Wide-temperature high-precision GaN amplifier grid voltage compensation circuit

Abstract

The invention discloses a wide-temperature high-precision GaN amplifier grid voltage compensation circuit, and belongs to the technical field of amplifiers. Comprising a filtering unit, the input end of the filtering unit is connected with an external power supply, and the output end of the filtering unit is connected with the input end of a voltage stabilizing unit; the output end of the voltage stabilizing unit is connected with the voltage following unit, the potentiometer DW1 and the temperature compensation unit; the input end of the voltage following unit is connected with the temperature compensation unit, and the output end of the voltage following unit is connected with an external circuit; the potentiometer DW1 is connected with the temperature compensation unit; the initial voltage of the emitter junction voltage of the transistor Q1 in the temperature compensation unit is preset by changing the ratio of all resistors in the potentiometer DW1, and the change of the gate voltage initial value of the GaN amplifier is realized. The compensation circuit composed of simple and low-cost components performs high-precision compensation on the grid voltage of the GaN amplifier, and has the characteristics of high practicability, simplicity in operation, low cost, convenience in internal integration and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of amplifiers, and in particular to a wide-temperature high-precision GaN amplifier gate voltage compensation circuit. Background Art

[0002] In recent years, active radar technology has developed rapidly, and the dynamic range of the signal received by the antenna port has become higher and higher, requiring the receiving module to have strong anti-interference ability, high dynamic, low noise, high P -1 The noise and high P value of existing GaAs amplifiers are affected by device characteristics. -1 It is difficult to take both values ​​into account; under certain working conditions, GaN amplifiers can solve the above problems very well. In actual project applications, it was found that the gain fluctuation of GaN amplifiers at high and low temperatures (-45℃~+85℃) was large (3dB-7dB), which could not meet the application requirements of the receiving module for high and low temperature fluctuations (less than 2dB). Through experimental verification, it was found that the reason for the large gain fluctuation of GaN amplifiers is that the static operating point current of the device itself changes with temperature. The static operating point of the GaN amplifier is determined by its gate voltage. Changing the gate voltage value under high and low temperature conditions can solve the problem of large gain fluctuation of the receiving module.

[0003] The following problems exist in the prior art: 1. The function of changing the gate voltage can be achieved through thermistors. The change curves of low temperature (-45°C) and high temperature (+85°C) of this method are large and exponential, which does not conform to the gate voltage change trend of the amplifier, and the improvement effect is not obvious. 2. The gate voltage compensation circuit composed of voltage stabilizers, DA chips, temperature sensors, etc. is complex, requires many devices, is large in size, and has high cost. It requires external software for control and cannot be applied to existing module components; 3. The gate voltage of the amplifier is adjusted by adjusting the power load of the test board and the external power supply. It is costly and large in size and cannot meet the discreteness of the temperature characteristics of the power amplifier. 4. The amplifier is detected by a current detection device, detected by a microprocessor, and then the gate voltage is output through a DA chip. The circuit is also complex and costly. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a high-precision GaN amplifier gate voltage compensation circuit with a wide temperature range.

[0005] The objective of the present invention is achieved through the following technical solutions: a wide temperature and high-precision GaN amplifier gate voltage compensation circuit, comprising a filter unit, the input end of the filter unit is connected to an external power supply, the output end of the filter unit is connected to the input end of a voltage stabilizing unit; the output end of the voltage stabilizing unit is connected to a voltage following unit, a potentiometer DW1 and a temperature compensation unit; the input end of the voltage following unit is connected to the temperature compensation unit, and the output end of the voltage following unit is connected to an external circuit; the potentiometer DW1 is connected to the temperature compensation unit; under the action of an external power supply, current passes through the filter unit, the voltage stabilizing unit, the potentiometer DW1, the temperature compensation unit and the voltage following unit, and the initial voltage of the emitter junction voltage of the transistor Q1 in the temperature compensation unit is preset by changing the ratio of each resistor in the potentiometer DW1, thereby realizing a change in the initial value of the gate voltage of the GaN amplifier.

[0006] Preferably, the filtering unit includes a first inductor L1 and a first capacitor C1; the first end of the first inductor L1 is connected to an external power supply, the second end of the first inductor L1 is connected to the first end of the first capacitor C1 and the input end of the voltage stabilizing unit, and the second end of the first capacitor C1 is connected to the ground GND.

