Gain control circuit and communication device

Abstract

The invention discloses a gain control circuit and communication equipment, relates to the technical field of power electronics, and discloses the gain control circuit which comprises a driving module, an adjusting module and a variable gain amplifier module. The driving module is connected with the adjusting module; and the adjusting module is also connected with the variable gain amplifier module. Transmitting a driving signal which is not influenced by the temperature change to an adjusting module through a driving module based on a target demand; the adjusting module adjusts the control voltage of the variable gain amplifier module according to the driving signal; the adjusting module feeds back a feedback voltage corresponding to the driving signal to the variable gain amplifier module based on the control voltage, and finally the variable gain amplifier module adjusts the output gain based on the feedback voltage and the control voltage. The gain of the variable gain amplifier module is controlled by the driving signal and does not change along with the temperature through the feedback voltage limiting distribution relation.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a gain control circuit and a communication device. Background Art

[0002] Variable gain amplifiers have been used in a variety of remote sensing and communications equipment for more than half a century. Early designs achieved gain selection by switching fixed gain amplifier stages, which often adjusted receiver sensitivity in a binary manner. As semiconductor technology continued to advance, VGA designs gradually shifted from using step attenuators and fixed gain amplifiers to achieving a wider range of discrete gain control. Modern designs achieve continuous voltage-controlled gain using advanced techniques such as voltage variable attenuators, multipliers, and gain interpolators.

[0003] Although the existing variable gain amplifier circuit has the advantages of wide dynamic range and automatic gain control, it can realize signal processing with wide dynamic range and adapt to different input signal levels, thereby improving the sensitivity and accuracy of the system. The gain can be automatically adjusted to maintain the constant power of the output signal, thereby avoiding saturation or under-driving of the amplifier or analog-to-digital converter (ADC). However, there are still factors such as temperature, voltage, and process that lead to instability and inconsistency of the output signal, that is, the gain is greatly affected by temperature changes. Summary of the invention

[0004] The main purpose of the present application is to provide a gain control circuit and a communication device, aiming to solve the technical problem that the output gain of the existing variable gain amplifier circuit is greatly affected by temperature.

[0005] To achieve the above-mentioned purpose, the present application proposes a gain control circuit, which includes: a driving module, an adjustment module and a variable gain amplifier module; the driving module is connected to the adjustment module; the adjustment module is also connected to the variable gain amplifier module; the driving module is used to transmit a driving signal to the adjustment module; the adjustment module is used to adjust the control voltage of the variable gain amplifier module according to the driving signal; the adjustment module is also used to feed back a feedback voltage corresponding to the driving signal to the variable gain amplifier module based on the control voltage, and the variable gain amplifier module is used to adjust the gain based on the feedback voltage and the control voltage.

[0006] In one embodiment, the variable gain amplifier module includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode, a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a first current source, a second current source and an RC network; the first end of the first resistor, the first end of the second resistor, the first end of the third resistor and the first end of the fourth resistor are all connected to a working power supply; the second end of the first resistor, the second end of the second resistor, the second end of the third resistor and the second end of the fourth resistor are respectively connected to the collector of the first triode, the collector of the second triode, the collector of the third triode, the collector of the fourth triode the collector of the second transistor; the base of the second transistor is connected to the base of the third transistor; the base of the first transistor is connected to the base of the fourth transistor; the emitter of the first transistor is connected to the emitter of the second transistor and the collector of the fifth transistor; the emitter of the third transistor is connected to the emitter of the fourth transistor and the collector of the sixth transistor; the emitter of the fifth transistor is connected to the emitter of the sixth transistor through the RC network; the emitter of the fifth transistor is also grounded through the first current source; the emitter of the sixth transistor is also grounded through the second current source; the RC network is used to compensate for the gain of the variable gain amplifier module.

[0007] In one embodiment, the driving module includes: a reference current source and a first reference resistor; the first end of the first reference resistor is connected to a working power supply; the second end of the first reference resistor is connected to the first input end of the adjustment module and the first end of the reference current source; the second end of the reference current source is grounded.

[0008] In one embodiment, the adjustment module includes: an operational amplifier; a first input terminal of the operational amplifier, connected to the second end of the first reference resistor; a second input terminal of the operational amplifier, connected to the second end of the second resistor and the second end of the third resistor; and an output terminal of the operational amplifier, connected to the base of the second transistor.

