阅读说明：本技术 一种光电放大电路 (Photoelectric amplification circuit ) 是由 张研 张浩然 于 2021-02-23 设计创作，主要内容包括：本发明公开了一种光电放大电路。该光电放大电路,包括：放大器、第一电阻、至少两个第一晶体管和电流控制模块,所述第一电阻连接于所述放大器的第一输入端和输出端之间,所述放大器的第一输入端连接有光电二极管,所述放大器的第二输入端连接参考电压；各所述第一晶体管并联于第一电源和所述放大器的第一输入端之间；各所述第一晶体管的沟道宽长比不同；连接所述第一电阻的两端以及分别连接各所述第一晶体管的栅极,用于根据所述第一电阻两端的电压,控制开启至少一个所述第一晶体管,后开启的所述第一晶体管的沟道宽长比大于先开启的所述第一晶体管的沟道宽长比。本发明公开的一种光电放大电路,实现了高灵敏度、强抗干扰能力和高信噪比的效果。(The invention discloses a photoelectric amplifying circuit. The photoelectric amplification circuit comprises: the current control circuit comprises an amplifier, a first resistor, at least two first transistors and a current control module, wherein the first resistor is connected between a first input end and an output end of the amplifier, the first input end of the amplifier is connected with a photodiode, and a second input end of the amplifier is connected with a reference voltage; each first transistor is connected in parallel between a first power supply and the first input end of the amplifier; the channel width-length ratio of each first transistor is different; the first transistor is connected with the two ends of the first resistor and the grid of each first transistor respectively, and the first transistor is controlled to be turned on according to the voltage at the two ends of the first resistor, and the channel width-length ratio of the first transistor which is turned on later is larger than the channel width-length ratio of the first transistor which is turned on first. The photoelectric amplifying circuit disclosed by the invention realizes the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio.)

1. A photoelectric amplification circuit, comprising:

the first resistor is connected between a first input end and an output end of the amplifier, the first input end of the amplifier is connected with a photodiode, and a second input end of the amplifier is connected with a reference voltage;

at least two first transistors, each of the first transistors being connected in parallel between a first power supply and a first input terminal of the amplifier; the channel width-length ratio of each first transistor is different;

and the current control module is connected with two ends of the first resistor and the grid electrodes of the first transistors respectively, and is used for controlling to turn on at least one first transistor according to the voltage at two ends of the first resistor, wherein the channel width-length ratio of the first transistor which is turned on later is larger than the channel width-length ratio of the first transistor which is turned on earlier.

2. The photoelectric amplification circuit of claim 1, wherein the current control module comprises: the first input end of the differential amplifier is connected with the first input end of the amplifier, and the second input end of the differential amplifier is connected with the output end of the amplifier; the output end of the differential amplifier is connected with the control circuit, the control circuit is controlled by the differential amplifier and is used for controlling at least one first transistor to be started, and the channel width-length ratio of the first transistor which is started later is larger than that of the first transistor which is started first.

3. The photoelectric amplification circuit according to claim 1, wherein the number of the first transistors is 2, and each of the first transistors is a P-type transistor.

4. The photoelectric amplification circuit according to claim 3, wherein the control circuit comprises: the first P type transistor, the second P type transistor, the first N type transistor, the second N type transistor, the third N type transistor and the second resistor;

the transistor with the smaller channel width and length ratio is used as a third P-type transistor, and the transistor with the larger channel width and length ratio is used as a fourth P-type transistor;

the connection point of the second resistor and the drain electrode of the third N-type transistor is a first connection point;

wherein a first output terminal and a second output terminal of the differential amplifier are respectively connected with a source electrode of the second P-type transistor and a source electrode of the first P-type transistor, the drains of the first N-type transistor and the second N-type transistor are respectively connected with the drains of the first P-type transistor and the second P-type transistor, the second resistor is connected between the drain of the third N-type transistor and the first power supply, the grid electrode and the drain electrode of the first P-type transistor are short-circuited, the drain electrode and the grid electrode of the second N-type transistor are short-circuited, the grid electrode of the first P-type transistor, the grid electrode of the second P-type transistor and the grid electrode of the third P-type transistor are connected in sequence, the grid electrode of the first N-type transistor, the grid electrode of the second N-type transistor and the grid electrode of the third N-type transistor are sequentially connected, and the first connecting point is connected with the grid electrode of the fourth P-type transistor.