[0007] Preferably, the voltage stabilizing unit includes a low voltage dropout linear regulator LDO and a first resistor R1; the first end of the low voltage dropout linear regulator LDO is connected to the output end of the filtering unit, and the second end of the low voltage dropout linear regulator LDO is connected to the first end of the first resistor R1, the voltage following unit and the temperature compensation unit; the second end of the first resistor R1 is connected to the potentiometer DW1.

[0008] Preferably, the potentiometer DW1 includes a second resistor R2 and a third resistor R3; the first end of the second resistor R2 is connected to the output end of the voltage stabilizing unit, the second end of the second resistor R2 is connected to the first end of the third resistor R3 and the temperature compensation unit; the second end of the third resistor R3 is connected to the temperature compensation unit.

[0009] Preferably, the temperature compensation unit includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a transistor Q1; the first ends of the fourth resistor R4 and the fifth resistor R5 are connected to the potentiometer DW1, the second end of the fourth resistor R4 is connected to the first end of the eighth resistor R8 and the ground GND, and the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6 and the voltage follower unit; the second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7, the first end of the ninth resistor R9 and the base of the transistor Q1; the second end of the seventh resistor R7 is connected to the second end of the eighth resistor R8 and the emitter of the transistor Q1; the second end of the ninth resistor R9 is connected to the output end of the voltage stabilizing unit and the collector of the transistor Q1.

[0010] Preferably, the voltage follower unit includes an operational amplifier IC1, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second capacitor C2 and a third capacitor C3; the negative power supply terminal VEE of the operational amplifier IC1 is connected to the output end of the voltage stabilizing unit, the positive input end of the operational amplifier IC1 is connected to the temperature compensation unit, the negative input end of the operational amplifier IC1 is connected to the tenth resistor R10, the second capacitor C2, the third capacitor C3 and the first end of the twelfth resistor R12, the positive power supply terminal VCC of the operational amplifier IC1 is connected to the ground GND, the output end of the operational amplifier IC1 is connected to the tenth resistor R10, the second capacitor C2, the third capacitor C3 and the first end of the eleventh resistor R11; the second ends of the eleventh resistor R11 and the twelfth resistor R12 are connected to the external circuit.

[0011] Preferably, the transistor Q1 is of PNP type.

[0012] The beneficial effects of the present invention are: 1) The gate voltage of the GaN amplifier is compensated with high precision through a compensation circuit composed of simple and low-cost components, which has the characteristics of strong practicality, simple operation, low cost, and easy internal integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the schematic diagram of the gate voltage compensation circuit of a wide temperature and high precision GaN amplifier; Figure 2 This is the current topology diagram of the gate voltage compensation circuit of the wide temperature and high precision GaN amplifier; Figure 3 It is the simulation diagram of different slope rates of the power amplifier grid voltage; Figure 4 This is the printed circuit board diagram of the wide temperature and high precision GaN amplifier gate voltage compensation circuit. DETAILED DESCRIPTION

[0014] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0015] See also Figure 1-Figure 4The present invention provides a technical solution: a wide temperature and high precision GaN amplifier gate voltage compensation circuit, comprising a filter unit, wherein the input end of the filter unit is connected to an external power supply, and the output end of the filter unit is connected to the input end of a voltage stabilizing unit; the output end of the voltage stabilizing unit is connected to a voltage following unit, a potentiometer DW1 and a temperature compensation unit; the input end of the voltage following unit is connected to the temperature compensation unit, and the output end of the voltage following unit is connected to an external circuit; the potentiometer DW1 is connected to the temperature compensation unit; under the action of the external power supply, current passes through the filter unit, the voltage stabilizing unit, the potentiometer DW1, the temperature compensation unit and the voltage following unit, and the initial voltage of the emitter junction voltage of the transistor Q1 in the temperature compensation unit is preset by changing the ratio of each resistor in the potentiometer DW1, thereby realizing the change of the initial value of the gate voltage of the GaN amplifier.

