm through eutectic solder, and the power detector U9 (NC19803C-1240) and C34, C35, C36 chip capacitors JCS11B-15-UX-50V-101M are eutectic on carrier Z8 carrier-(2.1×2.3×0.2)mm.

[0083] This path enters the input power detector for input detection processing to detect the input model size. The detected analog signal is sent to the external host computer module for processing, thereby determining the input signal input power size.

[0084] 2. The second signal of the two signals enters the RF branch:

[0085] (1) The signal enters the first-stage temperature-compensated attenuator U6 NC13152C-140:

[0086] The first stage temperature compensation attenuator and C33 chip capacitor JCS11B-15-UX-50V-101M eutectic Z6 carrier (1.21×2.3×0.2) mm, temperature compensation attenuator NC13152C-140 power supply -5V, providing 3dB temperature compensation at -40℃~+55℃ and frequency at DC~40GHz;

[0087] Since the amplifier gain increases at low temperatures and decreases at high temperatures, a temperature compensation attenuator is needed. Its function is opposite to the amplifier characteristics and can compensate for the high and low temperature gain characteristics of the amplifier. The temperature compensation attenuator NC13152C-140 provides 3dB temperature compensation in the entire operating temperature range.

[0088] The addition of a temperature-compensated attenuator not only improves the stability of the amplifier module, but also ensures the high and low temperature gain variation of the entire module. At room temperature, the insertion loss of the temperature-compensated attenuator NC13152C-140 at 30GHz is 3dB, which means that the power of the signal becomes -11.5dBm after passing through the temperature-compensated attenuator.

[0089] (2) The signal continues to enter the first-stage equalizer U7 WSDG290310-2:

[0090] The equalizer WSDG290310-2 eutectic is on a Z3 carrier - (0.81×2.5×0.2) mm. The first-stage equalizer WSDG290310-2 provides 2dB of equalization at 29 to 31GHz and 2dB of insertion loss at 30GHz. Since the entire module uses a passive power divider and three temperature-compensated attenuators, as well as two amplifiers, the gain characteristics of these devices are: operating frequency 29.4GHz to 31GHz;

[0091] As the frequency increases, the gain decreases or the insertion loss increases, an equalizer with opposite characteristics is needed for equalization. After the equalizer, the power becomes -13.5dBm.

[0092] (3) The signal enters the first-stage amplifier NC11307C-2931 again;

[0093] The first-stage amplifier NC11307C-2931 and C30, C31, C32 chip capacitors JCS11B-15-UX-50V-101M eutectic on carrier Z4 carrier-(2.11×2.7×0.2)mm, the first-stage amplifier NC11307C-2931 power supply gate voltage Vg-0.7V, and the drain voltage Vd+5V current 110mA, operating frequency 29.4GHz~31.5GHz, small signal gain 27dB, saturated output power 25dBm;

[0094] (4) After the first-stage amplifier, the power becomes 13.5dBm, and the signal enters the second-stage equalizer U4WSDG290310-2 again. The equalizer WSDG290310-2 eutectic is on the Z3 carrier - (0.81×2.5×0.2)mm. The second-stage equalizer WSDG290310-2 provides 2dB of equalization at 29-31GHz and 2dB of insertion loss at 30GHz. After the second-stage equalizer, the power becomes 11.5dBm;

[0095] (5) The signal enters the second-stage temperature-compensated attenuator NC13152C-140;

[0096] The second-stage temperature-compensated attenuator is composed of two temperature-compensated attenuators U2 and U3 NC13152C-140 and C28 and C29 chip capacitors JCS11B-15-UX-50V-101M eutectic Z2 carrier - (1.21×2.3×0.2) mm. One temperature-compensated attenuator NC13152C-140 is powered by -5V, providing 3dB temperature compensation at -40℃~+55℃ and frequency at DC~40GHz. The two temperature-compensated attenuators add up to 6dB temperature compensation. At room temperature, the insertion loss of the two temperature-compensated attenuators NC13152C-140 at 30GHz is 6dB. After the second-stage temperature-compensated attenuator, the power becomes 5.5dBm.