5. The photoelectric amplification circuit according to claim 4, wherein a direct current flowing through the photodiode is not greater than a saturation region current of a third P-type transistor, a difference between the voltage of the first power supply and the first connection point voltage is smaller than a threshold voltage of a fourth P-type transistor, the third P-type transistor is turned on, and the fourth P-type transistor is turned off.

6. The photoelectric amplification circuit according to claim 4, wherein a direct current flowing through the photodiode is larger than a saturation region current of a third P-type transistor, a difference between the voltage of the first power supply and the first connection point voltage is larger than a threshold voltage of a fourth P-type transistor, and the third P-type transistor and the fourth P-type transistor are both turned on.

7. The photo-electric amplification circuit of claim 2, wherein the bandwidth of the differential amplifier is less than the frequency of the alternating current flowing through the photodiode.

8. The photoelectric amplification circuit of claim 4, wherein the current control module further comprises: the first capacitor is connected between a first output end and a grounding end of the differential amplifier, the second capacitor is connected between a second output end and the grounding end of the differential amplifier, one end of the third capacitor is connected between a grid electrode of the first P-type transistor and the first power supply, one end of the fourth capacitor is connected between the first connecting point and the first power supply, and the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are all used for reducing the output bandwidth of the differential amplifier.

Technical Field

The embodiment of the invention relates to a photoelectric technology, in particular to a photoelectric amplifying circuit.

Background

The photoelectric amplifier is a key device of the photoelectric sensor, realizes the function of converting optical signals into electric signals, and directly determines the performance index of the sensor through the sensitivity and the anti-interference capability of ambient light.

A conventional photoelectric amplifying circuit adopts a transimpedance amplifier structure as shown in fig. 1, and if there is interference of external ambient light, the structure is generally embodied as a direct current signal in the circuit, and the direct current signal can directly flow through a resistor R_fThereby causing a serious decrease in the gain of the amplifier and lowering the reception sensitivity.

In order to solve the above problems, an improved photoelectric amplifying circuit as shown in fig. 2 is proposed, but the adoption of such a circuit cannot completely prevent the interference current from flowing over the feedback resistor of the amplifying circuit under the condition of strong interference, and the circuit also causes the input signal to flow through the bypass, thereby reducing the signal-to-noise ratio and the sensitivity.

Disclosure of Invention

The invention provides a photoelectric amplifying circuit, which is used for realizing the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio.

An embodiment of the present invention provides a photoelectric amplification circuit, including: the circuit comprises an amplifier, a first resistor, at least two first transistors and a current control module; the first resistor is connected between a first input end and an output end of the amplifier, the first input end of the amplifier is connected with a photodiode, and a second input end of the amplifier is connected with a reference voltage; each first transistor is connected in parallel between a first power supply and the first input end of the amplifier; the channel width-length ratio of each first transistor is different; the first transistor is connected with the two ends of the first resistor and the grid of each first transistor respectively, and the first transistor is controlled to be turned on according to the voltage at the two ends of the first resistor, and the channel width-length ratio of the first transistor which is turned on later is larger than the channel width-length ratio of the first transistor which is turned on first.

Optionally, the current control module further comprises: the first input end of the differential amplifier is connected with the first input end of the amplifier, and the second input end of the differential amplifier is connected with the output end of the amplifier; the output end of the differential amplifier is connected with the control circuit, the control circuit is controlled by the differential amplifier and is used for controlling at least one first transistor to be started, and the channel width-length ratio of the first transistor which is started later is larger than that of the first transistor which is started first.

Optionally, the number of the first transistors is 2, and each of the first transistors is a P-type transistor.