[0016] In this embodiment, the current change characteristics brought about by the high and low temperature impedance changes of the transistor are converted into voltage changes in the compensation circuit, thereby realizing the adjustment of the gate voltage of the GaN amplifier under high and low temperature conditions. The operational amplifier in the circuit provides sufficient driving capability for the circuit output gate voltage value to ensure that the amplifier can work normally; the voltage divider resistor and potentiometer inside the circuit can adjust the slope and high-precision adjustment of the gate voltage value under high and low temperature conditions, which can adapt to the gate voltage difference of the GaN amplifier; a low-dropout linear regulator (LDO) can be added to the circuit to adapt to changes in the external input voltage within a certain range. By selecting devices with different and higher temperature ranges, it can adapt to the use requirements of a wider range of temperatures. The compensation circuit of this patent cleverly utilizes the temperature change characteristics of the transistor, completes the voltage adjustment through the voltage divider circuit, and solves the problem of applicability of the receiving module project. The application background of the present invention is that a certain high-dynamic receiving module requires an output P-1 value (typical value 35dBm). The GaN amplifier used in the link can meet the P-1 value requirement, but there is a problem of large gain fluctuation under high and low temperature conditions. After investigation, it was found that the high and low temperature gain of the GaN amplifier has a large difference (3dB -7dB), and effective compensation cannot be achieved through the traditional temperature compensation circuit (the discreteness of the amplifier causes uncertainty in compensation). By improving the gate voltage value of the GaN amplifier under high and low temperature conditions, the gain value of the GaN amplifier can be improved, achieving the predetermined effect and meeting the working state requirements of the receiving module.

[0017] The circuit is mainly composed of core devices such as operational amplifiers, PNP transistors, potentiometers, LDOs, and other devices are common components such as capacitors, resistors, and inductors. In summary, the cost of the entire circuit is low. According to the characteristics of the PNP transistor impedance changing with temperature, based on the formula U=R*I, using the circuit voltage division working principle, when the external input U value of the compensation circuit remains unchanged, the working current of the transistor changes. Based on the adjustment of the peripheral device parameters of this circuit, the temperature characteristics of the transistor are transferred to the required voltage (GaN amplifier gate voltage) according to a certain rule, and then the adjustment of the static operating point of the GaN amplifier is realized, and the high and low temperature gain of the receiving module is adjusted to meet the actual engineering use requirements. In order to ensure that the compensation circuit has sufficient driving capability for the gate voltage of the GaN amplifier, the same-direction voltage follower function of the operational amplifier is used to ensure that the gate voltage obtained by the compensation circuit can meet the actual needs of the GaN amplifier. In order to adapt to the individual differences of GaN amplifiers, the potentiometer can be used to make subtle adjustments to the working current of the PNP transistor to achieve the minimum 0.001V precision control of the GaN amplifier gate voltage. In order to adapt to the fluctuation of external power supply voltage, a low-dropout linear regulator (LDO) is introduced into the circuit, which can realize ultra-low voltage difference voltage conversion, and at the same time ensure the accuracy and stability of its output voltage, thereby ensuring the consistency of the circuit. In general, the present invention has the advantages of strong practicality, high precision, simple operation, low cost, easy internal integration and transplantation, and solves the problem of large gain fluctuation of GaN amplifiers under high and low temperature conditions.

[0018] In some embodiments, the filtering unit includes a first inductor L1 and a first capacitor C1; the first end of the first inductor L1 is connected to an external power supply, the second end of the first inductor L1 is connected to the first end of the first capacitor C1 and the input end of the voltage stabilization unit, and the second end of the first capacitor C1 is connected to the ground GND.

[0019] In this embodiment, L1 and C1 in the circuit filter the input external negative voltage, reduce the ripple of the input power supply, and improve the quality of the circuit.

[0020] In some embodiments, the voltage stabilizing unit includes a low voltage dropout linear regulator LDO and a first resistor R1; the first end of the low voltage dropout linear regulator LDO is connected to the output end of the filtering unit, and the second end of the low voltage dropout linear regulator LDO is connected to the first end of the first resistor R1, the voltage following unit and the temperature compensation unit; the second end of the first resistor R1 is connected to the potentiometer DW1.

[0021] In this embodiment, in order to improve the adaptability of the circuit, a low dropout linear regulator (LDO) is added. By adopting a linear regulation method, the LDO can work stably when the input voltage is close to the output voltage, perform low voltage conversion, and ensure the accuracy and stability of the output voltage. The LDO can provide a stable DC voltage output with the advantages of low noise, low ripple and low cost. The LDO currently used in the circuit can adapt to a wide range of voltages from -5V to -10V to meet the application of different circuits.

[0022] In some embodiments, the potentiometer DW1 includes a second resistor R2 and a third resistor R3; the first end of the second resistor R2 is connected to the output end of the voltage stabilizing unit, the second end of the second resistor R2 is connected to the first end of the third resistor R3 and the temperature compensation unit; the second end of the third resistor R3 is connected to the temperature compensation unit.

