Gain temperature compensation method and circuit for Ku-band amplifier

Abstract

The invention discloses a gain temperature compensation method and circuit for a Ku-band amplifier, and belongs to the technical field of semiconductor integrated circuits. A Ku wave band power amplifier is formed on the basis of a pHEMT amplification device. A grid temperature compensation bias network is adopted for grid bias of the pHEMT amplifier, and the gain of the amplifier is controlled to fluctuate along with the temperature. According to the fluctuation condition of the gain of the pHEMT amplifier along with the temperature, the resistance value of a temperature compensation resistor in the grid bias network is determined, and the grid bias voltage is divided through the grid temperature compensation resistor. As the resistance value of the thermistor changes along with the temperature, the direct-current voltage output by the grid bias network correspondingly changes along with the temperature, so that the gain is controlled. The problem that the gain of an existing PHEMT technology-based Ku band amplifier changes greatly along with the temperature change is solved, and the situation that the gain of the amplifier is out of tolerance along with the temperature change is avoided. The technical scheme provided by the invention is widely applied to various Ku wave band power amplifiers.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor integrated circuits, and further relates to the technical field of microwave monolithic integrated circuits (MMICs), and in particular, to a Ku-band amplifier gain temperature compensation method and a circuit thereof. Background Art

[0002] GaAs pHEMT Ku-band amplifier integrated circuits in their use environment, the gain change with temperature is an important indicator in the power amplifier design process, such as Figure 1 The Ku-band amplifier of GaAs pHEMT shown in the figure is a typical two-stage amplifier device, with a gate DC power-on network and a drain DC power-on network. The microwave signal is input from the left side, undergoes two-stage amplification, and is output from the right port. The input end has an input matching network, which matches the 50Ω network of the previous stage to the pHEMT input impedance to obtain good input return loss, and performs capacitor isolation to isolate the first-stage gate DC signal from the input end. The output end includes an output matching network, whose function is to match the amplifier output end to the 50Ω network of the subsequent stage and perform capacitor isolation to obtain good output standing wave, and perform DC current isolation on the second-stage drain DC signal from the output end. From input through amplifier to output, pHEMT amplifier is the core device for signal power amplification. It amplifies the input signal in the range of 14GHz-18GHz. The source of the device is grounded through a through-hole made by 0.25um GaAs process. The gate G is input with gate DC bias signal by external power supply through gate bias network. The drain D of the device is input with drain DC bias signal by external power supply through drain bias network. The circuit structure principle is as follows: Figure 1 shown.

[0003] The first-stage pHEMT amplifier device and the second-stage pHEMT amplifier device are connected through an interstage matching network, which is used to match the impedance of the first-stage and second-stage amplifier devices and isolate the drain bias voltage of the first-stage amplifier device from the gate bias voltage of the second-stage amplifier device to ensure that different DC control voltages are independent of each other. The gate bias input voltage VG and the drain bias input voltage VD have been Figure 1 After the second-stage power amplification, the signal is output from the drain to the output end, and reaches the output port through the impedance matching network. The function of the output impedance matching network is to match the circuit impedance to the 50 ohm impedance of the input and output ends. When cascaded with other circuits with a port impedance of 50Ω, a good standing wave can be obtained.

[0004] The amplifier performs power and signal amplification mainly through the pHEMT device, which is controlled by the gate bias voltage and the drain bias voltage. For the amplifier in this scheme, the GaAs 0.25um process is adopted, and the pHEMT gate voltage is -0.6V at room temperature, the drain voltage is 5V, the input signal is set to a continuous wave of -10dBm, and the gain G is 19dB. In the 14GHz-18GHz frequency band, the gain of this amplifier shows a large change with temperature. This makes the overall gain curve show a certain degree of floating within the application frequency band as the chip operating temperature changes, which is very unfavorable for the use of the product when the ambient temperature changes. In this case, it is necessary to consider adding a compensation structure to compensate for the gain temperature characteristics.

[0005] In the Chinese patent database, the patent applications related to the gain flatness of power amplifiers include "Temperature Compensated Power Amplifier Circuit and Compensation Method thereof" with publication number CN116683876A, "Segmented Temperature Compensated Power Amplifier Circuit and Compensation Method thereof" with publication number CN116846345A, "A DC Voltage Acquisition Circuit Based on Temperature Compensation" with publication number CN118209780A, and "Dynamic Load Compensated Analog Multiplier and Temperature Compensated Crystal Oscillator" with publication number CN118276819A. However, to date, there has been no application for optimizing the Ku-band amplifier gain temperature compensation method and circuit using the technical solution described in the present invention.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The technical problem to be solved by the present invention is to solve the problem that the gain of the existing pHEMT process Ku-band amplifier changes greatly with temperature.

