Variable gain transimpedance amplifier circuit

Abstract

The invention particularly relates to a trans-impedance amplifier circuit with variable gain. The trans-impedance amplifier circuit comprises a photoelectric conversion element, an operational amplifier, a trans-impedance component and a bypass component, by means of the design of the bypass assembly, the overall resistance value of the transimpedance assembly is adjusted, so that the adjustable range of the resistance value of the transimpedance assembly is enlarged, the wide variable gain of transimpedance is achieved, and the optical power detection device is suitable for large-range optical power detection. Meanwhile, by means of the design of the bypass assembly, the series resistors of the transimpedance assembly are bypassed, so that the resistance value of the minimum resistor in the resistance adjusting range of the transimpedance assembly reaches the sum of the resistance values of all the resistors, and the optical power detection can be infinitely small or infinitely large theoretically. Moreover, due to the bypass design of the bypass assembly, the variable gain adjustment of the transimpedance assembly is more flexible and reliable.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and more specifically to a variable gain transimpedance amplifier circuit. Background Technology

[0002] In the field of optical communication technology, in order to monitor optical power, photosensitive elements are often used to convert light energy, such as photodiodes based on the photoelectric effect, to convert light into other detectable energies, such as electrical signals or other signals, thereby realizing the detection of optical power.

[0003] For example, the existing technology CN111835293B provides a multi-transimpedance constant bandwidth ultra-low noise TIA for chip design. Its key feature is achieving constant TIA bandwidth under two different transimpedances, with resistors connected in parallel to change the transimpedance. This application scenario is mainly used for high-bandwidth TIAs, but it has limitations when the transimpedance range is larger, failing to be compatible with a wider range of optical power detection and exhibiting limited flexibility.

[0004] Existing technology CN218335966U also provides a transimpedance amplifier with variable gain and constant bandwidth, applicable to chip design. It also addresses the design of constant TIA bandwidth under two different transimpedance conditions, which makes it difficult to detect optical power over a small to a large range. Summary of the Invention

[0005] This invention addresses the technical problems in existing technologies where it is difficult to achieve a large transimpedance design for optical power detection or where the cost of integrating multiple transimpedance circuits into chips is high. It provides a variable gain transimpedance amplifier circuit, which has advantages such as wide detection coverage, flexible adjustment, low power consumption, low cost, and simple and reliable structure.

[0006] This invention provides a variable gain transimpedance amplifier circuit, comprising:

[0007] The photoelectric conversion element is positioned before the current input node;

[0008] An operational amplifier is positioned between the current input node and the voltage output node;

[0009] A transimpedance component, connected in parallel to the operational amplifier, includes n resistors connected in series.

[0010] A bypass component is used to control the bypassing of 1 to n-1 resistors of the transresistance component.

[0011] Specifically, the main concept of this invention lies in utilizing the design of the bypass component to adjust the overall resistance value of the transimpedance component, thereby increasing the adjustable range of the transimpedance component's resistance value and achieving a wide range of variable gain, thus making it suitable for large-scale optical power detection. Furthermore, the invention further utilizes the bypass component design to bypass the series resistance of the transimpedance component, allowing the resistance adjustment range of the transimpedance component to range from the smallest single resistor value to the sum of the resistance values ​​of all resistors. Theoretically, this allows for optical power detection that can be infinitely small or infinitely large. Moreover, thanks to the bypass design of the bypass component, the variable gain adjustment of the transimpedance component is more convenient and reliable.

[0012] Furthermore, the bypass component includes a multiplexer with n-1 channels, a first wire without a switch, and n-1 second wires with switches.

[0013] A connection node is provided before or after any resistor of the transimpedance component; wherein, one end of the first wire is connected to the common path of the multiplexer, and the other end is connected to the connection node of any resistor; one end of each of the n-1 second wires is connected to one of the n-1 branches of the multiplexer, and the other end is connected to the other n-1 connection nodes of the transimpedance component.

[0014] Specifically, another concept of the present invention is to utilize the cooperation between the multiplexer and the first and second conductors to realize the bypass function of the bypass component, thereby simplifying the structural design of the bypass component and making the structure of the present invention more superior and with less power loss.

[0015] Furthermore, the multiplexer includes an EN pin and an ADDR address pin;

[0016] When the EN pin receives a low level, the switches of all n-1 branches are turned off;

[0017] When the EN pin receives a high level, the switch of the branch corresponding to any address selected by the ADDR address pin is closed.