[0097] (6) The signal finally enters the driver amplifier U1 WFD290320-P37;

[0098] The driver amplifier U1 WFD290320-P37 and C20, C21, C22, C23, C24, C25, C26, C27 chip capacitors JCS11B-15-UX-50V-101M, and C14, C15, C16, C17, C18, C19 chip capacitors JCS11B-30-UX-50V-102M eutectic are on Z1 carrier molybdenum copper carrier Mo80Cu20-14mm×3.54mm×0.2mm. The driver amplifier U1WFD290320-P37 operates at a frequency of 29GHz~32GHz, with a small signal gain greater than 21dB, a power gain of 15dB, an output power greater than 37dBm, a power supply gate voltage Vg-0.6V, and a drain voltage Vd+6V current of 3400mA. The input power of the input signal changes from 5.5dBm to 26.5dBm.

[0099] 2. Ka20W final stage circuit module:

[0100] 1. About waveguide-microstrip conversion circuit:

[0101] This signal enters the final amplifier network, and the output of the driver amplifier is in waveguide form BJ320. The output makes a transition from microstrip to waveguide in order to connect the final four-way waveguide spatial synthesis input; secondly, the maximum output is close to 37dBm, and the loss of ordinary microstrip is too large.

[0102] (1) Waveguide-microstrip conversion circuits are divided into the following categories: ridge waveguide conversion type, transition fin line conversion type, and probe conversion type:

[0103] 1) Although the ridge waveguide conversion type is simple in principle, it requires precise machining;

[0104] 2) The transition fin line conversion design is difficult and has high loss;

[0105] 3) Compared with the above two circuits, the probe conversion type has obvious advantages: low insertion loss, small voltage standing wave ratio, large working bandwidth, and easy processing and debugging.

[0106] (2) The probe type waveguide-microstrip conversion circuit can be divided into coaxial probe type and microstrip probe type based on the structure and manufacturing form:

[0107] 1) Coaxial probe type waveguide microstrip conversion circuit:

[0108] The coaxial probe waveguide-microstrip conversion circuit is easy to design and is a relatively mature circuit form, but it also has the following disadvantages:

[0109] (a) The structure size is large;

[0110] (b) Higher cost;

[0111] (c) The process is relatively complex to implement.

[0112] Usually in solid-state circuits with lower frequencies (below the Ka band), coaxial probe type waveguide-microstrip conversion circuits are widely used. However, high-performance coaxial probes in the Ka band are not easy to make and are costly. In addition, since the geometric structure of millimeter-wave circuits is very small, the errors caused by the complex assembly process of coaxial probes may lead to deterioration of circuit performance.

[0113] In the existing waveguide-microstrip conversion circuit design method, the factor of microwave signal radiation in non-main mode in the rectangular waveguide cavity is not comprehensively considered, which will lead to deviations in the design results, so that the process of actual microstrip line circuit manufacturing cannot be accurately guided, resulting in generally unsatisfactory insertion loss.

[0114] 2) Microstrip probe waveguide microstrip conversion circuit:

[0115] The Ka-band microstrip probe type waveguide-microstrip conversion circuit comprises a rectangular waveguide, a microstrip probe, an impedance conversion line and a 50-ohm microstrip transmission line.

[0116] The microstrip probe, impedance transformation line and 50 ohm microstrip transmission line are all made on a dielectric substrate;

[0117] The bottom surface of the dielectric substrate is fixed in the rectangular waveguide by welding; the Ka-band signal is input from the rectangular waveguide port, mode-converted through a microstrip probe and an impedance conversion line, and finally outputted from a 50-ohm transmission line.

[0118] Designed according to actual needs Figure 1 The waveguide-to-microstrip HFSS model shown in the figure, Figure 2 The waveguide-to-microstrip assembly is shown.

