Differential source follower circuit and voltage gain adjusting method thereof

Abstract

The invention provides a differential source follower circuit and a voltage gain adjusting method thereof. The differential source follower circuit comprises a differential circuit part, a bias circuit part and an auxiliary amplifying circuit part. Wherein the bias circuit part is used for providing a corresponding direct current working point for the differential circuit part; the auxiliary amplification circuit part is used for providing auxiliary amplification for the differential circuit part; and the differential circuit part is used for performing differential amplification processing on two differential input signals based on the bias circuit part and the auxiliary amplification circuit part so as to form two differential output signals. According to the differential source follower circuit provided by the invention, the problem that the voltage gain value of a traditional source follower is too small and cannot be adjusted in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit design, and more specifically, to a differential source follower circuit and a voltage gain adjustment method thereof. Background Art

[0002] Source Follower Circuit is a common amplifier circuit, also known as voltage follower circuit. Its main function is to amplify or reduce the voltage of the input signal and then output it. It can be said that the source follower circuit is a voltage scaler that can convert a high-impedance input signal into a low-impedance signal output to drive the next stage circuit or load.

[0003] The circuit structure of the traditional single-ended source follower is as follows: Figure 1 As shown, the single-ended source follower circuit includes two PMOS transistors, M0' and M2', wherein M0' is an amplifier tube, the input signal is input from the gate of M0', output from the source of M0', and the drain of M0' is grounded; M2' is a bias tube, and the gate of M2' is connected to a fixed bias voltage to provide a suitable DC operating point for M0'.

[0004] Depend on Figure 1 It can be seen that the calculation formula for the voltage gain of the traditional single-ended source follower circuit is as follows: ,

[0005] The calculation formula for the output resistance of the traditional single-ended source follower circuit is as follows: ,

[0006] In the above two formulas, represents the transconductance of M0', Represents the output resistance of M0'.

[0007] It can be seen from the above two formulas that the voltage gain of a traditional (single-ended) source follower is approximately 1, but slightly less than 1; however, too low a voltage gain (less than 1) limits the application scope of the source follower; and, the voltage gain of a traditional source follower is fixed and cannot be adjusted, and cannot be applied in application scenarios where the voltage gain changes.

[0008] Based on the above technical problems, a source follower circuit with adjustable voltage gain is urgently needed. Summary of the invention

[0009] In view of the above problems, an object of the present invention is to provide a differential source follower circuit to solve the problem that the voltage gain value of the traditional source follower in the prior art is too small and cannot be adjusted.

[0010] The present invention provides a differential source follower circuit, comprising a differential circuit part, a bias circuit part and an auxiliary amplifier circuit part; wherein: The bias circuit part is used to provide a corresponding DC operating point for the differential circuit part; The auxiliary amplifier circuit part is used to provide auxiliary amplification for the differential circuit part; The differential circuit part is used to perform differential amplification processing on two differential input signals based on the bias circuit part and the auxiliary amplifier circuit part to form two differential output signals; wherein the differential circuit part, the bias circuit part and the auxiliary amplifier circuit part each include two transistors; wherein the two transistors of the differential circuit part and the two transistors of the bias circuit part are transistors of the same channel type, and the two transistors of the differential circuit part and the two transistors of the auxiliary amplifier circuit part are transistors of different channel types; and, The two transistors included in the differential circuit part are respectively grouped with the two transistors of the auxiliary amplifier circuit part in a one-to-one correspondence; wherein the drains of the two grouped transistors are connected, and the gates of the two non-grouped transistors are connected and then connected to the corresponding differential input signal.

[0011] In addition, a preferred solution is that the differential circuit part includes a first transistor and a second transistor, the bias circuit part includes a third transistor and a fourth transistor, and the auxiliary amplifier circuit part includes a fifth transistor and a sixth transistor; wherein, The first transistor, the second transistor, the third transistor and the fourth transistor are PMOS transistors, the fifth transistor and the sixth transistor are NMOS transistors; and, The gate of the first transistor and the gate of the sixth transistor are both connected to the first differential input signal, the gate of the second transistor and the gate of the fifth transistor are both connected to the second differential input signal, the gate of the third transistor and the gate of the fourth transistor are both connected to a first fixed bias voltage, the source of the first transistor and the drain of the third transistor are both connected to the first differential output signal, the source of the second transistor and the drain of the fourth transistor are both connected to the second differential output signal, the drain of the first transistor is connected to the drain of the fifth transistor, the drain of the second transistor is connected to the drain of the sixth transistor, the source of the third transistor and the source of the fourth transistor are both connected to a power supply, and the source of the fifth transistor and the source of the sixth transistor are both grounded.