Optionally, the control circuit comprises: the first P type transistor, the second P type transistor, the first N type transistor, the second N type transistor, the third N type transistor and the second resistor; the transistor with the smaller channel width and length ratio is used as a third P-type transistor, and the transistor with the larger channel width and length ratio is used as a fourth P-type transistor; the connection point of the second resistor and the drain electrode of the third N-type transistor is a first connection point; wherein a first output terminal and a second output terminal of the differential amplifier are respectively connected with a source electrode of the second P-type transistor and a source electrode of the first P-type transistor, the drains of the first N-type transistor and the second N-type transistor are respectively connected with the drains of the first P-type transistor and the second P-type transistor, the second resistor is connected between the drain of the third N-type transistor and the first power supply, the grid electrode and the drain electrode of the first P-type transistor are short-circuited, the drain electrode and the grid electrode of the second N-type transistor are short-circuited, the grid electrode of the first P-type transistor, the grid electrode of the second P-type transistor and the grid electrode of the third P-type transistor are connected in sequence, the grid electrode of the first N-type transistor, the grid electrode of the second N-type transistor and the grid electrode of the third N-type transistor are sequentially connected, and the first connecting point is connected with the grid electrode of the fourth P-type transistor.

Optionally, a direct current flowing through the photodiode is not greater than a saturation region current of a third P-type transistor, a difference between a voltage of the first power supply and a voltage of the first connection point is smaller than a threshold voltage of a fourth P-type transistor, the third P-type transistor is turned on, and the fourth P-type transistor is turned off.

Optionally, a direct current flowing through the photodiode is greater than a saturation region current of a third P-type transistor, a difference between a voltage of the first power supply and a voltage of the first connection point is greater than a threshold voltage of a fourth P-type transistor, and the third P-type transistor and the fourth P-type transistor are both turned on.

Optionally, the bandwidth of the differential amplifier is less than the frequency of the alternating current flowing through the photo amplifier.

Optionally, the current control module further comprises: the first capacitor is connected between a first output end and a grounding end of the differential amplifier, the second capacitor is connected between a second output end and the grounding end of the differential amplifier, one end of the third capacitor is connected between a grid electrode of the first P-type transistor and the first power supply, one end of the fourth capacitor is connected between the first connecting point and the first power supply, and the first capacitor, the second capacitor, the third capacitor and the fourth capacitor are all used for reducing the output bandwidth of the differential amplifier.

The embodiment of the invention provides a photoelectric amplification circuit, wherein a current control module gradually turns on a certain number of first transistors according to the change of direct current signals at two ends of a feedback resistor of an amplifier, so that a sufficiently large path is provided for direct current generated by a photodiode, and the resistance of the path is relatively large, so that the photoelectric amplification circuit is suitable for interference sources with different intensities, the circuit can resist direct current interference and simultaneously ensure minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

Drawings

Fig. 1 is a conventional photoelectric amplifying circuit in the prior art;

FIG. 2 is another improved prior art electro-optic amplification circuit;

fig. 3 is a schematic diagram of an optoelectronic amplifying circuit according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of another photoelectric amplifying circuit according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a further photoelectric amplifying circuit according to an embodiment of the present invention;

fig. 6 is a circuit diagram of a further photoelectric amplifying circuit according to an embodiment of the present invention;

fig. 7 is a circuit diagram of another photoelectric amplification circuit according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

An embodiment of the present invention provides a photoelectric amplification circuit 100, fig. 3 is a schematic diagram of the photoelectric amplification circuit 100 according to the embodiment of the present invention, and referring to fig. 3, the photoelectric amplification circuit 100 includes: amplifier 101, first resistor R_fAt least two first transistors 102 and a current control module 103; a first resistor R_fConnected between a first input terminal and an output terminal of the amplifier 101, the first input terminal of the amplifier 101 is connected to the photodiode 107, and a second input terminal of the amplifier 101 is connected to the reference voltage V_ref(ii) a Each first transistor 102 is connected in parallel to a first power supply V_DDAnd a first input of amplifier 101; the channel width-to-length ratios of the first transistors 102 are different; the current control module 103 is connected with a first resistor R_fAnd a gate connected to each first transistor 102, respectively, for receiving a first resistance R_fThe voltage across the two terminals controls to turn on at least one first transistor 102, and the channel width-to-length ratio of the first transistor 102 which is turned on later is larger than the channel width-to-length ratio of the first transistor 102 which is turned on first.