[0119] 2. About power synthesis:

[0120] The power divider and the power combiner are a pair of reciprocal components, and their circuit principles and external structures are exactly the same. They are collectively referred to as combiners below.

[0121] There are many ways to combine power:

[0122] (1) From the perspective of physical structure, it can be divided into microstrip synthesis circuit, coaxial synthesis circuit and waveguide synthesis circuit;

[0123] (2) In principle, it can be divided into traditional binary synthesis and array-based direct space synthesis.

[0124] These two methods have their own advantages and disadvantages. Generally, when there are less than 8-way synthesis and the ambient temperature requirements are high, binary microstrip synthesis is often used; but when pursuing high power and miniaturization, chip array spatial power synthesis is mostly used, such as coaxial spatial power synthesis and waveguide spatial power synthesis;

[0125] Waveguide spatial power synthesis can be divided into array waveguide spatial synthesis and waveguide radial power synthesis.

[0126] In actual engineering design, when high-power chips are used for power synthesis, combined with structural processing and heat dissipation design, power synthesis is generally carried out in the following forms, such as ET, HT, magic T, array waveguide spatial synthesis and waveguide radial power synthesis.

[0127] 3. The spatial power synthesis scheme adopted by the present invention:

[0128] The present invention adopts the ET waveguide synthesizer solution to perform spatial power synthesis; in the Ka20W final stage circuit module, the ET waveguide synthesizer is adopted to perform spatial power synthesis.

[0129] The present invention adopts independent spatial synthesis technology and uses domestic low-power gallium nitride chips to develop high-efficiency high-power power amplifiers, which solves the difficult problems of high power, long life, high efficiency and high linearity required by the millimeter wave of the communication gateway station, realizes full localization, and can meet the requirements of the current and future millimeter wave power amplifiers of the communication gateway station for large bandwidth, multiple carriers and complex modulation methods.

[0130] like Figure 3 (ET surface waveguide power divider / synthesizer 3D model diagram) and Figure 4 (ET's waveguide synthesizer assembly diagram) as shown:

[0131] (1) The first key to the power amplifier module:

[0132] Since the four-way power single-card module waveguide BJ320 of the Ka-band 20W circuit module amplifier unit requires the use of a microstrip circuit, a microstrip waveguide transition needs to be made at the output end of each amplifier single card. The synthesis loss of the entire ET waveguide synthesizer solution is directly related to the production of a microstrip waveguide transition at the output end. This is the first key.

[0133] Therefore, the present invention adopts the above-mentioned microstrip waveguide probe solution, which has sufficient frequency band width, is easy to load and unload, and is convenient to debug. The synthesizer adopts symmetrical design and precision machine processing to ensure the balance of each branch of the synthesizer in phase and amplitude; an E-plane waveguide T-connector is used to reduce insertion loss. Three-dimensional electromagnetic simulation is performed on waveguide discontinuity and microstrip probe transition to achieve better impedance matching.

[0134] like Figure 3 The 3D model of the ET surface waveguide power divider / combiner is shown.

[0135] (2) The second key to the power amplifier module:

[0136] Another key to designing the power amplifier module is the design of the impedance matching network:

[0137] In the design of any power amplifier module, an incorrect impedance matching network will make the circuit unstable, reduce circuit efficiency and increase nonlinear distortion.

[0138] When designing the matching circuit of a power amplifier module, the matching circuit should simultaneously meet multiple requirements such as matching, harmonic attenuation, broadband, small standing wave, linearity and practical size.

[0139] The output matching circuit should mainly have the functions of low loss, high harmonic suppression, improved standing wave ratio, increased output power and improved nonlinearity. After the output matching circuit is determined, the output power and efficiency of the power amplifier module are basically determined, but its gain flatness does not necessarily meet the index requirements. This requires a reasonable design of the input matching circuit so that the gain flatness meets the requirements.

[0140] When designing the input matching circuit, it is also considered that the input standing wave ratio cannot be too large.