[0009] In one embodiment, the variable gain amplifier module includes: a first resistor, a first MOS tube, a fourth resistor, a first triode, a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a first current source, a second current source and an RC network; the first end of the first resistor, the source of the first MOS tube and the first end of the fourth resistor are all connected to a working power supply; the gate of the first MOS tube is connected to the drain of the first MOS tube; the second end of the first resistor and the second end of the fourth resistor are respectively connected to the collector of the first triode and the collector of the fourth triode; the drain of the first MOS tube is respectively connected to the collector of the second triode and the collector of the first The collector of the third transistor; the base of the second transistor is connected to the base of the third transistor; the base of the first transistor is connected to the base of the fourth transistor; the emitter of the first transistor is connected to the emitter of the second transistor and the collector of the fifth transistor; the emitter of the third transistor is connected to the emitter of the fourth transistor and the collector of the sixth transistor; the emitter of the fifth transistor is connected to the emitter of the sixth transistor through the RC network; the emitter of the fifth transistor is also grounded through the first current source; the emitter of the sixth transistor is also grounded through the second current source; the RC network is used to compensate for the gain of the variable gain amplifier module.

[0010] In one embodiment, the driving module includes: a reference current source and a first reference resistor; the first end and the second end of the reference current source are respectively connected to a working power supply and the first end of the first reference resistor; the first end of the first reference resistor is also connected to the first input end of the adjustment module; the second end of the first reference resistor is grounded.

[0011] In one embodiment, the adjustment module includes: an operational amplifier, a second MOS tube and a second reference resistor; the source and drain of the second MOS tube are respectively connected to a working power supply and a first end of the second reference resistor; the gate of the second MOS tube is connected to the drain of the first MOS tube; the first end of the second reference resistor is also connected to the second input end of the operational amplifier; and the second end of the second reference resistor is grounded.

[0012] In one embodiment, the first resistor and the fourth resistor have the same parameters, the first transistor and the fourth transistor have the same parameters, the second transistor and the third transistor have the same parameters, and the first current source and the second current source have the same parameters.

[0013] In one embodiment, the RC network includes: a fifth resistor and a first capacitor; the first end of the fifth resistor is connected to the emitter of the fifth transistor and the first end of the first capacitor; the second end of the fifth resistor is connected to the emitter of the sixth transistor and the second end of the first capacitor.

[0014] In addition, to achieve the above-mentioned purpose, the present application also proposes a communication device, which applies the gain control circuit as described above.

[0015] One or more technical solutions proposed in this application have at least the following technical effects:

[0016] The driving module transmits a driving signal that is not affected by temperature changes to the adjustment module based on target requirements; the adjustment module adjusts the control voltage of the variable gain amplifier module according to the driving signal; the adjustment module then feeds back a feedback voltage corresponding to the driving signal to the variable gain amplifier module based on the control voltage, and finally the variable gain amplifier module adjusts the output gain based on the feedback voltage and the control voltage, and the feedback voltage limiting distribution relationship is used to achieve that the gain of the variable gain amplifier module is controlled by the driving signal and does not change with temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 A circuit diagram of an existing variable gain amplifier;

[0020] Figure 2 A structural block diagram provided for an embodiment of a gain control circuit of the present application;

[0021] Figure 3 A circuit diagram of an implementation method provided for a gain control circuit embodiment of the present application;

[0022] Figure 4 Another circuit connection diagram of an implementation method provided for the gain control circuit embodiment of the present application;

[0023] Figure 5 A circuit diagram of another implementation of the gain control circuit embodiment of the present application;

[0024] Figure 6 Another circuit connection diagram of another implementation manner provided for the gain control circuit embodiment of the present application.

[0025] Description of Figure Numbers:

[0026] Label illustrate Label illustrate 10 Driver module R1 to R4 The first to fourth resistors 20 Adjustment module T1 to T6 The first to sixth transistors 30 Variable Gain Amplifier Module Isource1 The first current source IREF Reference current source Isource2 The second current source R5 / R6 The first and second reference resistors RC circuit RC Network AMP Operational Amplifier M1 / M2 First and second MOS tubes

[0027] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0029] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0030] Although the existing variable gain amplifier circuit has the advantages of wide dynamic range and automatic gain control, it can realize signal processing with wide dynamic range and adapt to different input signal levels, thereby improving the sensitivity and accuracy of the system. The gain can be automatically adjusted to maintain the constant power of the output signal, thereby avoiding saturation or under-driving of the amplifier or analog-to-digital converter (ADC). However, there are still factors such as temperature, voltage, and process that lead to instability and inconsistency of the output signal, that is, the gain is greatly affected by temperature changes.

