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CN-122001309-A - Gain-variable type variable gain device transimpedance amplifier circuit

CN122001309ACN 122001309 ACN122001309 ACN 122001309ACN-122001309-A

Abstract

The invention relates to a variable gain transimpedance amplifier circuit, which comprises a photoelectric conversion element, an operational amplifier, a transimpedance component and a bypass component. The invention realizes the adjustment of the whole resistance value of the transimpedance component by utilizing the design of the bypass component, thereby enlarging the adjustable range of the resistance value of the transimpedance component, further realizing the wide variable gain of the transimpedance and being suitable for large-range optical power detection. Meanwhile, the invention also realizes the bypass of the series resistance of the transimpedance component through the design of the bypass component, so that the minimum resistance value of a resistance of the transimpedance component in the resistance adjustment range is equal to the sum of the resistance values of all the resistances.

Inventors

  • CAO SIYI
  • QIU CHEN
  • TU CHUANJIE
  • YU JIEKUI

Assignees

  • 武汉光迅科技股份有限公司

Dates

Publication Date
20260508
Application Date
20241105

Claims (10)

  1. 1. A variable gain transimpedance amplifier circuit, characterized by comprising the following steps: the photoelectric conversion element is arranged in front of the current input node; the operational amplifier is arranged between the current input node and the voltage output node; the transimpedance component is arranged in parallel with the operational amplifier and comprises n resistors arranged in series; And the bypass component is used for controlling the bypass of 1-n-1 resistors of the transimpedance component.
  2. 2. The variable gain transimpedance amplifier circuit according to claim 1, wherein the bypass component comprises a multiplexer having n-1 paths, 1 first conductor without a switch, and n-1 second conductors with a switch; One end of the first wire is connected to the common path of the multiplexer, the other end is connected to the connecting node at any resistor, one end of the n-1 second wires is connected with n-1 branches of the multiplexer, and the other ends are connected to the other n-1 connecting nodes of the transimpedance assembly.
  3. 3. A variable gain transimpedance amplifier circuit according to claim 2, wherein said multiplexer comprises an EN pin and an ADDR address pin; when the EN pin acquires a low level, the switches of the n-1 branches are controlled to be disconnected; when the pin EN acquires high level, the ADDR address pin selects any one of the switches of the corresponding branch circuits to be closed.
  4. 4. A variable gain transimpedance amplifier circuit according to claim 3, wherein the multiplexer comprises an MCU element.
  5. 5. A variable gain transimpedance amplifier circuit according to claim 4, it is characterized in that the method is characterized in that, When the output of the driving controller is high level, the address is allocated to the ADDR address pin according to the magnitude of the optical power.
  6. 6. The variable gain transimpedance amplifier circuit according to claim 2, wherein N series resistors are set in sequence as R 1 、R 2 、……、R n , and after the node is connected to the resistor in parallel, 1, 2, and N are set in sequence; one end of the first wire is connected to the common path of the multiplexer, and the other end of the first wire is connected to the connection node 1; The second wire is set up as S 1 、S 2 、……、S n-1 in proper order with the switch as the reference numeral, wherein, one end of S 1 is connected to a branch road of multiplexer, and its other end is connected to connected node 2, and in this order, the other end of S 2 is connected to connected node 3, and the other end of S n-1 is connected to connected node n.
  7. 7. The variable gain transimpedance amplifier circuit of claim 6, wherein n is greater than or equal to 2 and is a positive integer.
  8. 8. The variable gain transimpedance amplifier circuit of claim 6, wherein the resistances of resistors R 1 、R 2 、……、R n are the same or different.
  9. 9. A variable gain transimpedance amplifier circuit according to claim 1, wherein the photoelectric conversion element comprises a PD photodetector.
  10. 10. The variable gain transimpedance amplifier circuit according to claim 1, further comprising a capacitor C 1 , wherein the capacitor C 1 is connected in parallel with the operational amplifier.

Description

Gain-variable type variable gain device transimpedance amplifier circuit Technical Field The invention relates to the technical field of optical communication, in particular to a variable gain transimpedance amplifier circuit. Background In the field of optical communication technology, in order to monitor optical power, a photosensitive element is often used to convert light into energy, such as a photodiode based on a photoelectric effect, so as to convert the light into other energy for detection, such as an electrical signal or other signals, so as to further realize detection of the optical power. As in the prior art CN111835293B, a multi-transimpedance constant bandwidth ultra-low noise TIA is provided, which is applied to the field of chip design. The key point is that the TIA bandwidth is constant under 2 transimpedance, and the resistors are connected in parallel, so that the transimpedance is changed. The application scene is mainly applied to high-bandwidth TIA, and has limitation when the transimpedance range is larger, so that the wider-range optical power detection cannot be compatible, and the flexibility is weaker; As in the prior art CN218335966U, a transimpedance amplifier with variable gain and constant bandwidth is also provided and is applied to the field of chip design. The design of constant TIA bandwidth under 2 transimpedance is also focused on, and the detection of micro-large-range optical power is difficult. Disclosure of Invention Aiming at the technical problems that the optical power detection in the prior art is difficult to realize large-transimpedance design or the cost of integrating a multi-transimpedance circuit in a chip is high, the invention provides a transimpedance amplifier circuit with variable gain, which at least has the advantages of wide detection coverage, flexible adjustment, low adjustment power consumption, low cost, simple and reliable structure and the like. The invention provides a variable gain transimpedance amplifier circuit, comprising: the photoelectric conversion element is arranged in front of the current input node; the operational amplifier is arranged between the current input node and the voltage output node; the transimpedance component is arranged in parallel with the operational amplifier and comprises n resistors arranged in series; And the bypass component is used for controlling the bypass of 1-n-1 resistors of the transimpedance component. Specifically, the main idea of the invention is to utilize the design of the bypass component to realize the adjustment of the whole resistance value of the transimpedance component, thereby enlarging the adjustable range of the resistance value of the transimpedance component, further realizing the wide variable gain of the transimpedance and being suitable for large-range optical power detection. Meanwhile, the invention further contemplates that the series resistance of the transimpedance component is bypassed by the design of the bypass component, so that the minimum resistance value of one resistance of the transimpedance component in the resistance adjustment range is equal to the sum of the resistance values of all the resistances, and the optical power detection can be infinitely small or infinitely large in theory, and the bypass design of the bypass component is beneficial, so that the variable gain adjustment of the transimpedance component is more convenient and reliable. Further, the bypass component comprises a multiplexer with n-1 paths, 1 first wire without a switch and n-1 second wires with a switch; One end of the first wire is connected to the common path of the multiplexer, the other end is connected to the connection node of any resistor, one end of the n-1 second wires is respectively connected with n-1 branches of the multiplexer, and the other ends are respectively connected to the other n-1 connection nodes of the transimpedance assembly. Specifically, the present invention further contemplates that the multiplexer is matched with the first wire and the second wire to realize the bypass function of the bypass assembly, so that the structural design of the bypass assembly is simplified, and the structure of the present invention is better and the power loss is smaller. Further, the multiplexer includes an EN pin and an ADDR address pin; when the EN pin acquires a low level, the switches of the n-1 branches are controlled to be disconnected; when the pin EN acquires high level, the ADDR address pin selects any one of the switches of the corresponding branch circuits to be closed. Specifically, the invention realizes the control of opening and closing any one of the second wires through the address function of the ADDR address pin, thereby simplifying the control logic of the switch and reducing the control power consumption of the second wires. Further, the multiplexer comprises an MCU element. Specifically, the MCU element refers to a small computer chip for outputting a high