[0141] like Figure 4 Diagram of the ET's waveguide combiner assembly shown.

[0142] 4. Specific issues of Ka20W final circuit module:

[0143] The millimeter wave signal is 29.4GHz~31GHz and the power is -5dBm. It is amplified by 26.5dBm in the Ka pre-amplifier module and enters the Ka20W final circuit module.

[0144] The Ka20W final circuit module is composed of four 8-watt gallium nitride (GaN) chips for spatial power synthesis; in the case of pursuing high power, power synthesis is mostly used. The performance of power synthesis plays a direct and decisive role in the efficiency of the power amplifier, which ultimately leads to high power consumption and difficult thermal design of the power amplifier.

[0145] 5. Solution to power synthesis problem:

[0146] The present invention adopts the ET space power synthesis method; since the power amplifier module of this project pursues miniaturization, the difficulty of its power amplifier power synthesis is the instability problem of the electromagnetic field in the miniaturized structure and the processing problem of related structural parts.

[0147] The signal output from the Ka front-stage circuit module is 29.4GHz~31GHz, and the output power is 26.5dBm; entering the Ka20W final-stage circuit module, the final-stage circuit is composed of four 8-watt gallium nitride (GaN) TGA2595s. The gallium nitride (GaN) TGA2595 provides a small signal gain of 30dB at 27.5~31GHz, a power gain of 17dB, a typical output power greater than 39dBm, and a third-order intermodulation of 33dBm at dual-tone output, less than 30dBc, with an adjustable power supply gate voltage of -2.5V and a drain voltage of 20V;

[0148] Each single-channel amplifier Fig.13 The Ka final stage 20W circuit assembly diagram and the enlarged view Figure 13-1 The enlarged view of H is shown below:

[0149] Gallium nitride (GaN) TGA2595 U10 and chip capacitors and C45, C46, ​​C47, C48, C49, C50 chip capacitors JCS11B-15-UX-50V-101M and C41, C42, C43, C44 chip capacitors JCS11B-30-UX-50V-102M, eutectic on Z9 carrier molybdenum copper carrier Ka20W carrier 1 14mm×3.64mm×1mm, 4 gallium nitride (GaN) monoliths are assembled together on the synthesizer;

[0150] The efficiency of the four-way ET spatial power synthesis method is mainly determined by two factors:

[0151] First, the difficulty of power synthesis of the power amplifier lies in the instability of the electromagnetic field in the miniaturized structure and the processing problem of related structural parts;

[0152] Second, the gain and phase consistency of the four gallium nitride (GaN) TGA2595 active single-card modules, especially the phase consistency requirement of ±5°, can improve the synthesis efficiency;

[0153] Specific solution:

[0154] (1) Solution to the first problem:

[0155] In view of these two factors, the processing progress of the first synthesizer structure mainly depends on the external processing and instrument processing progress, and it is impossible to improve the efficiency through artificial means;

[0156] The power combination problem can be improved by controlling the accuracy and flatness of structural parts processing.

[0157] At present, the mass-produced power splitters and combiners are all processed by the precision division of the institute, and their processing accuracy and flatness can be controlled to 0.02mm, which is highly feasible.

[0158] (2) Solution to the second problem:

[0159] However, the second factor, GaN single-card phase matching, can use an independent test fixture to manually test the phase before synthesis; manual matching greatly improves synthesis efficiency and is conducive to mass production.

[0160] Active single card fixture assembly such as Figure 5 As shown. Figure 5 As shown, the box body 1 includes a box body 1, a box body 2 and a cover plate 3.

[0161] according to Figure 5 The active single card fixture shown in the figure fixes each gallium nitride (GaN) TGA2595 active single card module on the fixture with screws, and then powers on to test the indicators. First, add a gate voltage of about -2.5V, then add a drain voltage of +20V. The gate voltage can be adjusted appropriately.