[0008] The concept of the present invention: Figure 2 As shown in the figure, based on the Ku-band amplifier structure, a temperature compensation network is introduced at the gate DC voltage supply end. By simulating and optimizing the trend of gain change with temperature and assigning reasonable values, different gate input voltages of pHEMT at different temperatures are obtained, achieving the goal of small gain fluctuation with temperature in the application frequency band of 14GHz-18GHz.

[0009] Description of parameters involved in all formulas of the present invention: Operating frequency: refers to an operating frequency band range, such as 0.8GHz~2GHz, 14GHz~18GHz, 19GHz~23GHz, 29GHz~31GHz, etc.

[0010] Linear gain: It characterizes the chip's amplification factor of the signal when the amplifier is in the linear amplification state. The input power is P2 and the output power is P1, that is, the linear gain G=10lg(P2 / P1)dB. In actual operation, the linear gain is obtained through S parameter testing, that is, the forward transmission coefficient, linear gain G=dB(S(2,1)).

[0011] Gain temperature change ΔG (peak-to-peak): The minimum linear gain G at 25°C within the target frequency band min1 , and the minimum linear gain G at -55℃ and 125℃ min2 The difference: ΔG=G min2 -G min1 .

[0012] dB(): is a function that converts the amplitude and phase form of S parameters into decibel expression.

[0013] 2 and 1 in the S parameters correspond to the output port and input port of the chip under test.

[0014] Linear amplification state: refers to the gain of the channel when the gain does not show compression as the input power increases.

[0015] To this end, the present invention provides a method for Ku-band amplifier gain temperature compensation based on pHEMT process. The method is: (1) Based on pHEMT amplifier devices, a GaAs power amplifier with two or more amplification structures is formed; (2) Introducing a gate bias network (gate temperature compensation network) with resistor thermal modulation technology at the gate of the pHEMT amplifier, and using resistor thermal modulation (temperature compensation) technology to monitor the amplifier gain fluctuation with temperature; (3) The initial values ​​of the parameters of each component in the pHEMT amplifier circuit are obtained by calculation, and the parameters of each device in the circuit are optimized according to the product demand indicators using simulation tools. The two-port S parameters of the amplifier can be obtained through simulation controls. After adjusting the device temperature parameters, the gain at different temperatures is obtained. According to the fluctuation of the gain with temperature, the gate bias network is built and the resistance value of the temperature compensation resistor is determined; (4) The gate bias voltage is divided by the gate temperature compensation resistor. When the ambient temperature changes, the temperature fluctuation of the amplifier gain in the target frequency band of 14.0 GHz-18.0 GHz is weakened, thereby avoiding the excessive gain variation with temperature, improving the temperature consistency of the amplifier gain, and ensuring that the consistency index of the gain at different temperatures meets the design requirements.

[0016] The circuit of the Ku-band amplifier gain temperature compensation method based on pHEMT process is as follows: Figure 2-3shown.

[0017] pHEMT devices are used for signal amplification, and the amplifier stages are designed according to the amplifier gain index, including at least an input signal amplification stage, an output signal amplification stage, and if necessary, one or more intermediate signal amplification stages.

[0018] Each stage of the amplifier circuit contains a gate DC bias network, a drain DC bias network, and a gate temperature compensation network. The gate DC bias network and the drain DC bias network provide a fixed bias operating voltage, and the gate temperature compensation network provides a variable bias operating voltage that changes with the operating temperature.

[0019] The input end of the circuit is matched to the 50Ω of the previous stage through the impedance matching network and the capacitor is used for DC isolation. The output end is matched to the 50Ω of the next stage through the output matching network and is DC-isolated by capacitors; The output end of the previous stage amplifier device is connected to the input end of the next stage amplifier device through an interstage matching network. The interstage matching network performs impedance matching between the output of the previous stage and the input of the next stage amplifier device, and isolates the drain bias voltage of the previous stage amplifier device from the gate bias voltage of the next stage amplifier device, thereby ensuring that the drain bias voltage of the previous stage and the gate bias voltage of the next stage are isolated; The voltage lead-out node VG of the gate temperature compensation network is connected to the power supply terminal of the gate DC bias network, and the ground terminal of the gate temperature compensation network is grounded.

[0020] The gate temperature compensation network is a resistor divider network with a thermistor, including a thin film resistor R1, a thin film resistor R2, a thermistor RT, a positive DC power supply, a negative DC power supply, and a gate bias voltage lead-out node VG. One branch of VG is composed of a thin film resistor R2 and a negative DC power supply connected in series and then grounded, and the other branch of VG is composed of a table resistor RT, a thin film resistor R1, and a positive DC power supply connected in series and then grounded.