[0018] Specifically, the present invention uses the address function of the ADDR address pin to control the opening and closing of any of the second wires, thereby simplifying the control logic of the switch and reducing the control power consumption of the second wires.

[0019] Furthermore, the multiplexer includes an MCU element.

[0020] Specifically, an MCU component refers to a small computer chip used to output a high or low level based on the optical power of the signal light obtained by the photoelectric conversion element.

[0021] Optionally, the drive controller can also be external, that is, the photoelectric conversion element, operational amplifier, transimpedance component and bypass component are constructed as a whole, and the bypass function of the bypass component is controlled by an external drive controller.

[0022] Furthermore, when the output of the drive controller is high, an address will be assigned to the ADDR address pin according to the magnitude of the optical power.

[0023] In some embodiments, the n resistors connected in series are named R1, R2, ..., R... n The connection nodes are then placed after the resistor, in the order of 1, 2, ..., N;

[0024] One end of the first conductor is connected to the common path of the multiplexer, and the other end is connected to connection node 1;

[0025] The second conductors are sequentially labeled S1, S2, ..., S, using switches as their designations. n-1 Wherein, one end of S1 is connected to a branch of the multiplexer, and the other end is connected to connection node 2, and so on, the other end of S2 is connected to connection node 3, ..., S n-1 The other end is connected to the connection node n.

[0026] Specifically, the above embodiments provide an orderly construction method for the bypass component, and the bypass component can also be constructed through other connection methods.

[0027] Optional, n≥2, and takes the form of a positive integer.

[0028] Optional, resistors R1, R2, ..., R n The resistance values ​​may be the same or not exactly the same.

[0029] In some embodiments, the photoelectric conversion element includes a PD photodetector.

[0030] In some embodiments, the transimpedance amplifier circuit further includes a capacitor C1, which is connected in parallel with the operational amplifier.

[0031] Specifically, the capacitor C1 is used to improve the stability of the system and prevent damage to the circuit caused by high-power signal light when the resistance of the transimpedance component is small or changes significantly, or when an unsuitable resistance value is selected. This improves the stability and structural reliability of the transimpedance amplifier circuit provided by the present invention.

[0032] In summary, the present invention provides a variable gain transimpedance amplifier circuit, which has at least the following advantages:

[0033] 1. This invention utilizes a bypass component design to adjust the overall resistance value of the transimpedance component, thereby increasing the adjustable range of the transimpedance component's resistance and achieving a wide range of variable gain, making it suitable for large-scale optical power detection. Furthermore, this invention, through the bypass component design, bypasses the series resistance of the transimpedance component, allowing the resistance adjustment range to extend from the smallest single resistor value to the sum of the resistance values ​​of all resistors. Theoretically, this invention can detect optical power at infinitely small or infinitely large values. Moreover, thanks to the bypass design of the bypass component, the variable gain adjustment of the transimpedance component is more convenient and reliable.

[0034] 2. The present invention also utilizes the cooperation of the multiplexer with the first and second conductors to realize the bypass function of the bypass component, thereby simplifying the structural design of the bypass component and making the structure of the present invention more superior and with less power loss.

[0035] 3. The present invention also improves the stability of the system by setting capacitor C1, so as to avoid damage to the circuit caused by high-power signal light when the resistance value of the transimpedance component is small or the resistance value changes greatly or an unsuitable resistance value is selected, thereby improving the stability and structural reliability of the transimpedance amplifier circuit provided by the present invention. Attached Figure Description

[0036] The present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be construed as limiting the scope of the invention. Furthermore, unless specifically indicated, the drawings are only schematic representations of the composition or structure of the described objects and may contain exaggerated depictions, and the drawings are not necessarily drawn to scale.

[0037] Figure 1 A schematic diagram of a variable gain transimpedance amplifier circuit provided in one embodiment of the present invention;

[0038] Figure 2 A schematic diagram of the circuit structure of a variable gain transimpedance amplifier circuit provided in another embodiment of the present invention;

[0039] Figure 3 A schematic diagram of the circuit structure of a 4-way multiplexer with a connection node at the end, provided in an embodiment of the present invention. Detailed Implementation

[0040] The following is in conjunction with the appendix Figures 1 to 3 The present invention will be described in detail below.