[0162] In this way, the microwave index of the GaN TGA2595 active single card module will also change, and the corresponding active single card static current will also change, but the static current change range is between 280mA and 580mA. Figure 5 (Active single card fixture assembly structure diagram) for testing.

[0163] 1) The testing process is as follows:

[0164] Before power-on testing, attach a layer of thermal pad to the heat dissipation surface of the card to ensure good heat dissipation of the card;

[0165] Place the single card on the heat sink, install microstrip to coaxial connectors at the input and output ends, connect the input end to the vector network input end, and connect the output end to the vector network output end with a 30dB attenuator.

[0166] Single card power-on: first add gate voltage -3V to the power supply end, then add drain voltage +202V to the power supply end; at this time, the leakage current is very small, about 0.05A; turn on the vector network input signal;

[0167] Test gain parameters: fine-tune the gate voltage (from -3V) after power-on, and fine-tune the gate voltage until the vector network shows that the gain at 29.4GHZ is 29db. Record the gain and phase at 29.4Ghz, 30.2Ghz, and 31Ghz, and record the corresponding gate voltage value and static current;

[0168] The power meter tests the output power of a single card: select the grid voltage when the gain of the single card is 29dB, at this time the DC regulated power supply is +20V with a current limit of 1A, the signal source and the driving amplifier push the single card power, the driving amplifier is powered on in sequence -5V (current limit 0.1A), +6.3V (current limit 2A), +10V (current limit 2.5A), turn on the signal source signal switch -30dBm, at the beginning of power-on, the current is limited to 1A, when the power is pushed to 30dBm, the current is limited to 5A, record the single card output power at 29.4Ghz, 30.2Ghz, and 31Ghz, the single card output power is ≥39dBm.

[0169] When measuring power, if the input signal source increases by 1dB and the power value displayed by the output power meter increases by less than 0.3dB, the power cannot be pushed.

[0170] Turn off +10V, +6.3V, +20V, -5V and single card grid voltage in sequence, making sure to turn off the positive power first and then the negative power;

[0171] Record the test data in Appendix 3. And use a marker to record the test index phase on the bottom of the single card.

[0172] The tested single card is placed upside down in an anti-static box and transferred to the next process.

[0173] When matching single cards, ensure that the phase difference of every 4 single cards is ±5°, as shown in Figure 6, a schematic diagram of active single card testing. Figure 6 includes: Figure 6-1 This is the active single card phase gain test block diagram; Figure 6-2 This is the block diagram of the active single card output power test.

[0174] (3) Methods for solving the power synthesis problem and the beneficial effects achieved:

[0175] 1) Solutions to solve the power synthesis problem:

[0176] The above technical solution solves the problem that the synthesizer process precision does not meet the requirements and the multi-chip power synthesis chip consistency problem leads to low synthesis efficiency;

[0177] To solve the problem that the synthesizer processing accuracy does not meet the requirements, the following methods are mainly adopted:

[0178] a. Carry out simulation design and structural design in advance, and conduct trial processing to reduce risks after evaluation;

[0179] b. Outsourcing processing to avoid risks;

[0180] To solve the problem of chip consistency of multi-chip power synthesis, the following methods are mainly adopted:

[0181] a. Inform the Materials Department that the amplifier chips purchased must meet the same batch requirements;

[0182] b. The power amplifier chips are from the same batch during micro-assembly;

[0183] c. 100% normal temperature performance screening of power amplifier single card;

[0184] d. During synthesis, single cards with good electrical property consistency after screening are used for assembly.

[0185] 2) Beneficial effects of solving the power synthesis problem:

[0186] Four gallium nitride (GaN) TGA2595 active single-card modules, each with an output power greater than 39dBm, are synthesized through four ET waveguides. Theoretically, the synthesis loss is 0.3dB, and the actual test shows that it is less than 0.5dB. Therefore, the output power is 39+5.5=44.5dBm (28W), which meets the design specifications.