[0031] Please refer to Figure 1 , Figure 1 The circuit structure diagram of an existing variable gain amplifier is shown in FIG.

[0032] It should be noted that Figure 1 The working principle of the variable gain amplifier circuit shown is that by adjusting the bias voltage, that is, the voltage difference between the base voltages VBias1 and VBias2 of the transistors, the DC current flowing through the first transistor T1, the second transistor T2, the third transistor T3, and the fourth transistor T4 can be controlled. This current distribution relationship further determines the distribution of the AC gain current. It can be understood that since the distribution of the AC gain current is consistent with the DC current, the gain of the VGA can be adjusted by changing the DC current.

[0033] It should be noted that when the temperature changes, even if the voltage difference between VBias1 and VBias2 remains unchanged, the DC current distribution relationship between T1 and T2, T4 and T3 will change. This is due to the characteristic that the base-emitter voltage (VBE) of the transistor changes with temperature.

[0034] Similarly, due to the change in the DC current distribution relationship, the AC gain current distribution relationship between the first transistor T1 and the second transistor T2, the third transistor T3 and the fourth transistor T4 will also change, resulting in a change in the gain of the VGA.

[0035] Specifically, the formula IC = IS*exp(VBE*q / kT) describes the relationship between the transistor collector current IC and the temperature T and the base-emitter voltage VBE. Among them, IS is the saturation current, which is related to the specific process and size of the transistor, q is the electron charge, and k is the Boltzmann constant. Because IC T1 +IC T2 =Isource1,IC T1 / IC T2 =(IS*exp(VBE T1 *q / kT)) / (IS*exp(VBE T2 *q / kT))=exp((VBE T1 -VBE T2 )*q / kT).

[0036] It can be seen from this formula that as the temperature T changes, even if the voltage difference between VBias1 and VBias2 remains unchanged, the current distribution relationship between gains T1 and T2 will change due to temperature changes; similarly, T4 and T3 also change.

[0037] In order to reduce the impact of temperature changes on VGA gain, a circuit that can automatically compensate for temperature changes is usually designed to keep the VGA gain stable. This usually involves using a thermal element (such as a thermistor or thermocouple) to monitor temperature changes and adjust the voltage difference between VBias1 and VBias2 accordingly. However, the temperature compensation circuit has the problem of under-compensation or over-compensation and increases power consumption and cost. At the same time, the instability of the thermal element is also a considerable problem.

[0038] Based on this, the embodiment of the present application provides a gain control circuit, which optimizes the circuit structure by adding a driving module and an adjustment module to achieve gain that does not change with temperature. Figure 2 , Figure 2 A structural block diagram of a gain control circuit embodiment of the present application.

[0039] In this embodiment, the gain control circuit comprises: a driving module 10, an adjusting module 20 and a variable gain amplifier module 30. The driving module 10 is connected to the adjusting module 20; the adjusting module 20 is also connected to the variable gain amplifier module.

[0040] It should be noted that the driving module 10 is responsible for providing stable driving signals or voltages, and these signals or voltages are used to control the working states of the regulating module 20 and the variable gain amplifier module 30 .

[0041] It should be noted that the adjustment module 20 receives signals from the driving module 10 and generates instructions capable of adjusting the gain of the variable gain amplifier module 30 according to these signals. The specific instruction form is determined according to the selection.

[0042] It should be noted that the design of the adjustment module 20 may select a temperature compensation circuit or other adjustment mechanism to ensure that the gain does not change with temperature. These mechanisms can monitor temperature changes in real time and adjust circuit parameters accordingly to offset the effect of temperature changes on the gain. For example, an operational amplifier may be selected to output the control voltage and the feedback voltage through the operational amplifier.

[0043] It should be noted that the variable gain amplifier module 30 is the core part of the circuit, which is responsible for amplifying the input signal. Its gain can be adjusted according to the instructions of the adjustment module 20. By changing the gain of the variable gain amplifier module 30, the output signal amplitude can be accurately controlled.

