Transimpedance amplifier circuit and optical communication system

Abstract

The present invention discloses a transimpedance amplifier circuit and an optical communication system. The transimpedance amplifier circuit includes: an amplifier, a feedback circuit and a gain adjustment circuit; the feedback circuit is connected to the input end of the amplifier and the output end of the amplifier, and the gain adjustment circuit includes a current replication unit, an adjustable resistance unit and a control unit. The current replication unit is used to replicate the DC component of the input signal of the amplifier to generate a first current. The adjustable resistance unit generates a first voltage based on the first current. The control unit is used to generate a control voltage based on a reference voltage to adjust the resistance of the adjustable resistance unit. The control unit is also connected to the feedback circuit of the amplifier, and the feedback circuit of the amplifier is used to receive the control voltage and generate a feedback voltage proportional to the first voltage based on the control of the control voltage. The transimpedance amplifier circuit and the optical communication system of the present invention can automatically adjust the gain of the transimpedance amplifier circuit to ensure the stability and monotonicity of the output signal amplitude.

Description

Technical Field

[0001] The present invention belongs to the technical field of transimpedance amplifier circuits, and in particular relates to a transimpedance amplifier circuit and an optical communication system. Background Art

[0002] A transimpedance amplifier (TIA) is a circuit used at the receiving end of an optical communication system to convert received optical signals into voltage signals. The strength of the received signal in a transimpedance amplifier circuit varies widely, and the minimum and maximum signal strengths may differ by dozens to hundreds of times. Therefore, the transimpedance of the circuit needs to be adjusted with the size of the input signal to ensure the stability of the output waveform amplitude.

[0003] The input current signal of the transimpedance amplifier circuit includes direct current (DC) and alternating current (AC), and the DC and AC currents are in a linear relationship. Figure 1 The figure shows the basic circuit structure of the transimpedance amplifier circuit. The DC part Iin_dc of the input current is separated and flows to the ground through the transistor Mdc, while the AC part Iin_ac is converted into an output signal through a feedback circuit composed of a feedback resistor Rf and a feedback transistor Mgc. When a large signal is input, the feedback transistor Mgc is turned on and connected in parallel with the feedback resistor Rf to generate a smaller transimpedance. At this time, the amplitude of the output signal is Iin_ac×(Rf∥Mgc), where Rf∥Mgc is the equivalent resistance of the feedback resistor Rf and the feedback transistor Mgc. The output signal amplitude can be adjusted by adjusting the on-resistance of the feedback transistor Mgc, that is, the gain of the transimpedance amplifier circuit can be adjusted, and the size of the on-resistance of the feedback transistor Mgc is adjusted by its gate voltage vgc.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The object of the present invention is to provide a transimpedance amplifier circuit and an optical communication system, which can automatically adjust the gain of the transimpedance amplifier circuit.

[0006] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0007] A transimpedance amplifier circuit, characterized in that it comprises: an amplifier, a feedback circuit and a gain adjustment circuit; the feedback circuit is connected to an input end of the amplifier and an output end of the amplifier, and the gain adjustment circuit comprises:

[0008] A current replication unit, connected to the input end of the amplifier, for sampling the DC component of the input signal of the amplifier and replicating it to generate a first current;

[0009] an adjustable resistance unit, the adjustable resistance unit being connected to the current replication unit to generate a first voltage based on the first current;

[0010] A control unit is connected to the adjustable resistance unit and the feedback circuit, and is used to generate a control voltage based on the first voltage and the reference voltage, so as to adjust the resistance of the adjustable resistance unit and the resistance of the feedback circuit by the control voltage, so that the first voltage, the feedback voltage of the feedback circuit and the reference voltage are proportional.

[0011] In one or more embodiments of the present invention, the adjustable resistance unit includes a first transistor and a first resistor, the first end of the first transistor and the first end of the first resistor are connected to a control unit, the second end of the first transistor and the second end of the first resistor are connected to a current replication unit and the control unit to generate a first voltage, and the control end of the first transistor is connected to the control unit to receive the control voltage.