[0021] Technical effects of the present invention: Based on the Ku-band amplifier structure, a gate temperature compensation network is introduced at the gate DC voltage power-on end. The trend of gain change with temperature is optimized through simulation. Through reasonable assignment, different gate input voltages of pHEMT at different temperatures are obtained. In the application frequency band of 14GHz-18GHz, the gain fluctuates less with temperature. The gate temperature compensation network effectively optimizes the amplifier's temperature fluctuation, making the gain index have better high and low temperature consistency.

[0022] The technology of the present invention can be widely applied to various Ku-band power amplifiers. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a schematic diagram of the principle structure of an existing Ku-band amplifier.

[0024] Figure 2 Schematic diagram of the temperature compensation network structure introduced for the gate.

[0025] Figure 3 Schematic diagram of the amplifier structure after the gate temperature compensation network is introduced.

[0026] Figure 4 This is a schematic diagram of the gain fluctuation curve of the existing Ku-band amplifier under high and low temperature conditions.

[0027] Figure 5 Schematic diagram of the amplifier gain fluctuation curve at high and low temperatures after the gate temperature compensation network is introduced.

[0028] Figure 6 This is a schematic diagram of the amplifier layout structure after the gate temperature compensation network is introduced.

[0029] Figure 7 This is a schematic diagram of the gate temperature compensation network layout structure. DETAILED DESCRIPTION

[0030] like Figure 1-7 As shown, taking the Ku-band two-stage power amplifier circuit structure based on pHEMT process as an example, the Ku-band amplifier gain temperature compensation method and circuit thereof are specifically implemented as follows: The operating frequency range of the Ku-band amplifier is 14.0GHz-18.0GHz.

[0031] The gain G of the Ku-band amplifier is G≥19dB at room temperature.

[0032] The thermistor RT is a table resistor.

[0033] The positive DC power supply is +5V.

[0034] The negative DC power supply is -5V.

[0035] The gate bias network input voltage is -5V, and the drain bias network input voltage is 5V.

[0036] The RF signal at the IN port input is a -10dBm PWM continuous wave.

[0037] 1. Existing Ku-band two-stage power amplifier design: Circuit topology such as Figure 1 As shown, the process is implemented using GaAs ED pHEMT 0.25um process, the gate bias network input voltage is -5V, the drain bias network input voltage is 5V, the IN port input signal is a PWM continuous wave of -10dBm, and the gain G≥19dB at room temperature.

[0038] A two-stage pHEMT cascade is used for signal amplification. The gate and drain are powered by independent networks. The RF signal is input from the IN port and output from the OUT port. The signal reaches the input matching network from the input end. Through the input matching network, the amplifier input end is matched to the 50Ω of the previous stage, and the capacitor is isolated. The DC current of the first-stage gate DC signal is isolated from the input end. The output end includes an output matching network, whose function is to match the amplifier output end to the 50Ω of the previous stage and to isolate the DC current of the capacitor. The DC current of the second-stage drain DC signal is isolated from the output end to obtain a good output standing wave. The pHEMT amplifier device in the circuit is the core device, which has the function of signal amplification. In the range of 14GHz-18GHz, the source of the device is connected to the GaAs The through-hole made by 0.25um process is grounded, the gate G is input with gate DC bias signal by external power supply through gate bias network, the first-stage pHEMT amplifier device and the second-stage pHEMT amplifier device are connected through inter-stage matching network, impedance matching is performed between the first-stage output and the second-stage amplifier device input, and the drain bias voltage of the first-stage amplifier device and the gate bias voltage of the second-stage amplifier device are isolated to ensure the first-stage drain bias voltage and the second-stage gate bias voltage. The configuration principle of the gate bias network and drain bias network of the second stage is the same as that of the first stage. An output impedance matching network is added from the second-stage drain end to the output end. The function of the input and output impedance matching network is to match the circuit impedance to the 50 ohm impedance of the input and output ends, and to perform impedance matching with the previous and subsequent chips.

[0039] The initial values ​​of the parameters of each component in the amplifier circuit are obtained by calculation, and the simulation tool is used to optimize the parameters of each component in the circuit. The target is set as the product demand index, and the gain is 19dB. The two-port S parameters of the amplifier can be obtained through the simulation control, and the gain can be obtained. After adjusting the temperature parameters of the device, the gain index at different temperatures can be obtained.