Wherein the output terminal voltage of the amplifier 101 is the output signal V of the amplifying circuit_out(ii) a The photodiode 107 is used to convert the optical signal into a current signal, and the photodiode 107 can convert the modulated light source into an alternating current signal of a specific frequency under the environment without interference of the light sourceNumber; amplifier 101 and first resistor R_fFor converting the current signal emitted by the photodiode 107 into a voltage signal V at the output of the amplifier 101_outThe magnitude of the voltage signal at the output of the amplifier 101 and the first resistor R_fThe resistance values of (A) and (B) are in positive correlation; the current control module 103 is based on a first resistance R_fThe direct current signals at the two ends control the gradual opening of the first transistor 102; the sum of the currents of the turned-on first transistor 102 is equal to the direct current I flowing through the photodiode 107₁The first transistor 102 is turned on to generate a DC current I flowing through the photodiode 107₁Providing a low impedance path.

Illustratively, the photodiode 107 is disturbed by ambient light to generate a DC current I₁Before the first transistor 102 is turned on, a direct current I flowing in reverse through the photodiode 107₁Flows through the first resistor R_fThe current control module 103 detects the first resistor R_fThe DC signal at both ends changes, and the transistor with the smallest channel width-length ratio in each first transistor 102 is turned on to obtain DC current I₁Providing a passageway; if the first transistor is turned on, the current control module 103 detects the first resistor R_fDoes not have a dc signal at both ends, and the photodiode 107 generates a dc current I due to the ambient light interference at this time₁Equal to the current flowing through the first transistor 102 that is on; if one transistor is turned on, the current control module 103 detects the first resistor R_fIf there is still a dc signal change at both ends, the transistor with the smallest channel width-to-length ratio in each first transistor 102 in the off state is turned on, and the two turned-on transistors are connected in parallel to the first power supply V_DDAnd the cathode of the photodiode 107, is a direct current I₁Providing a path to pass a greater current; each first transistor 102 is controlled by the current control module 103, and increases with the ambient light interference and the DC current I₁The transistors are turned on in a stepwise manner in order of increasing the channel width-to-length ratio of the first transistors 102.

It should be noted that the formula I is based on the current in the saturation region of the transistor_ds=KW/L*(V_gs-V_t)^2, the current passing through the saturation region of the transistor is in direct proportion to the width-to-length ratio W/L of the transistor channel; by the equivalent resistance of the transistor_o=1/(λ*I_ds) It can be seen that the saturation current of the transistor is inversely related to the equivalent resistance of the transistor; since the noise of the photo-amplifying circuit 100 is inversely related to the equivalent resistance of the dc path, and reducing the noise of the photo-amplifying circuit 100 increases the sensitivity of the circuit, as the channel width-to-length ratio W/L of the transistor increases, the equivalent resistance decreases, and the current through the transistor increases, which is the dc current I₁A better path is provided, but in this process the noise of the photo-electric amplification circuit 100 is increased, i.e. it is contradictory to improve the circuit sensitivity and to improve the anti-interference capability of the circuit. The invention adopts the sectional type step-by-step opening direct current path to well solve the contradiction between the sensitivity and the anti-interference capability, and the transistor for providing current is opened step by step according to the magnitude of direct current generated by ambient light, so that the aim of minimizing noise is realized while the anti-interference capability of the circuit is ensured, and the sensitivity of the photoelectric amplifier is improved.

In the photoelectric amplification circuit 100 according to the embodiment of the present invention, the current control module 103 gradually turns on a certain number of the first transistors 102 according to the change of the dc signals at the two ends of the feedback resistor of the amplifier 101, so as to adapt to the dc signal I generated by the photodiode 107 under different ambient light intensities₁Make a direct current I₁All flow through from first transistor and do not pass through feedback resistance to reach the effect of anti ambient light interference, simultaneously, open first transistor step by step can make bypass resistance reduce step by step, thereby circuit noise also increases step by step, at direct current I₁The circuit noise can be guaranteed to be low under the low condition while resisting interference, the photoelectric amplification circuit 100 is suitable for interference sources with different intensities, the circuit can resist direct current interference while guaranteeing the minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

Fig. 4 is a schematic diagram of another photoelectric amplification circuit 100 according to an embodiment of the present invention, and referring to fig. 4, optionally, the current control module 103 further includes: a differential amplifier 104 and a control circuit 105, wherein a first input end of the differential amplifier 104 is connected with a first input end of the amplifier 101, and a second input end of the differential amplifier 104 is connected with an output end of the amplifier 101; the output end of the differential amplifier 104 is connected to the control circuit 105, and the control circuit 105 is controlled by the differential amplifier 104 and is used for controlling to turn on at least one first transistor 102, wherein the channel width-to-length ratio of the first transistor 102 which is turned on later is larger than the channel width-to-length ratio of the first transistor 102 which is turned on earlier.