[0012] In one or more embodiments of the present invention, the control unit includes a first amplifier and a reference voltage generating unit, the reference voltage generating unit is used to generate a reference voltage, the first input terminal of the first amplifier is connected to the adjustable resistance unit to receive the first voltage, the second input terminal of the first amplifier is connected to the reference voltage generating unit to receive the reference voltage, and the output terminal of the first amplifier is connected to the adjustable resistance unit to generate a control voltage.

[0013] In one or more embodiments of the present invention, the reference voltage generating unit includes a current source and a second resistor connected to each other, the current source is used to generate a reference current, and the second resistor is used to generate a reference voltage based on the reference current.

[0014] In one or more embodiments of the present invention, the gain adjustment circuit also includes a voltage clamping unit, which is connected to the adjustable resistance unit, the control unit and the input end of the amplifier, and the voltage clamping unit is used to clamp the reference potential of the first voltage and the reference voltage to the input voltage of the amplifier.

[0015] In one or more embodiments of the present invention, the voltage clamping unit includes a second amplifier and a second transistor, the first input terminal of the second amplifier and the second terminal of the second transistor are connected to the adjustable resistance unit and the control unit, the second input terminal of the second amplifier is connected to the input terminal of the amplifier, the output terminal of the second amplifier is connected to the control terminal of the second transistor, and the first terminal of the second transistor is connected to the ground voltage.

[0016] In one or more embodiments of the present invention, the current replication unit includes a current sampling unit and a current mirror unit, wherein the current sampling unit is connected to the input end of the amplifier to sample the DC component of the input signal of the amplifier and generate a sampling current, and the current mirror unit is connected to the current sampling unit to replicate the sampling current to generate a first current.

[0017] In one or more embodiments of the present invention, the current sampling unit includes a third transistor, a second end of the third transistor is connected to the input end of the amplifier, a first end of the third transistor is connected to the ground voltage, and a control end of the third transistor is used to receive a sampling control voltage.

[0018] In one or more embodiments of the present invention, the current mirror unit includes a fourth transistor, a fifth transistor and a sixth transistor, the control end of the fourth transistor is connected to the current sampling unit, the first end of the fourth transistor is connected to the ground voltage, the second end of the fourth transistor is connected to the second end of the fifth transistor, the first end of the fifth transistor and the first end of the sixth transistor are connected to the power supply voltage, the control end of the fifth transistor is connected to the second end of the fifth transistor and the control end of the sixth transistor, and the second end of the sixth transistor is used to output the first current.

[0019] The invention also discloses an optical communication system, comprising the transimpedance amplifier circuit.

[0020] Compared with the prior art, the transimpedance amplifier circuit and optical communication system of the present invention can automatically adjust the gain of the transimpedance amplifier circuit to stabilize it at a desired value, thereby ensuring the stability and monotonicity of the output signal amplitude and avoiding the non-monotonic problem that the transimpedance decreases sharply in certain control voltage regions, causing the output signal to decrease as the input signal increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention 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, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a circuit schematic diagram of a transimpedance amplifier circuit in the prior art.

[0023] Figure 2 FIG. 4 is a circuit schematic diagram of an optical communication system in one embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] "Coupled" or "connected" or "connected" in the specification includes both direct connection and indirect connection. Indirect connection is a connection through an intermediate medium, such as a connection through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connection may also include connection through other active or passive devices on the basis of achieving the same or similar functional purposes, such as connection through circuits or components such as switches and follower circuits. In addition, in the invention, words such as "first" and "second" are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply that there is a certain actual relationship, quantity or order between these technical features.

[0026] In the detailed description of the specification, reference is made to the accompanying drawings forming a part thereof, wherein like reference numerals refer to like parts throughout, and wherein are shown by way of exemplary embodiments that may be implemented. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be considered in a limiting sense.

[0027] The various operations in the specification may be described in turn as multiple discrete actions or operations in a manner that is most helpful in understanding the claimed subject matter. However, the order of description should not be interpreted as implying that these operations must be order-dependent. Specifically, these operations may not be performed in the order presented. The described operations may be performed in an order different from the described embodiments. Various additional operations may be performed and / or the described operations may be omitted in additional embodiments.