[0187] After the above design scheme is adopted, the output power of the operating frequency of 29.4GHz~31GHz is greater than 30W, the gain is greater than 45dB, and the third-order intermodulation (two-tone output is tested 3dB lower than the rated power) is less than -25dBc; the high and low temperature gain variation is less than 3dB (working environment temperature -40℃~+55℃), and the in-band gain flatness is less than 2dB.

[0188] 3. Design of the production process of the present invention:

[0189] The invention mainly consists of a Ka20WPAM type Ka-band 20W power amplifier-control module, a Ka20WPAM type Ka-band 20W power amplifier-feeding module, a Ka20W drive amplifier microwave circuit module, a Ka20W power amplifier microwave circuit module, a Ka20W power amplifier complete machine module and the like.

[0190] In order to achieve the same invention purpose as the above technical solution, the present invention also provides a production process of the above-mentioned Ka-band 20W solid-state power amplifier, and its technical solution is:

[0191] 1. The production process of this product:

[0192] The production process mainly includes circuit board sintering, component sintering, electrical welding, vapor phase cleaning, eutectic, gluing, wire bonding, submodule adjustment and testing, whole machine assembly, whole machine adjustment and testing, environmental testing and other process procedures;

[0193] All processes can be completed in standard process lines and environmental laboratories.

[0194] The process flow chart of each module is as follows: Figure 7 , Figure 8 and Fig. 9 As shown; among them, Figure 7 It is a process flow chart of Ka20WPAM type Ka-band 20W power amplifier-control module and Ka20WPAM type Ka-band 20W power amplifier-feed module; Figure 8 It is the process flow chart of Ka20W drive and amplifier microwave circuit module and Ka20W power amplifier microwave circuit module; Fig. 9 This is the process flow chart of the Ka20W power amplifier complete module.

[0195] 2. Main process technology content:

[0196] (1) Bare chip eutectic welding process:

[0197] The product is a module made using microwave hybrid integrated circuit technology. According to the product performance characteristics, it has high reliability and high stability. Due to the use of high-power gallium nitride bare chip design, the chip surface temperature will reach about 170°C when working at high temperature, so the eutectic process is adopted.

[0198] Eutectic welding has sufficient grounding, which makes it easier for chip heat to dissipate, increases the heat dissipation speed of power chips, and plays a great role in improving the reliability and stability of components.

[0199] (2) Gold wire bonding process:

[0200] In the gold wire bonding process, the chip device is sintered to the metal shielding box, and the gold wire bonding process is used to achieve electrical interconnection, and the corresponding points on the dielectric circuit board are connected to the corresponding wiring points of the bare chip, so that the module has the function of a circuit. This product uses gold wire for bonding, and wedge welding has the advantages of flexible welding direction, fast welding speed and higher welding strength than other welding methods.

[0201] (3) Sintering process:

[0202] In order to ensure good grounding between the circuit board and the metal carrier of the ground plate, and to effectively utilize the assembly space and make the electronic equipment miniaturized and lightweight, the sintering process is adopted; the characteristics of the sintering process are: reducing crosstalk between signals; reducing signal transmission loss and signal transmission delay time; small circuit parasitic parameters, low noise, good high-frequency characteristics and other excellent electrical properties.

[0203] 3. Key process settings and control methods:

[0204] The gold wire bonding in this product is a very important link in the entire product manufacturing. The bonding quality (including bonding temperature, bonding strength, and bonding pressure) will affect the electrical characteristics and reliability of the product. Therefore, this gold wire bonding link is set as a key process.

[0205] The testing equipment used in key processes is specified to be thermometers, dynamometers and tensile testers. The specified professional operators have undergone on-the-job training and have job certificates.

[0206] The gold wire bonding process requirements are as follows:

[0207] (1) Before formal production, use a force gauge to measure the bonding pressure three times. The pressure is required to be between (30 and 40) g. Then, 10 gold wires are bonded on the same substrate to test their bonding strength. The minimum bonding strength is required to be 3.5 g, and the average bonding strength is not less than 5 g.