[0040] like Figure 4 As shown in the figure, the amplifier design indicators fluctuate with temperature. The test frequency band is between 14GHz and 18GHz. The amplifier gain is about 19dB at 25℃. When the ambient temperature is -55℃, the amplifier gain increases by 2dB to about 21dB. When the ambient temperature is 125℃, the amplifier gain decreases by 4dB to 15dB. The gain varies between -4dB and +2dB at temperatures between -55℃ and 125℃. Such gain temperature fluctuations are not conducive to the application of stable gain.

[0041] 2. Design of the gate gain temperature compensation network of the present invention: In the design process, the gate bias network using the resistance thermal modulation technology described in the present invention can be introduced. By reasonably assigning values ​​to the table resistors and thin-film resistors in the amplifier bias network and changing the gate voltage at different temperatures, the high and low temperature fluctuations of the amplifier gain can be improved.

[0042] A set temperature-sensitive resistor and a temperature-insensitive resistor are added to the gate bias network to change the gate DC control voltage output by the gate bias network at different temperatures.

[0043] like Figure 2 , Figure 3 As shown, the gate of the amplifier is introduced into the gate bias network using the resistance thermal modulation technology of the present invention, including two temperature-insensitive thin film resistors R1 and R2, and a temperature-sensitive table resistor RT. The layout is as shown in FIG. Figure 6 , Figure 7 As shown. The block resistance of the table resistor at room temperature is 198Ω / □, and its resistance temperature coefficient is +0.3Ω / ℃. The manufacturing process of the temperature-insensitive thin film resistor is GaAs process, and the block resistance of the thin film resistor is 50Ω / □. In this voltage divider network, at room temperature of 25℃, the R1 resistor and the RT resistor are connected in series through a microstrip line. The thin film resistor R1 is 6um wide and 399um long. The table resistor RT is 10um wide and 121um long. The thin film resistor R2 is 6um wide and 516um long.

[0044] The resistance of the thin film resistor R1 is 3.4kΩ, the resistance of the thin film resistor R2 is 4.4kΩ, the resistance of the table resistor RT is 2.2kΩ at 25℃, 1.9kΩ at -55℃, and 2.6kΩ at 125℃. The voltage outputted by the gate DC bias network to the gate of the amplifier device is -0.42V at -55℃, -0.6V at 25℃, and -0.73V at 125℃.

[0045] After introducing the gate bias network of the resistor thermal modulation technology into the amplifier, the gain was tested at high and low temperatures, and the trend obtained was as follows Figure 5 As shown, the gain changes with temperature. At low temperature of -55℃, the gain increases compared with normal temperature. At 125℃, the gain shows a downward trend compared with normal temperature. After the introduction of resistive thermal modulation technology, the gain changes by -1dB to 1dB in the range of -55℃ to 125℃, which is improved compared with the change between -4dB and +2dB.

[0046] The circuit operation mechanism is as follows: The definition of the gain temperature consistency is to use simulation software to simulate the temperature characteristics of the Ku-band amplifier, and to simulate and calculate the gain of the circuit at -55°C, 125°C, and 25°C, respectively, to evaluate the difference between the gain at -55°C and 125°C and the gain at 25°C, and to determine the value of the Ku-band amplifier gain at different temperatures.

[0047] By adjusting the values ​​of resistors R1, R2, and RT, the voltage value input to the gate terminal of the amplifier by the gate bias network is different at different temperatures. The voltage output to the gate of the amplifier device by the gate DC bias network is -0.42V at -55℃, -0.6V at 25℃, and -0.73V at 125℃. Through simulation verification, the trend of the amplifier's own gain fluctuating with temperature between -55℃ and 125℃ is bridged, and the consistency of the amplifier's gain at different temperatures is improved.

[0048] In summary, based on the pHEMT amplifier device, a GaAs power amplifier with a two-stage amplification structure is constructed. According to the fluctuation of the gain of the pHEMT amplifier with temperature, the resistance value of the temperature compensation resistor in the gate bias network is determined, and the gate bias voltage is divided by the gate temperature compensation resistor. Since the resistance value of the table resistor changes with temperature, the DC voltage output by the gate bias network will change accordingly with temperature, thereby controlling the change in gain.

[0049] When the working environment temperature changes, the fluctuation of the amplifier gain with temperature in the target frequency band of 14.0GHz-18.0GHz is weakened, thereby avoiding the excessive tolerance of the gain due to drastic changes with temperature, improving the temperature consistency of the amplifier gain, and making the consistency index of the gain at different temperatures meet the design requirements.