[0044] It can be understood that the driving module 10 is used to transmit the driving signal to the adjusting module 20; the adjusting module 20 is used to adjust the control voltage of the variable gain amplifier module 30 according to the driving signal; the adjusting module is also used to feedback a feedback voltage corresponding to the driving signal to the variable gain amplifier module based on the control voltage, and the variable gain amplifier module is used to adjust the gain based on the feedback voltage and the control voltage.

[0045] It should be noted that the driving signal may include specific instructions or parameters for gain adjustment, and have clear characteristics such as level, frequency, waveform or current, so as to ensure that the adjustment module can accurately interpret and perform corresponding gain adjustment operations.

[0046] It should be noted that the adjustment module 20 receives the driving signals from the driving module 10 and adjusts the control voltage of the variable gain amplifier module 30 according to these signals. The control voltage is the bias voltage in the variable gain amplifier module 30 that changes the transistor characteristics.

[0047] It is understandable that the control voltage regulation module will also output a feedback voltage corresponding to the drive signal. This feedback voltage is used to further accurately control the output gain of the variable gain amplifier module 30, limit the voltage of the non-output triode branch in its symmetrical unit to the feedback voltage, and then make the current of the non-output triode branch constant in association with the feedback voltage. At this time, although the control voltage changes with temperature, the current distribution relationship is limited by the feedback voltage and does not change with temperature.

[0048] In this embodiment, a driving signal that is not affected by temperature changes is transmitted to the adjustment module through the driving module based on target requirements; the adjustment module adjusts the control voltage of the variable gain amplifier module according to the driving signal; the adjustment module then feeds back a feedback voltage corresponding to the driving signal to the variable gain amplifier module based on the control voltage, and finally the variable gain amplifier module adjusts the output gain based on the feedback voltage and the control voltage, and the feedback voltage limiting distribution relationship is used to achieve the gain of the variable gain amplifier module being controlled by the driving signal without changing with temperature.

[0049] Based on the above content, this embodiment provides a feasible implementation method. Figure 3 A circuit diagram of an implementation scheme provided for a gain control circuit embodiment of the present application.

[0050] The variable gain amplifier module includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5, a sixth transistor T6, a first current source Isource1, a second current source Isource2 and an RC network.

[0051] It should be noted that the first end of the first resistor R1, the first end of the second resistor R2, the first end of the third resistor R3 and the first end of the fourth resistor R4 are all connected to the working power supply; the second end of the first resistor R1, the second end of the second resistor R2, the second end of the third resistor R3 and the second end of the fourth resistor R4 are respectively connected to the collector of the first triode T1, the collector of the second triode T2, the collector of the third triode T3 and the collector of the fourth triode T4; the base of the second triode T2 is connected to the base of the third triode T3; the first triode The base of the first transistor T1 is connected to the base of the fourth transistor; the emitter of the first transistor T1 is connected to the emitter of the second transistor T2 and the collector of the fifth transistor T5; the emitter of the third transistor T3 is connected to the emitter of the fourth transistor T4 and the collector of the sixth transistor T6; the emitter of the fifth transistor T5 is connected to the emitter of the sixth transistor T6 through the RC network; the emitter of the fifth transistor T5 is also grounded through the first current source Isource1; the emitter of the sixth transistor T6 is also grounded through the second current source Isource2.

[0052] It should be noted that the first ends of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 are all connected to the working power supply to provide the necessary DC voltage for the circuit. The second ends of these resistors are respectively connected to the collectors of the first triode T1, the second triode T2, the third triode T3 and the fourth triode T4. This connection method provides the necessary bias voltage for the triodes and allows them to work in different gain states.

[0053] It should be noted that the bases of the second transistor T2 and the third transistor T3 are connected to each other to achieve a voltage-following connection control voltage Vbias1 , thereby enhancing the stability of the circuit or achieving a specific gain characteristic.

[0054] It should be noted that the emitter of the first transistor T1 is connected to the emitter of the second transistor T2 and the collector of the fifth transistor T5 to form an amplifier structure. Similarly, the emitter of the third transistor T3 is connected to the emitter of the fourth transistor T4 and the collector of the sixth transistor T6 to form an amplifier structure.

[0055] It should be noted that the emitter of the fifth transistor T5 is connected to the emitter of the sixth transistor T6 via an RC network (which may include a resistor and a capacitor). This network is used to achieve functions such as frequency compensation, phase adjustment or gain conversion.

[0056] Specifically, this embodiment provides a feasible RC network, which includes: a fifth resistor and a first capacitor; the first end of the fifth resistor is connected to the emitter of the fifth transistor and the first end of the first capacitor; the second end of the fifth resistor is connected to the emitter of the sixth transistor and the second end of the first capacitor.