[0023] In this embodiment, according to the characteristics of the potentiometer DW1, it is decomposed into resistors R2 and R3 in the circuit. By designing the compensation circuit, the initial value of the static voltage of the transistor Q1 can be preset and adjusted by changing the ratio of R2 and R3.

[0024] In some embodiments, the temperature compensation unit includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a transistor Q1; the first ends of the fourth resistor R4 and the fifth resistor R5 are connected to the potentiometer DW1, the second end of the fourth resistor R4 is connected to the first end of the eighth resistor R8 and the ground GND, and the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6 and the voltage follower unit; the second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7, the first end of the ninth resistor R9 and the base of the transistor Q1; the second end of the seventh resistor R7 is connected to the second end of the eighth resistor R8 and the emitter of the transistor Q1; the second end of the ninth resistor R9 is connected to the output end of the voltage stabilizing unit and the collector of the transistor Q1.

[0025] In this embodiment, resistors R5 and R6 are devices that need to be debugged in this circuit. By changing their values, the initial value of the static voltage of Q1 can be preset and adjusted. Transistor Q1 is a PNP type. The change of its base current can control the change of collector current. Its current amplifier coefficient β will increase with the increase of temperature. The temperature compensation of the gate voltage of the GaN amplifier is realized by applying the negative temperature coefficient of the transistor emitter junction voltage Vbe.

[0026] In some embodiments, the voltage follower unit includes an operational amplifier IC1, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second capacitor C2 and a third capacitor C3; the negative power supply terminal VEE of the operational amplifier IC1 is connected to the output end of the voltage stabilizing unit, the positive input end of the operational amplifier IC1 is connected to the temperature compensation unit, the negative input end of the operational amplifier IC1 is connected to the tenth resistor R10, the second capacitor C2, the third capacitor C3 and the first end of the twelfth resistor R12, the positive power supply terminal VCC of the operational amplifier IC1 is connected to the ground GND, the output end of the operational amplifier IC1 is connected to the tenth resistor R10, the second capacitor C2, the third capacitor C3 and the first end of the eleventh resistor R11; the second ends of the eleventh resistor R11 and the twelfth resistor R12 are connected to the external circuit.

[0027] In this embodiment, the voltage follower function of the operational amplifier IC1 realizes that the output voltage closely follows the input voltage change, and its voltage gain is 1. Combined with the characteristics of high input impedance and low output impedance of the operational amplifier, the impedance characteristics of the circuit can be matched, and the gate voltage compensation circuit can improve the load capacity.

[0028] In some embodiments, the transistor Q1 is of PNP type.

[0029] See also Figure 2 , the equivalent current flow topology diagram of the circuit of the present invention. According to the equivalent circuit of the current of the compensation circuit of the amplifier gate voltage, it can be known that under the action of the external power supply voltage, the current mainly flows through two branches, namely branch 1 and branch 2, and branch 2 mainly includes R1, R2, IQ1, R3, and R4. It can be seen from the circuit topology diagram that by changing the ratio of R2 and R3, the initial voltage of the emitter junction voltage Vbe of Q1 is preset, and at the same time, the change of the resistance value of R2 and R3 causes the change of the current of Q1, which in turn causes the change of the initial voltage of the voltage at the Q1 port, thereby realizing the change of the initial value of the gate voltage of the power amplifier.

[0030] See also Figure 3 , the simulation diagram of the power amplifier gate voltage with different slopes of the present invention. Combined with the current flow topology diagram, it can be known that by changing the ratio of the two resistors R5 and R6, the ratio relationship of the current distribution can be changed, and then the high and low temperature slope of the circuit Q1 emitter junction voltage Vbe can be changed to achieve compensation adjustment of the power amplifier gate voltage. Combined with the high and low temperature impedance characteristics of the transistor Q1, the required gate voltage compensation curve can be obtained. Combined with the adjustment of DW1, the gate voltage value can be adjusted with an accuracy of 0.001V within the range of 2V; under constant gate voltage conditions, high and low temperature adjustment within the range of 0.3V can be achieved.

[0031] See also Figure 4 , the printed circuit board layout of the present invention. It can be seen from the circuit diagram that the circuit occupies a small space, about 35mm*16mm.

[0032] In order to solve the high output P-1 value requirement of the high dynamic receiving module, the problem of large gain fluctuations under high and low temperature conditions after amplification using a GaN amplifier is solved by the present invention through high-precision compensation of the GaN amplifier gate voltage. Due to the strong practicality, simple operation, low cost, and easy internal integration of the invention, the circuit can be applied to other devices or modules according to the needs of different modules, which provides a guarantee for subsequent products to win the market.