[0028] For purposes of this disclosure, the phrase "A and / or B" means (A), (B), or (A and B). For purposes of this disclosure, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0029] Various components and devices may be referred to or shown in the singular form in this document (for example, "MOS tube", "transistor", "switch", etc.), but this is only for convenience of discussion, and any element mentioned in the singular form may include multiple such elements according to the teachings of this document.

[0030] The specification describes the use of the phrases "in one embodiment" or "in other embodiments" or "in some embodiments", which may each refer to one or more of the same or different embodiments. In addition, the terms "including", "comprising", "having", etc. used in relation to the embodiments of the present disclosure are synonymous.

[0031] like Figure 2 As shown, in a transimpedance amplifier circuit in an embodiment of the present invention, the input terminal in of the transimpedance amplifier circuit is used to receive an input signal (such as an optical signal), and the transimpedance amplifier circuit is used to convert the AC component Iin_ac of the input signal into a voltage signal.

[0032] The transimpedance amplifier circuit includes an amplifier A3, a feedback circuit and a gain adjustment circuit. The feedback circuit is connected to the input end of the amplifier A3 and the output end of the amplifier A3. The gain adjustment circuit is connected to the input end of the amplifier A3 and the feedback circuit, and the gain adjustment circuit is used to generate a control voltage vgc based on the DC component lin_dc of the optical signal. The input end of the amplifier A3 is also the input end in of the transimpedance amplifier circuit.

[0033] The feedback circuit includes a feedback transistor Mgc and a feedback resistor Rf. The first end of the feedback transistor Mgc and the first end of the feedback resistor Rf are connected to the input end of the amplifier A3 and form the input end in of the transimpedance amplifier circuit. The second end of the feedback transistor Mgc and the second end of the feedback resistor Rf are connected to the output end of the amplifier A3 and form the input end out of the transimpedance amplifier circuit. The control end of the feedback transistor Mgc is used to receive the control voltage vgc.

[0034] like Figure 2 As shown, the gain adjustment circuit includes a current replication unit 10 , an adjustable resistance unit 20 , a control unit 30 and a voltage clamping unit 40 .

[0035] The current replication unit 10 is connected to the input terminal in of the amplifier A3 and is used to sample the DC component Iin_dc of the input signal and replicate it to generate a first current.

[0036] In one embodiment, the AC component Iin_ac and the DC component Iin_dc of the input signal are in a linear relationship. In other embodiments, the transimpedance amplifier circuit can also be used to receive and process a DC signal, and the current replication unit 10 is used to replicate the components of the DC signal.

[0037] The adjustable resistance unit 20 is connected to the current replication unit 10 to generate a first voltage based on the first current.

[0038] The control unit 30 is connected to the adjustable resistance unit 20 and the feedback circuit, and is used to generate a control voltage vgc based on the first voltage and the reference voltage vamp, so as to adjust the resistance of the adjustable resistance unit 20 and the resistance of the feedback circuit through the control voltage vgc, so that the first voltage, the feedback voltage of the feedback circuit are proportional to the reference voltage vamp.

[0039] In one embodiment, the first voltage is equal to the reference voltage vamp, and the feedback circuit generates a feedback voltage proportional to the first voltage, and the feedback voltage and the first voltage are not equal but proportional. The control unit 30 is connected to the control end of the feedback transistor Mgc of the feedback circuit, and the resistance of the feedback circuit is adjusted by controlling the feedback transistor Mgc, so that the feedback circuit generates a feedback voltage proportional to the first voltage. In other embodiments, the feedback voltage can also be equal to the reference voltage vamp, the first voltage is not equal to the reference voltage vamp but proportional, or the first voltage, the feedback voltage and the reference voltage vamp are not equal but proportional.

[0040] The voltage clamping unit 40 is connected to the adjustable resistance unit 20, the control unit 30 and the input terminal in of the amplifier A3, and is used to clamp the reference potential of the first voltage and the reference voltage vamp to the input terminal voltage of the amplifier A3.

[0041] like Figure 2 As shown, the current replication unit 10 includes a current sampling unit and a current mirror unit. The current sampling unit is connected to the input end of the amplifier A3 to sample the DC component of the input signal of the amplifier A3 and generate a sampling current. The current mirror unit is connected to the current sampling unit to replicate the sampling current to generate a first current.