[0057] It should be noted that the fifth resistor and the first capacitor can be adjusted by normal switches, or adjustable devices can be selected. The performance of the circuit can be optimized by adjusting the resistance of the fifth resistor and the capacitance of the first capacitor. For example, by changing the resistance of the fifth resistor, the degree of gain conversion can be adjusted, thereby changing the gain and stability of the amplifier. Similarly, by changing the capacitance of the first capacitor, the size and position of the frequency compensation can be adjusted to meet different application requirements.

[0058] It should be noted that the first current source Isource1 and the second current source Isource2 provide a stable direct current for the circuit, which helps to achieve more accurate gain control.

[0059] The driving module 10 includes: a reference current source IREF and a first reference resistor R5; the first end of the first reference resistor R5 is connected to a working power supply; the second end of the first reference resistor R5 is connected to the first input end of the regulating module 20 and the first end of the reference current source IREF; the second end of the reference current source is grounded.

[0060] It should be noted that the reference current source IREF is a stable DC current source, which can be used to provide an accurate reference current for the circuit. The second terminal of the reference current source is grounded to ensure that its current output is stable and free from external interference.

[0061] It should be noted that the first reference resistor R5 is used to convert the current provided by the reference current source IREF into a voltage. The first end of the first reference resistor R5 is connected to the working power supply to provide it with the necessary DC voltage. The second end is connected to the first input end of the adjustment module 20 and the first end of the reference current source IREF to form a current-voltage conversion circuit.

[0062] It should be noted that, in addition to adjusting the reference current source IREF, the value of the first reference resistor R5 may also be adjusted, so that the voltage output to the first input terminal of the adjustment module 20 can also be adjusted.

[0063] It is understandable that when the reference current source IREF provides a stable current, the current will generate a voltage drop through the first reference resistor R5. This voltage drop (i.e., the voltage across R5) is proportional to the reference current IREF and the resistance value of the resistor R5, and can be expressed as V=IREF*R5. Therefore, by selecting a suitable resistor R5 and reference current IREF, an accurate reference voltage can be generated as a driving signal to be sent to the first input terminal of the adjustment module 20.

[0064] The adjustment module 20 includes: an operational amplifier AMP; a first input end of the operational amplifier AMP, connected to the second end of the first reference resistor R5; a second input end of the operational amplifier AMP, connected to the second end of the second resistor R2 and the second end of the third resistor R3; and an output end of the operational amplifier AMP, connected to the base of the second transistor T3.

[0065] It should be noted that the operational amplifier AMP is a core component of the regulation module 20, which is used to implement the regulation function. It has two input terminals (usually marked as "+" and "-" or "inverting" and "non-inverting") and an output terminal.

[0066] In this embodiment, the first input terminal of the operational amplifier AMP is an inverting input terminal connected to the second terminal of the first reference resistor R5 to receive the driving signal from the driving module 10 .

[0067] It should be noted that the second input terminal (opposite to the first input terminal) is connected to the second ends of the second resistor R2 and the third resistor R3 (i.e., connected to the nodes of the collectors of the second transistor T2 and the third transistor T3), and these nodes represent a certain feedback voltage or a voltage after voltage division of the variable gain amplifier module 30. The output terminal of the operational amplifier AMP is connected to the base of the second transistor T2 and the base of the third transistor T3, and this output signal is used to control the conduction state of the transistors, thereby adjusting the gain of the variable gain amplifier module 30.

[0068] Specifically, according to symmetry, the first resistor R1 and the fourth resistor R4 have the same parameters, the second resistor R2 and the third resistor R3 have the same parameters (the second resistor and the third resistor may also be combined into one resistor), the first transistor T3 and the fourth transistor T4 have the same parameters, the second transistor T2 and the third transistor T3 have the same parameters, and the first current source and the second current source have the same parameters.

[0069] In this structure, the base voltage VBias2 of the first transistor T1 and the fourth transistor T4 can be a constant value or a variable value, and the voltage value of the control voltage selection VBias1 is obtained through the output of the operational amplifier AMP. During normal operation, we set the reference current source IREF value, then the drive signal VREF=VDD-IREF*R5, at this time, the operational amplifier AMP will automatically adjust the value of the control voltage VBias1, so that the feedback voltage VFB=VDD-IR2*R2=VREF (IR2=IR3, R2=R3, IR2 is the current flowing through the resistor R2).