[0012] In addition, a preferred solution is that a variable resistor is connected between the first differential output signal and the second differential output signal.

[0013] In addition, the preferred solution is: The variable resistor includes a gate-controlled transmission gate.

[0014] In addition, a preferred solution is that the voltage gain calculation formula of the differential source follower circuit is: ,

[0015] in, and denote the transconductance of the first transistor and the fifth transistor respectively, and Respectively represent the output resistance of the first transistor and the fifth transistor, Indicates the resistance value of the variable resistor.

[0016] In addition, a preferred solution is that the differential circuit part includes a seventh transistor and an eighth transistor, the bias circuit part includes a ninth transistor and a tenth transistor, and the auxiliary amplifier circuit part includes an eleventh transistor and a twelfth transistor; wherein, The seventh transistor, the eighth transistor, the ninth transistor and the tenth transistor are NMOS transistors, the eleventh transistor and the twelfth transistor are PMOS transistors; and, The gate of the seventh transistor and the gate of the twelfth transistor are both connected to the third differential input signal, the gate of the eighth transistor and the gate of the eleventh transistor are both connected to the fourth differential input signal, the gate of the ninth transistor and the gate of the tenth transistor are both connected to the second fixed bias voltage, the source of the seventh transistor and the drain of the ninth transistor are both connected to the third differential output signal, the source of the eighth transistor and the drain of the tenth transistor are both connected to the fourth differential output signal, the drain of the seventh transistor is connected to the drain of the eleventh transistor, the drain of the eighth transistor is connected to the drain of the twelfth transistor, the source of the ninth transistor and the source of the tenth transistor are both grounded, and the source of the eleventh transistor and the source of the twelfth transistor are both connected to a power supply.

[0017] In addition, a preferred solution is that a variable resistor is connected between the third differential output signal and the fourth differential output signal.

[0018] Furthermore, it is preferred that the variable resistor comprises a gate-controlled transmission gate.

[0019] On the other hand, the present invention further provides a voltage gain adjustment method for the differential source follower circuit as described above, comprising: The resistance value of the variable resistor is adjusted to adjust the voltage gain of the differential source follower circuit.

[0020] In addition, a preferred solution is that the adjusting the resistance value of the variable resistor includes: Regulating the gate voltage of the transmission gate to adjust the on-resistance of the transmission gate; wherein, The on-resistance of the transmission gate is the resistance value of the variable resistor.

[0021] Compared with the prior art, the differential source follower circuit provided by the present invention can increase the voltage gain to 6dB, which is twice that of the traditional source follower circuit, and can significantly increase the voltage gain of the source follower circuit. In addition, the differential source follower circuit and the voltage gain adjustment method provided by the present invention can also adjust the voltage gain, thereby adapting to different voltage gain application scenarios.

[0022] In order to achieve the above and related purposes, one or more aspects of the present invention include features that will be described in detail later and are particularly pointed out in the claims. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all of these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] By referring to the following description and claims in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the accompanying drawings: Figure 1 It is the schematic diagram of the traditional single-ended source follower circuit; Figure 2 A schematic diagram of a first differential source follower circuit provided by an embodiment of the present invention; Figure 3 A schematic diagram of a second differential source follower circuit provided by an embodiment of the present invention; Figure 4 A schematic diagram of a small signal (corresponding to the first type of differential source follower circuit) equivalent circuit of a differential source follower circuit provided in an embodiment of the present invention.

[0024] In the accompanying drawings: the first transistor M1, the second transistor M2, the third transistor M3, the fourth transistor M4, the fifth transistor M5, the sixth transistor M6, the first differential input signal inp1, the second differential input signal inn1, the first differential output signal outp1, the second differential output signal outn1, the first fixed bias voltage vb1, the seventh transistor M7, the eighth transistor M8, the ninth transistor M9, the tenth transistor M10, the eleventh transistor M11, the twelfth transistor M12, the third differential input signal inp2, the fourth differential input signal inn2, and the second fixed bias voltage vb2.