[0042] In one embodiment, the current sampling unit includes a third transistor M3. A first end of the third transistor M3 is connected to a ground voltage, a second end of the third transistor M3 is connected to an input end of the amplifier A3, and a control end of the third transistor M3 is used to receive a sampling control voltage vdcr. The third transistor M3 is controlled by the sampling control voltage vdcr, so that the current flowing through the third transistor M3 is a sampling current proportional to the DC component Iin_dc. The sampling control voltage vdcr can be generated by a sampling control circuit (not shown in the figure) based on the DC component Iin_dc of the input signal.

[0043] The current mirror unit includes a fourth transistor M4, a fifth transistor M5 and a sixth transistor M6. The control end of the fourth transistor M4 is connected to the control end of the third transistor M3 of the current sampling unit, and the control end of the fourth transistor M4 is used to receive the sampling control voltage vdcr. The third transistor M3 and the fourth transistor M4 both work in the saturation region. The first end of the fourth transistor M4 is connected to the ground voltage, the second end of the fourth transistor M4 is connected to the second end of the fifth transistor M5, the first end of the fifth transistor M5 and the first end of the sixth transistor M6 are connected to the power supply voltage, the control end of the fifth transistor M5 is connected to the second end of the fifth transistor M5 and the control end of the sixth transistor M6, and the second end of the sixth transistor M6 is connected to the first end of the adjustable resistance unit 20 for outputting the first current.

[0044] In one embodiment, the width-to-length ratio of the third transistor M3 and the fourth transistor M4 is 1:m, and the replication ratio of the current mirror unit is 1:1, that is, the ratio of the first current to the DC component Iin_dc of the input signal is m. In other embodiments, the current replication ratio can be adjusted as needed.

[0045] In other embodiments, the current replication unit may also include a first current mirror and a second current mirror connected to each other, the first current mirror being connected to the input end of the amplifier A3 to replicate the DC component of the input signal of the amplifier A3 to generate a replicated current, and the second current mirror being connected to the first end of the adjustable resistance unit, and the second current mirror being used to replicate the replicated current to generate a first current.

[0046] like Figure 2 As shown, the adjustable resistance unit 20 includes a first transistor M1 and a first resistor R1. The first end of the first resistor R1 and the first end of the first transistor M1 are connected to the control unit 30 and the voltage clamping unit 40, the second end of the first resistor R1 and the second end of the first transistor M1 are connected to the second end of the sixth transistor M6 and the control unit 30, and the control end of the first transistor M1 is connected to the control unit 30 to receive the control voltage vgc.

[0047] In one embodiment, the first transistor M1 and the feedback transistor Mgc, the first resistor R1 and the feedback resistor Rf are mirrored in proportion, and under the control of the same control voltage vgc, the ratio of the equivalent resistance of the first transistor M1 and the first resistor R1 to the equivalent resistance of the feedback transistor Mgc and the feedback resistor Rf is constant. The ratio of the first transistor M1 to the feedback transistor Mgc, the first resistor R1 to the feedback resistor Rf can be adjusted as needed, so as to determine the ratio between the first voltage, the feedback voltage and the reference voltage vamp.

[0048] like Figure 2As shown, the control unit 30 includes a first amplifier A1 and a reference voltage generating unit. The reference voltage generating unit is used to generate a reference voltage vamp, a first input terminal of the first amplifier A1 is connected to a second terminal of the first transistor M1 to receive a first voltage, a second input terminal of the first amplifier A1 is connected to the reference voltage generating unit to receive the reference voltage vamp, and an output terminal of the first amplifier A1 is connected to a control terminal of the first transistor M1 to generate a control voltage vgc.

[0049] In one embodiment, the first input terminal of the first amplifier A1 is a non-inverting input terminal, and the second input terminal of the first amplifier A1 is an inverting input terminal.