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] It is worth noting that the use of ordinal numbers such as "first" and "second" in the embodiments of the present invention is for distinguishing multiple objects, and is not for limiting the order, sequence, priority, or importance of multiple objects. For example, "first wire" and "second wire" are only for ease of description, and do not indicate any difference in the order or importance of "first wire" and "second wire".

[0043] Furthermore, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, a mating connection, or an integral connection; it can also be a direct connection or an indirect connection. For those skilled in the art, unless otherwise specified, "connection" in the embodiments provided by this invention should be understood as an electrical connection.

[0044] The main concept of this invention is to use the bypass function of the bypass component to adjust the gain resistance of the transimpedance component, thereby achieving the detection of optical power over an extremely high range.

[0045] For an explanation of the composition of this invention, please refer to [link / reference]. Figure 1 The diagram shown is a schematic representation of a variable gain transimpedance amplifier circuit according to an embodiment of the present invention.

[0046] Specifically, the transimpedance amplifier circuit provided by this invention includes a photoelectric conversion element, an operational amplifier, a transimpedance component, and a bypass component. The photoelectric conversion element receives signal light and provides an output current for detection based on the light power intensity. The operational amplifier converts the output current provided by the photoelectric conversion element into a voltage based on the resistance value of the transimpedance component. By calculating the correspondence between voltage and light power, the optical power of the signal light is detected. Since the transimpedance component consists of multiple resistors connected in series, the bypass component can selectively bypass different numbers of resistors, thereby changing the resistance value provided by the transimpedance component. This allows the operational amplifier to obtain different resistance gains, thus enabling the invention to measure light power in different ranges.

[0047] It is worth understanding that current input nodes and voltage output nodes theoretically do not exist. However, in the connection process of real circuits, different components need adjacent wires to achieve interconnection, thus forming series or parallel relationships between electronic devices. Consequently, there are actual nodes where wires are interconnected. Therefore, to explain the inventive concept, this invention uses current input nodes and voltage output nodes to represent the conversion of signal energy. Figure 1 The Input in the diagram refers to the current input node, where the output current generated by the photoelectric conversion element based on the photoelectric effect enters the current input node and is used by the operational amplifier for gain amplification. Correspondingly, the Output is the voltage output node, where the voltage is output after amplification and conversion by the operational amplifier. This allows the optical power detection instrument to obtain the optical power intensity of the signal light based on the magnitude of the voltage output by connecting to the voltage output node.

[0048] further, Figure 2 Another embodiment of the present invention provides a schematic diagram of the circuit structure of a variable gain transimpedance amplifier circuit. Figure 2 A transimpedance amplifier circuit is implemented by connecting specific electrical components.

[0049] Specifically, the preferred photoelectric conversion element in this invention is a PD photodetector. The PD photodetector converts the optical signal of the signal light into an electrical signal after the photoelectric effect, i.e., I shown in the figure. PD I PD The voltage output Vout is obtained by amplifying the signal through an Amp operational amplifier and a transimpedance component connected in parallel with the Amp operational amplifier. That is, Vout = A * I. PD A represents the gain of the Amp operational amplifier, which is the resistance value provided by the transimpedance component.

[0050] The transresistance component consists of R1, R2, ..., R n The system consists of n resistors connected in series, where n is a positive integer ≥ 2. To achieve different resistance gains, the transimpedance component uses a bypass component to select different numbers of resistors for bypassing, thus providing transimpedance resistors of different values ​​for the Amp operational amplifier. The bypass component includes a multiplexer with n-1 channels, a first wire without a switch, and n-1 second wires with switches. One end of the first wire is connected to the common path D of the multiplexer, and the other end is connected to connection node 1. One end of the second wire S1 is connected to a branch path of the multiplexer, and the other end is connected to connection node 2. Switch S1 controls the conduction of the second wire S1. One end of the second wire S2 is connected to a branch path of the multiplexer, and the other end is connected to connection node 3. Switch S2 controls the conduction of the second wire S2, and so on. n-1One end is connected to a branch of the multiplexer, and the other end is connected to connection node n. Switch S n-1 Used to control the second wire S n-1 The conduction of the switch allows the present invention to be controlled by switching S1 to S2. n-1 By closing any switch or opening all switches, different transimpedance values ​​can be obtained, thereby enabling the Amp operational amplifier to obtain different resistance gains and achieve the function of measuring optical power within different ranges. Furthermore, Figure 2 The connection point was chosen to be after the resistor.