[0025] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0026] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is apparent that these embodiments may also be implemented without these specific details. In other examples, for ease of describing one or more embodiments, known structures and devices are shown in the form of block diagrams.

[0027] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0028] The principle of the differential source follower circuit provided by the present invention is described in detail below in conjunction with the accompanying drawings. The main body of the differential source follower circuit provided by the present invention is a differential circuit structure, which mainly includes three parts, namely a differential circuit part, a bias circuit part and an auxiliary amplifier circuit part; wherein the bias circuit part is used to provide a corresponding DC operating point for the differential circuit part; the auxiliary amplifier circuit part is used to provide auxiliary amplification for the differential circuit part; the differential circuit part is used to perform differential amplification processing on two differential input signals based on the bias circuit part and the auxiliary amplifier circuit part to form two differential output signals; wherein the differential circuit part, the bias circuit part and the auxiliary amplifier circuit part each include two transistors; wherein the two transistors of the differential circuit part and the two transistors of the bias circuit part are transistors of the same channel type, and the two transistors of the differential circuit part and the two transistors of the auxiliary amplifier circuit part are transistors of different channel types ; and, the two transistors included in the differential circuit part are respectively grouped in a one-to-one correspondence with the two transistors of the auxiliary amplifier circuit part, wherein the drains of the two transistors in the group are connected, and the gates of the two transistors not in the group are connected and then connected to the corresponding differential input signal; the sources of the two transistors in the differential circuit part are respectively connected to the corresponding differential output signals; the gates of the two transistors in the bias circuit part are both connected to a fixed bias voltage, the drains of the two transistors in the bias circuit part are respectively connected to the corresponding differential output signals, the sources of the two transistors in the bias circuit part are commonly connected to a power supply (when the two transistors in the bias circuit part are PMOS transistors) or commonly connected to ground (when the two transistors in the bias circuit part are NMOS transistors); the sources of the two transistors in the auxiliary amplifier circuit part are commonly connected to ground (when the two transistors in the auxiliary amplifier circuit part are NMOS transistors) or commonly connected to a power supply (when the two transistors in the auxiliary amplifier circuit part are PMOS transistors).

[0029] For example, Figure 2 In the illustrated embodiment, M1 and M5 are defined as a group, and M2 and M6 are defined as a group. At this time, M1 and M6 are defined as non-grouped (respectively in the differential circuit part and the auxiliary amplifier circuit part), and M2 and M5 are defined as non-grouped (respectively in the differential circuit part and the auxiliary amplifier circuit part); the drains of the grouped M1 and M5 are connected, the drains of the grouped M2 and M6 are connected, the gates of the non-grouped M1 and M6 are connected to a differential input signal, and the gates of the non-grouped M2 and M5 are connected to another differential input signal.

[0030] For another example, Figure 3In the illustrated embodiment, M7 and M11 are defined as a group, and M8 and M12 are defined as a group. At this time, M7 and M12 are defined as non-grouped (respectively in the differential circuit part and the auxiliary amplifier circuit part), and M8 and M11 are defined as non-grouped (respectively in the differential circuit part and the auxiliary amplifier circuit part); the drains of the grouped M7 and M11 are connected, the drains of the grouped M8 and M12 are connected, the gates of the non-grouped M7 and M12 are connected to a differential input signal, and the gates of the non-grouped M8 and M11 are connected to another differential input signal.

[0031] Specifically, in order to realize the functions of each part in the differential source follower circuit provided by the present invention, the present invention provides two specific circuit designs. The schematic diagram of the first differential source follower circuit provided by the present invention is as follows: Figure 2 As shown by Figure 2 It can be seen that the first differential source follower circuit provided by the present invention mainly includes four PMOS transistors M1-M4 and two NMOS transistors M5 and M6; wherein, the differential circuit part includes a first transistor M1 and a second transistor M2, and the first transistor M1 and the second transistor M2 are amplifier tubes; the bias circuit part includes a third transistor M3 and a fourth transistor M4, and the third transistor M3 and the fourth transistor M4 are bias tubes; the auxiliary amplifier circuit part includes a fifth transistor M5 and a sixth transistor M6, and the fifth transistor M5 and the sixth transistor M6 are auxiliary amplifier tubes.