[0208] (2) Bonding order: Chip first, that is, the first bonding point is on the chip, usually divided into GaAs chip to chip capacitor, GaAs chip to Rogers, GaAs chip to GaAs chip, chip capacitor to chip capacitor, etc.;

[0209] (3) 25.4μm gold wire bonding heating stage temperature: 100℃±5℃, splitting force 18~24gf, wire bonding.

[0210] 4. Conclusion of the production process of the present invention:

[0211] According to the above overall process plan, combined with the actual process difficulty, the process plan can meet the requirements of the design technical indicators. Adopting the preferred process plan can achieve products that meet the performance indicators and are conducive to mass production.

[0212] In summary, from indicator decomposition and formulation to core technology research, the present invention analyzes the technical difficulty and key technical problems in detail, and proposes practical solutions, which are implemented in steps and are fully feasible, ultimately achieving the goal of a sample product.

[0213] IV. Technical effects achieved by the present invention: Compared with the prior art, the present invention has the following advantages:

[0214] 1. Ka-band 30W solid-state power amplifier, with excellent module microwave indicators, operating frequency 29.4GHz ~ 31GHz, output power greater than 30W, gain greater than 45dB, third-order intermodulation (two-tone output 3dB lower than rated power test) less than -25dBc; high and low temperature gain variation less than 3dB (working environment temperature -40℃ ~ +55℃), in-band gain flatness less than 2dB;

[0215] 2. The Ka-band 20W solid-state power amplifier module adopts ET spatial power synthesis technology and has the characteristics of high synthesis efficiency;

[0216] 3. Use gallium nitride (GaN) active single-card microwave index test for phase matching technology to improve synthesis efficiency;

[0217] 4. Adopting the optimal process scheme can achieve products that meet performance indicators and facilitate mass production.

[0218] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A Ka-band 20W solid-state power amplifier, characterized in that: The solid-state power amplifier includes a Ka front-stage circuit module, a Ka20W final-stage circuit module and a Ka power supply module; the Ka front-stage circuit module includes an input power detector, a temperature-compensated attenuator, and an amplifier, and its output power is greater than 5W; the Ka20W final-stage circuit module is composed of four 8-watt gallium nitride (GaN) chips for spatial power synthesis; the Ka power supply module provides power supply voltage for the Ka front-stage circuit module and the Ka20W final-stage circuit module.

2. The Ka-band 20W solid-state power amplifier according to claim 1, characterized in that: The Ka front-stage circuit module has a millimeter wave signal of 29.4GHz to 31GHz and a power of -5dBm. After passing through the RF connector, it enters the Ka-band power divider and then becomes two signals. The power of the two equal-amplitude signals is -8.5dBm.

3. The Ka-band 20W solid-state power amplifier according to claim 2, characterized in that: The first signal of the two signals enters the input power detector for input detection processing to detect the input model size, and the detected analog signal is sent to the external host computer module for processing, thereby determining the input power size of the input signal.

4. The Ka-band 20W solid-state power amplifier according to claim 2, characterized in that: The second signal of the two signals enters the radio frequency branch, and the signal enters the first-stage temperature-compensated attenuator; then, the signal continues to enter the first-stage equalizer; and the signal enters the first-stage amplifier again; The signal enters the second-stage equalizer again; the signal enters the second-stage temperature-compensated attenuator; the signal finally enters the driver amplifier.

5. The Ka-band 20W solid-state power amplifier according to claim 1, characterized in that: In the Ka20W final stage circuit module, ET's waveguide synthesizer is used to perform spatial power synthesis.

6. The Ka-band 20W solid-state power amplifier according to claim 1, characterized in that: The signal output from the Ka front-stage circuit module is 29.4GHz~31GHz, with an output power of 26.5dBm; it enters the Ka20W final-stage circuit module; at 27.5~31GHz, it provides a small signal gain of 30dB, a power gain of 17dB, a typical output power greater than 39dBm, and a third-order intermodulation of 33dBm at dual-tone output, less than 30dBc, the power supply gate voltage is adjustable at -2.5V, and the drain voltage is 20V.