[0033] The present invention can be adaptively improved according to specific parameters or needs of the product and in combination with differences in PNP transistor parameters, potentiometers, operational amplifiers, and LDOs.

[0034] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A wide temperature and high precision GaN amplifier gate voltage compensation circuit, characterized in that: It comprises a filtering unit, wherein the input end of the filtering unit is connected to an external power supply, the output end of the filtering unit is connected to the input end of a voltage stabilizing unit; the output end of the voltage stabilizing unit is connected to a voltage following unit, a potentiometer DW1 and a temperature compensation unit; the input end of the voltage following unit is connected to the temperature compensation unit, and the output end of the voltage following unit is connected to an external circuit; the potentiometer DW1 is connected to the temperature compensation unit; under the action of the external power supply, the current passes through the filtering unit, the voltage stabilizing unit, the potentiometer DW1, the temperature compensation unit and the voltage following unit, and the initial voltage of the emitter junction voltage of the transistor Q1 in the temperature compensation unit is preset by changing the ratio of each resistor in the potentiometer DW1, thereby realizing the change of the initial value of the gate voltage of the GaN amplifier.

2. The wide temperature and high precision GaN amplifier gate voltage compensation circuit according to claim 1, characterized in that: The filtering unit includes a first inductor L1 and a first capacitor C1; the first end of the first inductor L1 is connected to an external power supply, the second end of the first inductor L1 is connected to the first end of the first capacitor C1 and the input end of the voltage stabilizing unit, and the second end of the first capacitor C1 is connected to the ground GND.

3. The wide temperature and high precision GaN amplifier gate voltage compensation circuit according to claim 1, characterized in that: The voltage stabilizing unit includes a low voltage dropout linear regulator LDO and a first resistor R1; the first end of the low voltage dropout linear regulator LDO is connected to the output end of the filtering unit, and the second end of the low voltage dropout linear regulator LDO is connected to the first end of the first resistor R1, the voltage following unit and the temperature compensation unit; the second end of the first resistor R1 is connected to the potentiometer DW1.

4. The wide temperature and high precision GaN amplifier gate voltage compensation circuit according to claim 1, characterized in that: The potentiometer DW1 includes a second resistor R2 and a third resistor R3; the first end of the second resistor R2 is connected to the output end of the voltage stabilizing unit, the second end of the second resistor R2 is connected to the first end of the third resistor R3 and the temperature compensation unit; the second end of the third resistor R3 is connected to the temperature compensation unit.

5. The wide temperature and high precision GaN amplifier gate voltage compensation circuit according to claim 1, characterized in that: The temperature compensation unit includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9 and a transistor Q1; the first ends of the fourth resistor R4 and the fifth resistor R5 are connected to the potentiometer DW1, the second end of the fourth resistor R4 is connected to the first end of the eighth resistor R8 and the ground GND, and the second end of the fifth resistor R5 is connected to the first end of the sixth resistor R6 and the voltage follower unit; the second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7, the first end of the ninth resistor R9 and the base of the transistor Q1; the second end of the seventh resistor R7 is connected to the second end of the eighth resistor R8 and the emitter of the transistor Q1; the second end of the ninth resistor R9 is connected to the output end of the voltage stabilizing unit and the collector of the transistor Q1.

6. The wide temperature and high precision GaN amplifier gate voltage compensation circuit according to claim 1, characterized in that: The voltage follower unit includes an operational amplifier IC1, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a second capacitor C2 and a third capacitor C3; the negative power supply terminal VEE of the operational amplifier IC1 is connected to the output end of the voltage stabilizing unit, the positive input end of the operational amplifier IC1 is connected to the temperature compensation unit, the negative input end of the operational amplifier IC1 is connected to the tenth resistor R10, the second capacitor C2, the third capacitor C3 and the first end of the twelfth resistor R12, the positive power supply terminal VCC of the operational amplifier IC1 is connected to the ground GND, the output end of the operational amplifier IC1 is connected to the tenth resistor R10, the second capacitor C2, the third capacitor C3 and the first end of the eleventh resistor R11; the second ends of the eleventh resistor R11 and the twelfth resistor R12 are connected to the external circuit.

7. The wide temperature and high precision GaN amplifier gate voltage compensation circuit according to any one of claims 1 to 6, characterized in that: The transistor Q1 is of PNP type.

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