[0032] More specifically, the gate of the first transistor M1 and the gate of the sixth transistor M6 are both connected to the first differential input signal inp1, the gate of the second transistor M2 and the gate of the fifth transistor M5 are both connected to the second differential input signal inn1, the gate of the third transistor M3 and the gate of the fourth transistor M4 are both connected to the first fixed bias voltage vb1, the first fixed bias voltage vb1 is used to provide a suitable DC operating point for the circuit, the source of the first transistor M1 and the drain of the third transistor M3 are both connected to the first differential output signal outp1, the source of the second transistor M2 and the drain of the fourth transistor M4 are both connected to the second differential output signal outn1, the drain of the first transistor M1 is connected to the drain of the fifth transistor M5, the drain of the second transistor M2 is connected to the drain of the sixth transistor M6, the source of the third transistor M3 and the source of the fourth transistor M4 are both connected to the power supply, and the source of the fifth transistor M5 and the source of the sixth transistor M6 are both grounded.

[0033] A preliminary analysis of the schematic diagram of the first differential source follower circuit provided by the above-mentioned embodiment of the present invention shows that, under the drive of the first transistor M1 and the second transistor M2, based on the presence of the third transistor M3 and the fourth transistor M4 as bias transistors, when the first differential input signal inp1 increases (the corresponding second differential input signal inn1 decreases), the first differential output signal outp1 will initially increase (the corresponding second differential output signal outn1 will initially decrease). In addition, due to the presence of the fifth transistor M5 and the sixth transistor M6 as auxiliary amplifiers, the voltage of the drain of the fifth transistor M5 will increase (the corresponding drain voltage of the sixth transistor M6 will decrease), so that the first differential output signal outp1 will further increase (the corresponding second differential output signal outn1 will further decrease), thereby significantly improving the voltage gain of the differential source follower circuit provided by the present invention, and the voltage gain can be increased to 6dB.

[0034] Further, for the first differential source follower circuit provided by the embodiment of the present invention, in order to achieve controllable adjustment of its voltage gain, a variable resistor may be connected across the first differential output signal outp1 and the second differential output signal outn1. Specifically, in order to achieve resistance adjustment of the variable resistor, the variable resistor may include a gate-controlled transmission gate, and when the gate voltage vdac of the transmission gate changes under control, the on-resistance of the transmission gate will also change. Thus, the resistance adjustment of the variable resistor is achieved.

[0035] The schematic diagram of the second differential source follower circuit provided by the present invention is as follows: Figure 3 As shown by Figure 3It can be known that the differential circuit part may also include a seventh transistor M7 and an eighth transistor M8, the bias circuit part includes a ninth transistor M9 and a tenth transistor M10, and the auxiliary amplifier circuit part includes an eleventh transistor M11 and a twelfth transistor M12; wherein the seventh transistor M7, the eighth transistor M8, the ninth transistor M9 and the tenth transistor M10 are NMOS transistors, the eleventh transistor M11 and the twelfth transistor M12 are PMOS transistors; and the gate of the seventh transistor M7 and the gate of the twelfth transistor M12 are both connected to the third differential input signal inp2, and the gate of the eighth transistor M8 and the gate of the eleventh transistor M11 are both connected to the fourth differential input signal inp3. No. inn2, the gate of the ninth transistor M9 and the gate of the tenth transistor M10 are both connected to the second fixed bias voltage vb2, the source of the seventh transistor M7 and the drain of the ninth transistor M9 are both connected to the third differential output signal outp2, the source of the eighth transistor M8 and the drain of the tenth transistor M10 are both connected to the fourth differential output signal outn2, the drain of the seventh transistor M7 is connected to the drain of the eleventh transistor M11, the drain of the eighth transistor M8 is connected to the drain of the twelfth transistor M12, the source of the ninth transistor M9 and the source of the tenth transistor M10 are both grounded, and the source of the eleventh transistor M11 and the source of the twelfth transistor M12 are both connected to the power supply.