The differential amplifier 104 is a dual-input dual-output differential amplifier 104, the bandwidth of the differential amplifier 104 is smaller than the frequency of the alternating current flowing through the photo amplifier 101, the first and second input terminals of the differential amplifier 104 are respectively connected to the first resistor R_fFor collecting the first resistance R_fTwo-terminal DC signal, the differential amplifier 104 collects the first resistor R_fThe dc signals at the two ends output corresponding signals to change the operating state of the control circuit 105, and further control the first transistors 102 to turn on the first transistors 102 step by step according to the sequence of the channel width-length ratio of each first transistor 102 from small to large until the first resistor R_fThere is no dc signal present across.

Illustratively, the photodiode 107 is disturbed by ambient light to generate a DC current I₁Before the first transistor 102 is turned on, the DC current I₁Flows through the first resistor R from right to left_fThen, the dc voltage signal received by the first input terminal of the differential amplifier 104 decreases, the dc voltage signal received by the second input terminal of the differential amplifier 104 decreases, and correspondingly, the output signal of the second input terminal of the differential amplifier 104 increases, the output signal of the first input terminal of the differential amplifier 104 decreases, and the control circuit 105 controls the first transistors 102 to be turned on step by step according to the sequence from the smaller to the larger of the channel width-length ratio of the first transistors 102 according to the signal output by the output terminal of the differential amplifier 104 until the first resistor R reaches the first resistor R_fThere is no dc signal present across.

In the photoelectric amplification circuit 100 provided by the embodiment of the invention, the differential amplifier 104 collects direct current signals at two ends of the feedback resistor, and the control circuit 105 controls the first transistors 102 to be turned on step by step according to the output signal of the differential amplifier 104, in the sequence from small to large of the channel width-to-length ratio of each first transistor 102, so that the photoelectric amplification circuit 100 is suitable for interference sources with different intensities, the circuit can resist direct current interference and simultaneously ensure minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

Fig. 5 is a schematic diagram of another photoelectric amplification circuit 100 according to an embodiment of the present invention, and referring to fig. 5, optionally, the number of the first transistors 102 is 2, and each first transistor 102 is a P-type transistor.

Illustratively, the number of the first transistors 102 is 2, and the channel width-to-length ratio of the first transistors 102 which are turned on later is larger than the channel width-to-length ratio of the first transistors 102 which are turned on first; DC current I generated by ambient light interference at photodiode 107₁When the channel width/length ratio is small, the current in the saturation region of the first transistor 102 is larger than the direct current I₁The first transistor 102 with a small channel width/length ratio is turned on to generate a DC current I₁A path is provided where the current through the first transistor 102 with a small channel width to length ratio is equal to the dc current I₁First resistance R_fNo direct current signal passes through the two ends, and the bypass equivalent resistance is the equivalent resistance of the first transistor 102 with a small channel width-length ratio; the photodiode 107 is interfered by ambient light to generate a DC current I₁When the channel width/length ratio is larger, the current in the saturation region of the first transistor 102 with the smaller channel width/length ratio is smaller than the direct current I₁Then, both the first transistors 102 are turned on to be the DC current I₁A path is provided in which the sum of the currents through the two first transistors 102 equals the direct current I₁First resistance R_fWhen no dc signal passes through the two terminals, the shunt equivalent resistance is the parallel equivalent resistance of the two first transistors 102, and the shunt equivalent resistance is reduced.