[0051] To illustrate the resistance values ​​obtained under different switch opening and closing conditions, please refer to Table 1, which is a summary table of transresistance control.

[0052] Table 1. Overview of Transresistance Size Control

[0053]

[0054] When all switches are open, all resistors in the transresistance assembly are connected in series, and the resistance provided by the transresistance assembly is R1 + R2 + R3 + ... + R n When switch S1 is closed and other switches are open, resistor R2 is bypassed, and the resistance provided by the transresistance component is R1 + R3 + ... + R n When switch S2 is closed and other switches are open, resistors R2 and R3 are bypassed, and the resistance provided by the transresistance assembly is R1 + ... + R n ; and so on, when switch S n-1 When closed and other switches open, resistors R2 to R n The bypass component provides a resistance value of R1. Through the above control process, the bypass component bypasses 1 to n-1 resistors in the transimpedance component, thereby providing variable gain for the operational amplifier with different resistance values. It is worth noting that R1, R2, R3, ..., R... n The resistance values ​​can be the same or different, mainly depending on the accuracy and range of the optical power detection.

[0055] Furthermore, the multiplexer provided by this invention uses EN pins and ADDR address pins to control the closing of switches within the multiplexer. Figure 2 The multiplexer, referred to as a multiplexer, receives Enable and Logic Signals (high / low level signals and address logic signals) through an externally provided driver. When Enable receives a low-level signal, it controls all switches S1 to S2. n-1When the Enable signal is high, the Logic Signals provide an address signal to control switches S1 to S2. n-1 The closing of a certain switch.

[0056] Furthermore, the multiplexer includes a drive controller that receives the Enable signal and the LogicSignals signal as inputs.

[0057] Furthermore, the drive controller is equipped with at least S1 to S2. n-1 Each address corresponds to a switch, thus allowing control of any switch in the multiplexer by selecting the address.

[0058] Furthermore, the drive controller is connected to the photoelectric conversion element or receives the signal light through a photosensitive device, so that the drive controller can control the multiplexer according to the optical power intensity of the signal light.

[0059] To further explain the technical solution provided by this invention, a 4-channel multiplexer is used as an example to illustrate its working principle. In this example, the invention includes five resistors: R1, R2, R3, R4, and R5; one first conductor; four second conductors: S1, S2, S3, S4, and S5; and five connection nodes: 1, 2, 3, 4, and 5. It is understood that the multiplexer can also have 8, 16, or even 5, 12, or other numbers of channels. When selecting other numbers of channels, the 4-channel multiplexer can be used for reference.

[0060] Example

[0061] For details, please see Figure 3 The diagram shows a circuit structure of a 4-way multiplexer with subsequent connection nodes provided in an embodiment of the present invention. In this case, each connection node is located after a resistor; that is, connection node 1 is located after resistor R1, connection node 2 is located after resistor R2, ..., connection node 5 is located after resistor R5. One end of the first wire is connected to connection node 1, and the other end is connected to the common path D of the multiplexer. One end of the second wire S1 is connected to connection node 2, and the other end is connected to a branch path of the multiplexer. One end of the second wire S2 is connected to connection node 3, and the other end is connected to a branch path of the multiplexer. One end of the second wire S3 is connected to connection node 4, and the other end is connected to a branch path of the multiplexer. One end of the second wire S4 is connected to connection node 5, and the other end is connected to a branch path of the multiplexer.

[0062] The operation of the transimpedance amplifier circuit provided by this invention will be divided into the following 5 scenarios:

[0063] The EN pin receives a low-level signal from Enable. At this time, all switches are open, and the resistors on the transimpedance component are connected in series in sequence. The resistance value R is R1+R2+R3+R4+R5. At this time, the gain of the transimpedance amplifier circuit is at its maximum.

[0064] The EN pin receives a high-level signal from Enable. The ADDR address pin controls the closing of a switch according to the logic address. When the closed switch is S1, the first wire and the second wire S1 are connected, that is, the connection between node 1 and node 2 is connected, and the resistor R2 is bypassed, so the resistance value R is R1+R3+R4+R5.

[0065] The EN pin receives a high-level signal from Enable. The ADDR address pin controls the closing of a switch according to the logic address. When the closed switch is S2, the first wire and the second wire S2 are connected, that is, the connection between node 1 and node 3 is connected. Resistors R2 and R3 are bypassed, so the resistance value R is R1+R4+R5.