[0036] Of course, for the second differential source follower circuit provided by the embodiment of the present invention, in order to achieve controllable adjustment of its voltage gain, a variable resistor may be connected across the third differential output signal outp2 and the fourth differential output signal outn2. Specifically, in order to achieve resistance adjustment of the variable resistor, the variable resistor may include a gate-controlled transmission gate, and when the gate voltage vdac of the transmission gate changes under control, the on-resistance of the transmission gate also changes, thereby achieving resistance adjustment of the variable resistor.

[0037] It is worth mentioning that Figure 2 The circuit structure described is the PMOS input. Correspondingly, Figure 3 The circuit structure of NMOS input is described; these two structures have the same function and internal logic and should be within the scope of protection of this patent.

[0038] To further illustrate the working principle of the differential source follower circuit provided by the present invention, Figure 4 The single-ended small signal equivalent circuit of the differential source follower circuit provided by the embodiment of the present invention is shown (the equivalent circuit corresponds to Figure 2 The first differential source follower circuit shown, Figure 3The principle of the second differential source follower circuit shown is the same as that of the first differential source follower circuit shown in FIG. 1 ), and the voltage gain calculation formula of the differential source follower circuit provided by the present invention can be obtained by analyzing and calculating the voltage gain of the differential source follower circuit provided by the present invention: ,

[0039] in, Indicates the output voltage, Indicates the input voltage, and denote the transconductance of the first transistor and the fifth transistor respectively, and Respectively represent the output resistance of the first transistor and the fifth transistor, Indicates the resistance value of the variable resistor. It should be noted that due to Figure 4 for Figure 2 FIG. 4 shows an equivalent circuit of a first differential source follower circuit provided by an embodiment of the present invention. Therefore, in Figure 4 middle, Corresponding to outp1, Corresponding to inp1.

[0040] The voltage gain formula of the differential source follower circuit provided by the present invention is compared with the voltage gain calculation formula of the traditional single-ended source follower circuit mentioned in the background technology of this application. and When the voltage gain of the differential source follower circuit provided by the present invention is approximately equal (which is satisfied in most cases), it is 6 dB, which is twice that of the traditional source follower circuit. (the resistance of the variable resistor) is proportional to the The value of can realize the adjustment of voltage gain. At the same time, voltage gain and load Proportional to change The value of can realize the adjustment of voltage gain.

[0041] In addition, the output resistance calculation formula is the value of Vo divided by the output current when the input voltage is 0. Therefore, Figure 4 Further analysis and calculation can show that the calculation formula for the output resistance of the differential source follower circuit provided by the present invention is: .

[0042] The calculation formula of the output resistance of the differential source follower circuit provided by the present invention is compared with the calculation formula of the output resistance of the traditional single-ended source follower circuit mentioned in the background technology of the present application. When it is large enough (which is satisfied in most cases), the output resistance of the differential source follower circuit provided by the present invention is substantially the same as that of a conventional source follower circuit, and the wide bandwidth characteristic of the source follower can be maintained.

[0043] On the other hand, in order to further illustrate the specific adjustment principle of the differential source follower circuit provided by the present invention, the present invention also provides a voltage gain adjustment method of the differential source follower circuit as described above, and the voltage gain adjustment method is applicable to the above two differential source follower circuits provided by the present invention, and the voltage gain adjustment method includes: The resistance value of the variable resistor is adjusted to adjust the voltage gain of the differential source follower circuit.

[0044] Furthermore, the specific process of adjusting the resistance value of the variable resistor includes: The gate voltage of the transmission gate is adjusted to adjust the on-resistance of the transmission gate; wherein, The on-resistance of the transmission gate is the resistance of the variable resistor.

[0045] As described above with reference to the accompanying drawings, the differential source follower circuit and the gain adjustment method thereof according to the present invention are described in an exemplary manner. However, those skilled in the art should understand that various improvements can be made to the differential source follower circuit and the gain adjustment method thereof proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A differential source follower circuit, characterized in that: It includes a differential circuit part, a bias circuit part and an auxiliary amplifier circuit part; wherein, The bias circuit part is used to provide a corresponding DC operating point for the differential circuit part; The auxiliary amplifier circuit part is used to provide auxiliary amplification for the differential circuit part; The differential circuit part is used to perform differential amplification processing on two differential input signals based on the bias circuit part and the auxiliary amplifier circuit part to form two differential output signals; wherein, The differential circuit part, the bias circuit part and the auxiliary amplifier circuit part each include two transistors; wherein the two transistors of the differential circuit part and the two transistors of the bias circuit part are transistors of the same channel type, and the two transistors of the differential circuit part and the two transistors of the auxiliary amplifier circuit part are transistors of different channel types; and, The two transistors included in the differential circuit part are respectively grouped with the two transistors of the auxiliary amplifier circuit part in a one-to-one correspondence; wherein the drains of the two grouped transistors are connected, and the gates of the two non-grouped transistors are connected and then connected to the corresponding differential input signal.