The photoelectric amplification circuit 100 provided by the embodiment of the invention can control the first transistor 102 to be turned on step by step according to the magnitude of the environmental interference, so that the direct current interference is resisted, the noise is minimized, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

FIG. 6 shows the present inventionReferring to fig. 6, the circuit diagram of still another photoelectric amplification circuit 100 according to the embodiment optionally includes a control circuit 105, including: a first P type transistor P₁A second P-type transistor P₂A first N-type transistor N₁A second N-type transistor N₂A third N-type transistor N₃And a second resistance R; the third P-type transistor P with a smaller channel width/length ratio in the first transistor 102₃The fourth P-type transistor P of the first transistor 102 with a larger channel width/length ratio₄(ii) a A second resistor and a third N-type transistor N₃The connection point of the drain electrode of (1) is a first connection point M.

Wherein, the first output terminal and the second output terminal of the differential amplifier 104 are respectively connected with the second P-type transistor P₂And a first P-type transistor P₁A first N-type transistor N₁And a second N-type transistor N₂Are respectively connected with the first P-type transistor P₁And a second P-type transistor P₂The second resistor R is connected with the third N-type transistor N₃And a first power supply V_DDFirst P type transistor P₁Is shorted to the drain, and a second N-type transistor N₂Is shorted to the gate, the first P-type transistor P₁A second P-type transistor P₂And a third P-type transistor P₃Are sequentially connected with a first N-type transistor N₁Gate of the second N-type transistor N₂Gate of the third N-type transistor N₃Are connected in sequence, the first connecting point M is connected with the fourth P-type transistor P₄A gate electrode of (1); a first P type transistor P₁A second P-type transistor P₂And a third P-type transistor P₃Form a current mirror Q₁(ii) a A first N-type transistor N₁A second N-type transistor N₂And a third N-type transistor N₃Form a current mirror Q₂。

Illustratively, the photodiode 107 is disturbed by ambient light to generate a DC current I₁Smaller case, the third P-type transistor P₃Current in saturation region of not less than DC current I₁In the third P-type transistor P₃Before openingThe photodiode 107 is interfered by ambient light to generate a DC current I₁Flows through the first resistor R from right to left_fThe first resistor R is collected at the first and second input terminals of the differential amplifier 104_fWhen the DC voltage difference between the two terminals increases, the signal at the first output terminal of the differential amplifier 104 increases, turning on the second P-type transistor P₂Flows through the second P-type transistor P₂Current of (I)₂Will be driven by a current mirror Q₂Is mirrored to the first P-type transistor P₂Since the signal at the second output terminal of the differential amplifier 104 is reduced, a current flows through the first P-type transistor P₁A first P-type transistor P₁The gate voltage of (2) is also reduced due to the current mirror Q₁Thus further turning on the second P-type transistor P₂And the third P-type transistor P is turned on₃Is a direct current I₁Providing a path through the third P-type transistor P₃Has a current of I₃At this time I₃=I₁The bypass equivalent resistance is a third P-type transistor P₃The equivalent resistance of (c).

If the photodiode 107 is interfered by the ambient light, a DC current I is generated₁Continuously increases in the third P-type transistor P₃The current in the saturation region is less than the direct current I₁While in the fourth P-type transistor P₄Before starting, flows through the third P-type transistor P₃Current of (I)₃Continuously increasing, current mirror Q₁And a current mirror Q₂Making the current flowing through the point-first connection equal to the current flowing through the third P-type transistor P₃Current of (I)₃The voltage of the first connecting point M is V_M=V_DD-I₃R, the first connection point M is connected to the fourth P-type transistor P₄Of the fourth P-type transistor P, thereby₄V of_gs=I₃R; when the direct current I₁When further increased, I₃Also gradually increases, the current flowing through R also gradually increases, the voltage of the first connecting point M gradually decreases when I₁To a certain extent, the voltage of the first connection point M is sufficiently low, and the fourth P-type transistor P₄V of_gsGreater than a threshold voltage V_tWhile the fourth P type transistor P₄Is openedFlows through the fourth P-type transistor P₄Current of (I)₄Providing additional current when I₃+I₄=I₁。

The photoelectric amplification circuit 100 provided by the embodiment of the invention can control the first transistor 102 to be turned on step by step according to the magnitude of the environmental interference, so that the direct current interference is resisted, the noise is minimized, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

With continued reference to fig. 6, optionally, the dc current flowing through the photodiode 107 is no greater than the third P-type transistor P₃Current of the saturation region, first power supply V_DDIs less than the difference between the voltage of the fourth P-type transistor P and the voltage of the first connection point M₄Threshold voltage of, a third P-type transistor P₃Turn on, fourth P-type transistor P₄And (6) turning off.