[0050] Finally, it should be noted that the above embodiments are merely examples for the purpose of clear explanation. The present invention includes but is not limited to the above embodiments. It is not necessary and impossible to list all implementation methods exhaustively. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. All implementation methods that meet the requirements of the present invention belong to the protection scope of the present invention.

Claims

1. A Ku-band amplifier gain temperature compensation method, characterized in that: The method is: (1) Based on pHEMT amplifier devices, a GaAs power amplifier with two or more amplification structures is formed; (2) A gate temperature compensation bias network with resistor thermal modulation technology is introduced into the gate of the pHEMT amplifier, and resistor thermal modulation technology is used to monitor the amplifier gain fluctuation with temperature; (3) The initial values ​​of the parameters of each component in the pHEMT amplifier circuit are obtained by calculation, and the parameters of each device in the circuit are optimized according to the product demand indicators using simulation tools. The two-port S parameters of the amplifier can be obtained through simulation controls. After adjusting the device temperature parameters, the gain at different temperatures is obtained. According to the fluctuation of the gain with temperature, the gate bias network is built and the resistance value of the temperature compensation resistor is determined; (4) The gate bias voltage is divided by the gate temperature compensation resistor. When the ambient temperature changes, the temperature fluctuation of the amplifier gain in the target frequency band of 14.0 GHz-18.0 GHz is weakened, thereby avoiding the excessive gain variation with temperature, improving the temperature consistency of the amplifier gain, and ensuring that the consistency index of the gain at different temperatures meets the design requirements.

2. The circuit of a Ku-band amplifier gain temperature compensation method according to claim 1, characterized in that: The circuit adopts pHEMT device to amplify the signal, and designs the amplifier amplification stage according to the amplifier gain index, including at least input signal amplification stage, output signal amplification stage, and one or more intermediate signal amplification stages when necessary; Each stage of the amplifier circuit contains a gate DC bias network, a drain DC bias network, and a gate temperature compensation network. The gate DC bias network and the drain DC bias network provide a fixed bias operating voltage, and the gate temperature compensation network provides a variable bias operating voltage that changes with the operating temperature. The input end of the circuit is matched to the 50Ω of the previous stage through the impedance matching network and the capacitor is used for DC isolation. The output end is matched to the 50Ω of the next stage through the output matching network and is DC-isolated by capacitors; The output end of the previous stage amplifier device is connected to the input end of the next stage amplifier device through an interstage matching network. The interstage matching network performs impedance matching between the output of the previous stage and the input of the next stage amplifier device, and isolates the drain bias voltage of the previous stage amplifier device from the gate bias voltage of the next stage amplifier device, thereby ensuring that the drain bias voltage of the previous stage and the gate bias voltage of the next stage are isolated; The voltage lead-out node VG of the gate temperature compensation network is connected to the power supply terminal of the gate DC bias network, and the ground terminal of the gate temperature compensation network is grounded.

3. The circuit of a Ku-band amplifier gain temperature compensation method as claimed in claim 2, characterized in that: The gate temperature compensation network is a resistor divider network with a thermistor, including a thin film resistor R1, a thin film resistor R2, a thermistor RT, a positive DC power supply, a negative DC power supply, and a gate bias voltage lead-out node VG. One branch of VG is composed of a thin film resistor R2 and a negative DC power supply connected in series and then grounded, and the other branch of VG is composed of a thermistor RT, a thin film resistor R1, and a positive DC power supply connected in series and then grounded.

4. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 3, characterized in that: The thermistor is a table resistor, and the table resistor RT has a width of 10 um and a length of 121 um.

5. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 4, characterized in that: The table resistor RT has a resistance value of 2.2 kΩ at 25° C., a resistance value of 1.9 kΩ at -55° C., and a resistance value of 2.6 kΩ at 125° C.

6. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 3, characterized in that: The thin film resistor is a metal thin film resistor, and the manufacturing process is GaAs ED pHEMT 0.25um process.

7. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 3, characterized in that: The block resistance of the thin film resistor is 50Ω / □, the thin film resistor R1 has a width of 6um and a length of 399um, and the thin film resistor R2 has a width of 6um and a length of 516um.

8. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 7, characterized in that: The resistance value of the thin film resistor R1 is 3.4 kΩ, and the resistance value of the thin film resistor R2 is 4.4 kΩ.

9. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 3, characterized in that: The R1 and RT are connected in series via a microstrip line.

10. The circuit of the Ku-band amplifier gain temperature compensation method according to claim 3, characterized in that: The manufacturing process of the pHEMT is GaAs ED pHEMT 0.25um process; the voltage outputted from the gate DC bias network to the gate of the amplifier device is -0.42V at -55°C, -0.6V at 25°C, and -0.73V at 125°C.

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