[0050] The reference voltage generating unit includes a current source I1 and a second resistor R2. A first end of the current source I1 is connected to a power supply voltage, a second end of the current source I1 is connected to a first end of a second resistor R2 to output a reference current, a first end of the second resistor R2 is connected to a second input end of a second amplifier A2, a second end of the second resistor R2 is connected to a first end of the first resistor R1 and a first end of a first transistor M1, and the second resistor R2 is used to generate a reference voltage vamp at a second input end of the first amplifier A1 based on the reference current.

[0051] like Figure 2 As shown, the voltage clamping unit 40 includes a second amplifier A2 and a second transistor M2. The first input terminal of the second amplifier A2 and the second terminal of the second transistor M2 are connected to the first terminal of the first transistor M1, the second input terminal of the second amplifier A2 is connected to the input terminal in of the amplifier A3, the output terminal of the second amplifier A2 is connected to the control terminal of the second transistor M2, and the first terminal of the second transistor M2 is connected to the ground voltage.

[0052] In one embodiment, the first input terminal of the second amplifier A2 is a non-inverting input terminal, and the second input terminal of the second amplifier A2 is an inverting input terminal. Under the feedback loop regulation of the second amplifier A2, the voltage of the first terminal of the first transistor M1 is equal to the voltage of the input terminal in of the amplifier A3, that is, the reference potential of the first voltage and the reference voltage vamp is equal to the voltage of the input terminal in of the amplifier A3.

[0053] In one embodiment, the first transistor M1, the second transistor M2, the third transistor M3, the fourth transistor M4 and the feedback transistor Mgc are NMOS transistors, and the fifth transistor M5 and the sixth transistor M6 are PMOS transistors. In other embodiments, the first transistor M1, the second transistor M2, the third transistor M3, the fourth transistor M4 and the feedback transistor Mgc may also be PMOS transistors or other devices, and the fifth transistor M5 and the sixth transistor M6 may also be NMOS transistors or other devices, and their connection methods may be adaptively adjusted.

[0054] A first end of the first transistor M1, a first end of the second transistor M2, a first end of the third transistor M3, a first end of the fourth transistor M4, a first end of the fifth transistor M5, a first end of the sixth transistor M6 and a first end of the feedback transistor Mgc are sources.

[0055] The second end of the first transistor M1, the second end of the second transistor M2, the second end of the third transistor M3, the second end of the fourth transistor M4, the second end of the fifth transistor M5, the second end of the sixth transistor M6 and the second end of the feedback transistor Mgc are drains.

[0056] The control end of the first transistor M1, the control end of the second transistor M2, the control end of the third transistor M3, the control end of the fourth transistor M4, the control end of the fifth transistor M5, the control end of the sixth transistor M6 and the control end of the feedback transistor Mgc are gates.

[0057] In the actual working process, the first current copied by the current copying unit 10 is m×Iin_dc, and the voltage difference generated by the first current at the first end and the second end of the first transistor M1 is m×Iin_dc×(R1||M1), where R1||M1 is the equivalent resistance formed by the first transistor M1 and the first resistor R1. The control voltage vgc is generated by the feedback loop of the first amplifier A1 to control the gate voltage of the first transistor M1, thereby controlling the on-resistance of the first transistor M1, so that the first voltage is always equal to the reference voltage vamp, that is, m×Iin_dc×(R1||M1)=vamp. Since the reference voltage vamp is a set constant voltage value, which is equal to or linearly related to the target amplitude of the output signal of the amplifier A3, and the set value is generally small, when the amplifier A3 inputs a large signal, the first transistor M1 operates in the linear region, and at this time, the DC equivalent resistance and the AC equivalent resistance of the first transistor M1 can be considered to be basically equal.

[0058] At the same time, since the first transistor M1 and the feedback transistor Mgc, and the first resistor R1 and the feedback resistor Rf are proportional mirror devices, and the feedback transistor Mgc also works in the linear region. Under the control of the control voltage vgc, the equivalent resistance formed by the feedback transistor Mgc and the feedback resistor Rf is in a fixed proportional relationship with the equivalent resistance formed by the first transistor M1 and the first resistor R1. The voltage clamping unit 40 makes the source voltage of the first transistor M1 the same as the source voltage of the feedback transistor Mgc, further improving the accuracy of the transimpedance. It can be obtained that Iin_ac×(Rf∥Mgc)=k×vamp, where k is the set proportional coefficient. Under the changing input signal, the gain adjustment circuit can also automatically adjust the control voltage vgc to ensure the stability and monotonicity of the output signal amplitude of the amplifier A3, and there will be no non-monotonicity that the output signal decreases as the input signal increases due to the sharp decrease in transimpedance in certain control voltage vgc regions.