2. The differential source follower circuit according to claim 1, characterized in that: The differential circuit part includes a first transistor and a second transistor, the bias circuit part includes a third transistor and a fourth transistor, and the auxiliary amplifier circuit part includes a fifth transistor and a sixth transistor; wherein, The first transistor, the second transistor, the third transistor and the fourth transistor are PMOS transistors, the fifth transistor and the sixth transistor are NMOS transistors; and, The gate of the first transistor and the gate of the sixth transistor are both connected to the first differential input signal, the gate of the second transistor and the gate of the fifth transistor are both connected to the second differential input signal, the gate of the third transistor and the gate of the fourth transistor are both connected to a first fixed bias voltage, the source of the first transistor and the drain of the third transistor are both connected to the first differential output signal, the source of the second transistor and the drain of the fourth transistor are both connected to the second differential output signal, the drain of the first transistor is connected to the drain of the fifth transistor, the drain of the second transistor is connected to the drain of the sixth transistor, the source of the third transistor and the source of the fourth transistor are both connected to a power supply, and the source of the fifth transistor and the source of the sixth transistor are both grounded.

3. The differential source follower circuit according to claim 2, characterized in that: A variable resistor is connected between the first differential output signal and the second differential output signal.

4. The differential source follower circuit according to claim 3, characterized in that: The variable resistor includes a gate-controlled transmission gate.

5. The differential source follower circuit according to claim 4, characterized in that: The voltage gain calculation formula of the differential source follower circuit is: ， in, and denote the transconductance of the first transistor and the fifth transistor respectively, and Respectively represent the output resistance of the first transistor and the fifth transistor, Indicates the resistance value of the variable resistor.

6. The differential source follower circuit according to claim 1, characterized in that: The differential circuit part includes a seventh transistor and an eighth transistor, the bias circuit part includes a ninth transistor and a tenth transistor, and the auxiliary amplifier circuit part includes an eleventh transistor and a twelfth transistor; wherein, The seventh transistor, the eighth transistor, the ninth transistor and the tenth transistor are NMOS transistors, the eleventh transistor and the twelfth transistor are PMOS transistors; and, The gate of the seventh transistor and the gate of the twelfth transistor are both connected to the third differential input signal, the gate of the eighth transistor and the gate of the eleventh transistor are both connected to the fourth differential input signal, the gate of the ninth transistor and the gate of the tenth transistor are both connected to the second fixed bias voltage, the source of the seventh transistor and the drain of the ninth transistor are both connected to the third differential output signal, the source of the eighth transistor and the drain of the tenth transistor are both connected to the fourth differential output signal, the drain of the seventh transistor is connected to the drain of the eleventh transistor, the drain of the eighth transistor is connected to the drain of the twelfth transistor, the source of the ninth transistor and the source of the tenth transistor are both grounded, and the source of the eleventh transistor and the source of the twelfth transistor are both connected to a power supply.

7. The differential source follower circuit according to claim 6, characterized in that: A variable resistor is connected between the third differential output signal and the fourth differential output signal.

8. The differential source follower circuit according to claim 7, characterized in that: The variable resistor includes a gate-controlled transmission gate.

9. A voltage gain adjustment method for a differential source follower circuit as claimed in any one of claims 1 to 8, characterized in that: include: The resistance value of the variable resistor is adjusted to adjust the voltage gain of the differential source follower circuit.

10. The voltage gain adjustment method of the differential source follower circuit according to claim 9, characterized in that: The step of adjusting the resistance value of the variable resistor comprises: Regulating the gate voltage of the transmission gate to adjust the on-resistance of the transmission gate; wherein, The on-resistance of the transmission gate is the resistance value of the variable resistor.

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