[0070] It is understandable that if Figure 4 As shown, VBias2 can also be selected as the control voltage obtained through the amplifier output. In this case, the base voltage VBias1 of the second transistor T2 and the third transistor T3 can be a constant value or a variable value. In this case, the first input terminal of the operational amplifier AMP is the in-phase input terminal.

[0071] It can be understood that the operational amplifier AMP has two input terminals, the first input terminal receives the drive signal VREF, and the second input terminal receives the feedback voltage VFB. There is a comparator inside the amplifier to compare the voltage values ​​of VREF and VFB. When the reference signal VREF and VFB are not equal, the comparator will output an error signal. This error signal will be used to adjust the value of VBias1, thereby changing the working state of the circuit so that the feedback voltage VFB gradually approaches the drive signal VREF. Through a closed-loop feedback system, the amplifier can continuously monitor the voltages of the drive signal VREF and the feedback voltage VFB, and adjust VBias1 as needed.

[0072] At this time, the current IR2 flowing through the second resistor R2 = IREF*R5 / R2 = IREF*M (assuming that the first reference resistor R5 is M times the second resistor R2), and the current flowing through the second transistor T2 is equal to the current IR2 flowing through the second resistor R2, so the current IT2 flowing through the second transistor T2 = IREF*M, by adjusting the value of the different reference current sources IREF, the current value of the current IT2 flowing through the second transistor T2 is adjusted, thereby adjusting the gain. Moreover, since the reference current source IREF does not change with temperature, IT2 does not change with temperature.

[0073] Based on the above content, it can be known that when the gain ΔI is generated in the variable gain amplifier module loop, the gain ΔI is determined by the device parameters and does not change with temperature. Since the output of the first current source Isource1 is constant, the current of the left structure is Isource1+ΔI, and the current IT1 flowing through the first transistor all Isource1*(IT1 / Isource1)+ΔI*(IT1 / Isource1), IT1 / Isource1=(Isource1-IT2) / Isource1 does not change with temperature, and a new distribution relationship that does not change with temperature is established, that is, the circuit gain (R1*ΔI*IT1 / Isource1) is achieved without changing with temperature.

[0074] This embodiment also provides another feasible implementation method, please refer to Figure 5 , Figure 5 A circuit diagram of another implementation scheme provided for the gain control circuit embodiment of the present application.

[0075] The variable gain amplifier module 30 includes: a first resistor R1, a first MOS transistor M1, a fourth resistor R4, a first transistor T1, a second transistor T2, a third transistor T3, a fourth transistor T4, a fifth transistor T5, a sixth transistor T6, a first current source Isource1, a second current source Isource2 and an RC network.

[0076] Wherein, the first end of the first resistor R1, the source of the first MOS transistor M1 and the first end of the fourth resistor R4 are all connected to the working power supply; the gate of the first MOS transistor M1 is connected to the drain of the first MOS transistor M1; the second end of the first resistor R1 and the second end of the fourth resistor R4 are respectively connected to the collector of the first triode T1 and the collector of the fourth triode T4; the drain of the first MOS transistor M1 is respectively connected to the collector of the second triode T2 and the collector of the third triode T3; the base of the second triode T2 is connected to the base of the third triode T3; the first The base of the transistor is connected to the base of the fourth transistor; the emitter of the first transistor T1 is connected to the emitter of the second transistor T2 and the collector of the fifth transistor T5; the emitter of the third transistor T3 is connected to the emitter of the fourth transistor T4 and the collector of the sixth transistor T6; the emitter of the fifth transistor T5 is connected to the emitter of the sixth transistor T6 through the RC network; the emitter of the fifth transistor T5 is also grounded through the first current source Isource1; the emitter of the sixth transistor T6 is also grounded through the second current source Isource2.

[0077] It should be noted that in this embodiment, the second resistor R2 and the third resistor R3 are replaced by a first MOS tube, whose gate and drain are connected to form a diode connection to stabilize the voltage and monitor the current of the second transistor T2 and the third transistor T3. Similarly, the RC network can select the structure described above.

[0078] The driving module 10 includes: a reference current source IREF and a first reference resistor R5; the first end and the second end of the reference current source IREF are respectively connected to a working power supply and the first end of the first reference resistor R5; the first end of the first reference resistor R5 is also connected to the first input end of the adjustment module 20; the second end of the first reference resistor R5 is grounded.