[0059] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0060] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A transimpedance amplifier circuit, characterized in that: include: amplifiers, feedback circuits, and gain adjustment circuits; The feedback circuit is connected to the input end of the amplifier and the output end of the amplifier, and the gain adjustment circuit includes: A current replication unit, connected to the input end of the amplifier, for sampling the DC component of the input signal of the amplifier and replicating it to generate a first current; an adjustable resistance unit, the adjustable resistance unit being connected to the current replication unit to generate a first voltage based on the first current; a control unit connected to the adjustable resistance unit and the feedback circuit, and configured to generate a control voltage based on the first voltage and the reference voltage, so as to adjust the resistance of the adjustable resistance unit and the resistance of the feedback circuit by the control voltage, so that the first voltage, the feedback voltage of the feedback circuit and the reference voltage are proportional to each other; The adjustable resistance unit includes a first transistor and a first resistor, and the control unit includes a first amplifier and a reference voltage generating unit. The reference voltage generating unit is used to generate a reference voltage. The second end of the first transistor and the second end of the first resistor are connected to the current replication unit and the first input end of the first amplifier to generate a first voltage. The first end of the first transistor and the first end of the first resistor are connected and the second input end of the first amplifier are respectively connected to the reference voltage generating unit to receive the reference voltage. The voltage difference between the second input end of the first amplifier and the first end of the connected first transistor and the first end of the first resistor is the reference voltage. The control end of the first transistor is connected to the output end of the first amplifier to receive the control voltage.

2. The transimpedance amplifier circuit according to claim 1, characterized in that: The reference voltage generating unit includes a current source and a second resistor connected to each other, the current source is used to generate a reference current, and the second resistor is used to generate a reference voltage based on the reference current.

3. The transimpedance amplifier circuit according to claim 1, characterized in that: The gain adjustment circuit also includes a voltage clamping unit, which is connected to the adjustable resistance unit, the control unit and the input end of the amplifier, and is used to clamp the reference potential of the first voltage and the reference voltage to the input end voltage of the amplifier.

4. The transimpedance amplifier circuit according to claim 3, characterized in that: The voltage clamping unit includes a second amplifier and a second transistor, the first input end of the second amplifier and the second end of the second transistor are connected to the adjustable resistance unit and the control unit, the second input end of the second amplifier is connected to the input end of the amplifier, the output end of the second amplifier is connected to the control end of the second transistor, and the first end of the second transistor is connected to the ground voltage.

5. The transimpedance amplifier circuit according to claim 1, characterized in that: The current copy unit includes a current sampling unit and a current mirror unit. The current sampling unit is connected to the input end of the amplifier to sample the DC component of the input signal of the amplifier and generate a sampling current. The current mirror unit is connected to the current sampling unit to copy the sampling current to generate a first current.

6. The transimpedance amplifier circuit according to claim 5, characterized in that: The current sampling unit comprises a third transistor, a second terminal of the third transistor is connected to the input terminal of the amplifier, a first terminal of the third transistor is connected to the ground voltage, and a control terminal of the third transistor is used to receive a sampling control voltage.

7. The transimpedance amplifier circuit according to claim 5, characterized in that: The current mirror unit includes a fourth transistor, a fifth transistor and a sixth transistor, the control end of the fourth transistor is connected to the current sampling unit, the first end of the fourth transistor is connected to the ground voltage, the second end of the fourth transistor is connected to the second end of the fifth transistor, the first end of the fifth transistor and the first end of the sixth transistor are connected to the power supply voltage, the control end of the fifth transistor is connected to the second end of the fifth transistor and the control end of the sixth transistor, and the second end of the sixth transistor is used to output the first current.

8. An optical communication system, characterized in that: The invention comprises the transimpedance amplifier circuit according to any one of claims 1 to 7.

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