7. The Ka-band 20W solid-state power amplifier according to claim 5, characterized in that: The GaN single card phase matching adopts an independent test fixture to perform manual phase testing before synthesis. After each GaN active single card module is fixed to the test fixture by screws, power is applied to test the indicators, first adding a gate voltage of about -2.5V, and then adding a drain voltage of +20V. The gate voltage can be adjusted appropriately. Therefore, the microwave indicators of the GaN active single card module will also change, and the corresponding active single card static current will also change. The static current change range is between 280mA and 580mA, and the test is performed. The test process is as follows: Before power-on testing, attach a layer of thermal pad to the heat dissipation surface of the card to ensure good heat dissipation of the card; Place the single card on the heat sink, install microstrip to coaxial connectors at the input and output ends, connect the input end to the vector network input end, and connect the output end to the vector network output end with a 30dB attenuator. Single card power-on: first add gate voltage -3V to the power supply end, then add drain voltage +202V to the power supply end; at this time, the leakage current is very small, 0.05A; turn on the vector network input signal; Test gain parameters: fine-tune the gate voltage from -3V after power-on; fine-tune the gate voltage until the vector network displays 29.4GHz and the gain is 29db, record the gain and phase of 29.4Ghz, 30.2Ghz, and 31Ghz, and record the corresponding gate voltage value and static current; The power meter tests the output power of a single card: select the grid voltage when the gain of the single card is 29dB, at this time, the DC regulated power supply +20V current limit 1A, the signal source and the driving amplifier push the single card power, the driving amplifier is powered on in sequence -5V, current limit 0.1A; +6.3V, current limit 2A, +10V, current limit 2.5A; turn on the signal source signal switch -30dBm, at the beginning of power on, the current limit is 1A; when the power is pushed to 30dBm, the current is limited to 5A, and the single card output power at 29.4Ghz, 30.2Ghz, and 31Ghz is recorded. The output power of the single card is ≥39dBm; When measuring power, if the power value displayed by the output power meter increases by less than 0.3dB when the input signal source increases by 1dB, the power cannot be pushed; Turn off +10V, +6.3V, +20V, -5V and single card grid voltage in sequence, making sure to turn off the positive power first and then the negative power; Record the test data in a table and use a marker to record the test index phase on the bottom of the single card; After the test is passed, the single card is placed upside down in an anti-static box and transferred to the next process.

8. The production process of a Ka-band 20W solid-state power amplifier according to any one of claims 1 to 7, characterized in that: The production process mainly includes the following steps: circuit board sintering, component sintering, electrical assembly welding, vapor phase cleaning, eutectic, gluing, gold wire bonding, submodule adjustment and testing, whole machine assembly, whole machine adjustment and testing, and environmental testing.

9. The production process of the Ka-band 20W solid-state power amplifier according to claim 8, characterized in that: In the gold wire bonding process, the chip device is sintered to the metal shielding box, the gold wire bonding process is used to achieve electrical interconnection, and the corresponding points on the dielectric circuit board are connected to the corresponding wiring points of the bare chip, so that the module has the function of a circuit.

10. The production process of the Ka-band 20W solid-state power amplifier according to claim 8, characterized in that: The gold wire bonding process requirements are as follows: 1) Before formal production, use a dynamometer to measure the bonding pressure three times, and the pressure is required to be between 30 and 40g. Then bond 10 gold wires on the same substrate to test their bonding strength. The minimum bonding strength is required to be 3.5g, and the average bonding strength is not less than 5g. 2) Bonding order: Chip first, that is, the first bonding point is on the chip, usually divided into GaAs chip to chip capacitor, GaAs chip to Rogers, GaAs chip to GaAs chip, chip capacitor to chip capacitor; 3) 25.4μm gold wire bonding heating stage temperature: 100℃±5℃, wedge force is 18~24gf, wire bonding.

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