[0079] It is understandable that, through this connection, the driving module 10 can provide a stable driving signal VREF for the regulating module 20. The voltage or current is determined by the reference current source IREF and the first reference resistor R5, specifically depending on the current value of IREF and the resistance value of R5.

[0080] The regulating module 20 includes: an operational amplifier AMP, a second MOS tube M2 and a second reference resistor R6; the source and drain of the second MOS tube M2 are respectively connected to a working power supply and a first end of the second reference resistor R2; the gate of the second MOS tube M2 is connected to the drain of the first MOS tube M1; the first end of the second reference resistor R6 is also connected to the second input end of the operational amplifier AMP; the second end of the second reference resistor R6 is grounded.

[0081] It is understandable that the source of the second MOS tube M2 is connected to the working power supply, and the drain is connected to the first end of the second reference resistor R6. This configuration usually means that M2 acts as a current mirror to proportionally copy the current of M1, and after flowing through the resistor R6, a feedback voltage is generated to the second input end of the operational amplifier AMP.

[0082] It can be understood that the first end of the second reference resistor R6 is connected to the drain of the second MOS tube M2 and the second input end of the AMP, usually the inverting input end, and the second end is grounded. R6 here plays the role of monitoring the current of M2, and together with the drain current of M2 determines the voltage of the inverting input end of the AMP.

[0083] Specifically, the first resistor and the fourth resistor have the same parameters, the first transistor and the fourth transistor have the same parameters, the second transistor and the third transistor have the same parameters, and the first current source and the second current source have the same parameters. Assume that the resistance of the first reference resistor R5 is A times that of the second reference resistor R6, and the size of the first MOS tube M1 is B times that of the second MOS tube M2.

[0084] At this time, the bias voltage VBias2 can be a constant value or a variable value, and the voltage value of the control voltage VBias1 is obtained by the amplifier output. Figure 6 As shown, VBias2 can also be selected as the control voltage obtained through the amplifier output. In this case, the base voltage VBias1 of the second transistor T2 and the third transistor T3 can be a constant value or a variable value. In this case, the first input terminal of the operational amplifier AMP is the inverting input terminal.

[0085] When working normally, we set IREF, then the drive signal VREF=IREF*R5, the amplifier will automatically adjust the value of the control voltage VBias1, so that the feedback voltage VFB=IR6*R6=VREF, IR6 is the current flowing through the sixth resistor R6, then IR6=IM2=IM1 / B, and the sum of the current flowing through the second transistor T2 and the third transistor T3 is equal to IM1, so the current flowing through the second transistor T2 IT2=IM1 / 2=IM2*B / 2=IR6*B / 2=IREF*A*B / 2. Thus, by adjusting different IREF values, the current value of IT2 is adjusted, thereby adjusting the gain. Moreover, IREF does not change with temperature, so IT2 does not change with temperature.

[0086] Based on the above content, it can be known that when the gain ΔI is generated in the variable gain amplifier module loop, the gain ΔI is determined by the device parameters and does not change with temperature. Since the output of the first current source Isource1 is constant, the current of the left structure is Isource1+ΔI, and the current IT1 flowing through the first transistor all Isource1*(IT1 / Isource1)+ΔI*(IT1 / Isource1), IT1 / Isource1=(Isource1-IT2) / Isource1 does not change with temperature, and a new distribution relationship that does not change with temperature is established, that is, the circuit gain (R1*ΔI*IT1 / Isource1) is achieved without changing with temperature.

[0087] The communication device provided by the present application adopts the gain control circuit in the above embodiment, which can solve the technical problem that the output gain of the existing variable gain amplifier circuit is greatly affected by temperature. Compared with the prior art, the beneficial effects of the communication device provided by the present application are the same as the beneficial effects of the gain control circuit provided by the above embodiment, and other technical features in the communication device are the same as the features disclosed in the above embodiment method, which will not be repeated here.

[0088] The above descriptions are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect applications in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A gain control circuit, characterized in that: The gain control circuit comprises: a driving module, an adjusting module and a variable gain amplifier module; The driving module is connected to the regulating module; The adjustment module is also connected to the variable gain amplifier module; The driving module is used to transmit a driving signal to the regulating module; The regulating module is used to regulate the control voltage of the variable gain amplifier module according to the driving signal; The regulating module is further configured to feed back a feedback voltage corresponding to the driving signal to the variable gain amplifier module based on a control voltage. The variable gain amplifier module is used to adjust the gain based on the feedback voltage and the control voltage.