Illustratively, a direct current I flowing through the photodiode 107₁Not greater than the third P-type transistor P₃At this time, the third P-type transistor P₃Turn on, fourth P-type transistor P₄Off, third P-type transistor P₃Is a direct current I₁Providing a path through the third P-type transistor P₃Current of (I)₃Equal to direct current I₁First resistance R_fNo dc signal passes.

The embodiment of the invention provides a photoelectric amplification circuit 100, a differential amplifier 104 collects direct current signals at two ends of a feedback resistor, a control circuit 105 controls a first transistor 102 to be turned on according to an output signal of the differential amplifier 104, the photoelectric amplification circuit 100 can resist direct current interference and simultaneously ensure minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

With continued reference to FIG. 6, optionally, the DC current flowing through the photodiode 107 is greater than the third P-type transistor P₃Current of the saturation region, first power supply V_DDIs greater than the fourth P-type transistor P₄Threshold voltage of, a third P-type transistor P₃And a fourth P type transistor P₄Are all turned on.

Examples of the inventionCharacteristically, a direct current I flowing through the photodiode 107₁Is larger than the third P-type transistor P₃At this time, the third P-type transistor P₃And a fourth P type transistor P₄Are all turned on, and the third P type transistor P₃And a fourth P type transistor P₄In parallel, as a direct current I₁Providing a path through the third P-type transistor P₃And a fourth P type transistor P₄Is equal to the direct current I₁I.e. I₃+I₄=I₁First resistance R_fNo dc signal passes.

The embodiment of the invention provides a photoelectric amplification circuit 100, a differential amplifier 104 collects direct current signals at two ends of a feedback resistor, a control circuit 105 controls a first transistor 102 to be turned on step by step according to an output signal of the differential amplifier 104, the photoelectric amplification circuit 100 can resist direct current interference and simultaneously ensure minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

With continued reference to fig. 6, optionally, the bandwidth 104 of the differential amplifier is less than the frequency of the alternating current flowing through the photodiode 107.

The embodiment of the invention provides a photoelectric amplification circuit 100, wherein a differential amplifier 104 collects direct current signals at two ends of a feedback resistor, a control circuit 105 controls a first transistor 102 to be turned on step by step according to an output signal of the differential amplifier 104, the bandwidth of the differential amplifier 104 is smaller than the frequency of an alternating current signal, the differential amplifier 104 is ensured to collect only the direct current signal, the photoelectric amplification circuit 100 can resist direct current interference and simultaneously ensure minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

Fig. 7 is a circuit diagram of another photoelectric amplification circuit 100 according to an embodiment of the present invention, referring to fig. 7, optionally, the current control module 103 further includes: a first capacitor C₁A second capacitor C₂A third capacitor C₃And a fourth capacitance C₄First capacitor C₁A second capacitor connected between the second output terminal of the differential amplifier 104 and the ground terminal, and a third capacitor C connected between the first output terminal of the differential amplifier 104 and the ground terminal₃One end of which is connected to the first P-type transistor P₁And a first power supply V_DDBetween, a fourth capacitance C₄Is connected to the first connection point M and the first power supply V_DDFirst capacitor C₁A second capacitor C₂A third capacitor C₃And a fourth capacitance C₄Are used to reduce the output bandwidth of the differential amplifier 104.

The embodiment of the invention provides a photoelectric amplification circuit 100, wherein a differential amplifier 104 collects direct current signals at two ends of a feedback resistor, a control circuit 105 controls a first transistor 102 to be turned on step by step according to an output signal of the differential amplifier 104, the bandwidth of the differential amplifier 104 is reduced by connecting a capacitor, the differential amplifier 104 is ensured to collect only the direct current signals, the photoelectric amplification circuit 100 can resist direct current interference and simultaneously ensure the minimum noise, and the effects of high sensitivity, strong anti-interference capability and high signal-to-noise ratio are achieved.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.