[0066] The EN pin receives a high-level signal from Enable. The ADDR address pin controls the closing of a switch according to the logic address. When the closed switch is S3, the first wire and the second wire S3 are connected, that is, the connection between node 1 and node 4 is connected. Resistors R2, R3 and R4 are bypassed, so the resistance value R is R1+R5.

[0067] The EN pin receives a high-level Enable signal. The ADDR address pin controls the closing of a switch according to the logic address. When the closed switch is S4, the first wire and the second wire S4 are connected, that is, the connection between node 1 and node 5 is connected. Resistors R2, R3, R4 and R5 are bypassed, so the resistance value R is R1. At this time, the gain of the transimpedance amplifier is the minimum.

[0068] According to the embodiments provided by the present invention, the connection node can also be placed before the resistor, which will also yield five different resistance gains. Furthermore, according to the embodiments provided by the present invention, the connection node of the first wire can also be placed before or after any resistor, similarly yielding five different resistance gains.

[0069] In summary, changing the position of the connection node before and after the resistor and the position of the connection node of the first wire does not change the number of cases in which the resistance gain is provided, thus allowing for a variety of possible embodiments of the present invention.

[0070] also, Figure 3 The capacitor C1, which is connected in parallel with the Amp operational amplifier, is used to ensure the stability of the system. Due to the large range of resistance changes, large fluctuations in current and voltage are easily generated. In order to ensure that the circuit structure is not damaged, capacitor C1 can play a temporary protection role.

[0071] The present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of the embodiments above are only for the purpose of helping to understand the invention and its core ideas. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A variable gain transimpedance amplifier circuit, characterized in that, include: The photoelectric conversion element is positioned before the current input node; An operational amplifier is positioned between the current input node and the voltage output node; A transimpedance component, connected in parallel to the operational amplifier, includes n resistors connected in series. A bypass component is used to control the bypassing of 1 to n-1 resistors of the transresistance component.

2. The variable gain transimpedance amplifier circuit as described in claim 1, characterized in that, The bypass component includes a multiplexer with n-1 channels, a first wire without a switch, and n-1 second wires with switches; A connection node is provided before or after any resistor of the transimpedance component; wherein, one end of the first wire is connected to the common path of the multiplexer, and the other end is connected to the connection node at any resistor; one end of each of the n-1 second wires is connected to one of the n-1 branches of the multiplexer, and the other end is connected to the other n-1 connection nodes of the transimpedance component.

3. The variable gain transimpedance amplifier circuit as described in claim 2, characterized in that, The multiplexer includes an EN pin and an ADDR address pin; When the EN pin receives a low level, the switches of all n-1 branches are turned off; When the EN pin receives a high level, the switch of the branch corresponding to any address selected by the ADDR address pin is closed.

4. The variable gain transimpedance amplifier circuit as described in claim 3, characterized in that, The multiplexer includes MCU components.

5. The variable gain transimpedance amplifier circuit as described in claim 4, characterized in that, When the output of the drive controller is high, an address will be assigned to the ADDR address pin according to the magnitude of the optical power.

6. A variable gain transimpedance amplifier circuit as described in claim 2, characterized in that, ... The n resistors connected in series are R1, R2, ..., R... n The connection nodes are then placed after the resistor, in the order of 1, 2, ..., N; One end of the first conductor is connected to the common path of the multiplexer, and the other end is connected to connection node 1; The second conductors are sequentially labeled S1, S2, ..., S, using switches as their designations. n-1 Wherein, one end of S1 is connected to a branch of the multiplexer, and the other end is connected to connection node 2, and so on, the other end of S2 is connected to connection node 3, ..., S n-1 The other end is connected to the connection node n.

7. A variable gain transimpedance amplifier circuit as described in claim 6, characterized in that, n≥2 and takes a positive integer.

8. A variable gain transimpedance amplifier circuit as described in claim 6, characterized in that, Resistors R1, R2, ..., R n The resistance values ​​may be the same or not exactly the same.

9. A variable gain transimpedance amplifier circuit as described in claim 1, characterized in that, The photoelectric conversion element includes a PD photodetector.

10. A variable gain transimpedance amplifier circuit as described in claim 1, characterized in that, The transimpedance amplifier circuit also includes a capacitor C1, which is connected in parallel with the operational amplifier.

Images