2. The gain control circuit according to claim 1, characterized in that: The variable gain amplifier module includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode, a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a first current source, a second current source and an RC network; The first end of the first resistor, the first end of the second resistor, the first end of the third resistor and the first end of the fourth resistor are all connected to a working power supply; The second end of the first resistor, the second end of the second resistor, the second end of the third resistor and the second end of the fourth resistor are connected to the collector of the first triode, the collector of the second triode, the collector of the third triode and the collector of the fourth triode respectively; The base of the second triode is connected to the base of the third triode; The base of the first transistor is connected to the base of the fourth transistor; The emitter of the first triode is connected to the emitter of the second triode and the collector of the fifth triode; The emitter of the third triode is connected to the emitter of the fourth triode and the collector of the sixth triode; The emitter of the fifth transistor is connected to the emitter of the sixth transistor through the RC network; The emitter of the fifth triode is also grounded through the first current source; The emitter of the sixth triode is also grounded through the second current source; The RC network is used to compensate for the gain of the variable gain amplifier module.

3. The gain control circuit according to claim 2, characterized in that: The driving module comprises: a reference current source and a first reference resistor; The first end of the first reference resistor is connected to a working power supply; The second end of the first reference resistor is connected to the first input end of the adjustment module and the first end of the reference current source; A second terminal of the reference current source is grounded.

4. The gain control circuit according to claim 3, characterized in that: The regulating module comprises: an operational amplifier; The first input terminal of the operational amplifier is connected to the second terminal of the first reference resistor; The second input terminal of the operational amplifier is connected to the second end of the second resistor and the second end of the third resistor; The output end of the operational amplifier is connected to the base of the second transistor.

5. The gain control circuit according to claim 1, wherein: The variable gain amplifier module includes: a first resistor, a first MOS transistor, a fourth resistor, a first triode, a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a first current source, a second current source and an RC network; The first end of the first resistor, the source of the first MOS tube and the first end of the fourth resistor are all connected to a working power supply; The gate of the first MOS tube is connected to the drain of the first MOS tube; The second end of the first resistor and the second end of the fourth resistor are connected to the collector of the first transistor and the collector of the fourth transistor respectively; The drain of the first MOS tube is connected to the collector of the second transistor and the collector of the third transistor respectively; The base of the second triode is connected to the base of the third triode; The base of the first transistor is connected to the base of the fourth transistor; The emitter of the first triode is connected to the emitter of the second triode and the collector of the fifth triode; The emitter of the third triode is connected to the emitter of the fourth triode and the collector of the sixth triode; The emitter of the fifth transistor is connected to the emitter of the sixth transistor through the RC network; The emitter of the fifth triode is also grounded through the first current source; The emitter of the sixth triode is also grounded through the second current source; The RC network is used to compensate for the gain of the variable gain amplifier module.

6. The gain control circuit according to claim 5, characterized in that: The driving module comprises: a reference current source and a first reference resistor; The first end and the second end of the reference current source are connected to a working power supply and a first end of the first reference resistor respectively; The first end of the first reference resistor is also connected to the first input end of the adjustment module; A second terminal of the first reference resistor is grounded.

7. The gain control circuit according to claim 6, characterized in that: The regulating module comprises: an operational amplifier, a second MOS tube and a second reference resistor; The source and drain of the second MOS tube are respectively connected to a working power supply and a first end of the second reference resistor; The gate of the second MOS tube is connected to the drain of the first MOS tube; The first end of the second reference resistor is also connected to the second input end of the operational amplifier; A second terminal of the second reference resistor is grounded.

8. The gain control circuit according to claim 4 or 7, characterized in that: The first resistor and the fourth resistor have the same parameters, the first transistor and the fourth transistor have the same parameters, the second transistor and the third transistor have the same parameters, and the first current source and the second current source have the same parameters.

9. The gain control circuit according to claim 8, characterized in that: The RC network includes: a fifth resistor and a first capacitor; The first end of the fifth resistor is connected to the emitter of the fifth transistor and the first end of the first capacitor; The second end of the fifth resistor is connected to the emitter of the sixth transistor and the second end of the first capacitor.

10. A communication device, characterized in that: The communication device applies the gain control circuit according to any one of claims 1 to 9.

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