Current detection circuit

Abstract

The present application relates to a current detection circuit, in which a bias module provides a first current, a reference current generation module outputs a reference current, and a load circuit generation module outputs a load current. In a working state, a transconductance module turns on a conductive path between the reference current generation module, the load current generation module, the bias module, and the cathode of a photodiode, thereby obtaining a second current flowing to the bias module and a light sensing current flowing to the photodiode. Since the bias module also biases the current value of the second current to the current value of the first current, the current comparison module finally mirrors the output of the load current and the first current, and generates a comparison result of the load current and the first current, which can characterize the magnitude relationship between the reference current and the light sensing current. Compared with the traditional solution using a TIA amplifier, the detection circuit of this solution has low power consumption and occupies a small area.

Description

Technical Field

[0001] The present application relates to the field of photoelectric detection, and in particular to a current detection circuit. Background Art

[0002] Photoelectric detection devices are used to detect the photocurrent of photodiodes. When the photocurrent reaches a threshold intensity, they output a corresponding digital signal for further processing by a signal processor, resulting in a comparison between the photocurrent and the current intensity threshold. Traditional current detection methods use a TIA amplifier and comparator. This solution offers high accuracy but occupies a large area and consumes high power. However, many applications, such as optical encoders, do not require high photoelectric detection accuracy but instead require a large number of detection channels. Therefore, these applications require a small circuit footprint and low power consumption. Summary of the Invention

[0003] The present application provides a current detection circuit that occupies a small area and has low power consumption.

[0004] A current detection circuit is applied to a photodiode, the current detection circuit comprising:

[0005] A bias module, configured to provide a first current;

[0006] A reference current generating module, used for outputting a reference current;

[0007] A load current generating module, used for outputting load current;

[0008] a transconductance module, wherein a first connection end of the transconductance module is respectively connected to the reference current generating module and the load current generating module, and a second connection end of the transconductance module is respectively connected to the cathode of the photodiode and the bias module, and the transconductance module is used to conduct a conductive path between the reference current generating module, the load current generating module, the bias module, and the cathode of the photodiode in a working state to obtain a second current flowing to the bias module and a light sensing current flowing to the photodiode;

[0009] The bias module is further configured to bias the current value of the second current to the current value of the first current;

[0010] A current comparison module is connected to the load current generation module and the bias module respectively, and is used to mirror-output the load current and the first current, and generate a comparison result of the load current and the first current to characterize the magnitude relationship between the reference current and the light sensing current.

[0011] In one embodiment, the load current generating module includes a switch tube PM1, the bias module includes a switch tube PM2, and the current comparing module includes a switch tube PM3 and a switch tube PM4;

[0012] The first connection terminal of the switch tube PM1 is used to receive the current I E1 The second connection terminal and the control terminal of the switch tube PM1 are connected in common, and are respectively connected to the control terminal of the switch tube PM3 and the first connection terminal of the transconductance module;

[0013] The first connection terminal of the switch tube PM2 is connected to the control terminal, and the first connection terminal of the switch tube PM2 is used to receive the first current; the second connection terminal of the switch tube PM2 is connected to the ground terminal;

[0014] The first connection terminal of the switch tube PM3 is used to receive the current I E2 , the second connection end of the switch tube PM3 is connected to the first connection end of the switch tube PM4;

[0015] The control end of the switch tube PM4 is connected to the control end of the switch tube PM2 , and the second connection end of the switch tube PM4 is connected to the ground end.

[0016] In one embodiment, the bias module further includes:

[0017] The switch tube PM5 has a control end connected to the control end of the switch tube PM2, a first connection end connected to the second connection end of the transconductance module, and a second connection end connected to the ground end.

[0018] In one embodiment, the reference current generating module includes a switch transistor PM6 and a switch transistor PM7;

[0019] The control terminal and the first connection terminal of the switch tube PM6 are connected together, and are connected to the control terminal of the switch tube PM7 and the bias module. The second connection terminal of the switch tube PM6 is used to receive the current I E3 ;

[0020] The first connection terminal of the switch tube PM7 is used to receive the current I E4 , the second connection end of the switch tube PM7 is connected to the first connection end of the transconductance module;

[0021] The bias module is further configured to bias the current flowing through the switch tube PM6 to a target current, so that the switch tube PM7 mirrors the target current to obtain the reference current.

[0022] In one embodiment, the bias module further includes a plurality of bias units, each of which is connected to the first connection end of the switch tube PM6, and each of which is used to receive and bias the current of its own branch to a target sub-current according to an external control signal to obtain the target current.

[0023] In one embodiment, the bias unit includes a switch transistor PM8 and a switch transistor PM9;

[0024] The first connection end of the switch transistor PM8 is connected to the first connection end of the switch transistor PM6, the control end of the switch transistor PM8 is used to receive the external control signal, and the second connection end of the switch transistor PM8 is connected to the first connection end of the switch transistor PM9;

[0025] The control end of the switch tube PM9 is connected to the control end of the switch tube PM2 , and the second connection end of the switch tube PM9 is connected to the ground end.

[0026] In one embodiment, the bias module further includes:

[0027] The bias output unit is connected to the first connection terminal and the control terminal of the switch tube PM2 respectively, and is used to output the first current.

[0028] In one embodiment, the bias output unit is further configured to output a bias voltage;

[0029] The control end of the transconductance module is also connected to the bias output unit, and is used to receive the bias voltage and enter the working state according to the bias voltage.

[0030] In one embodiment, the current comparison module further includes:

[0031] A Schmitt comparator, wherein the input end of the Schmitt comparator is respectively connected to the second connection end of the switch tube PM3 and the first connection end of the switch tube PM4.

[0032] In one embodiment, the current comparison module further includes:

[0033] A three-cascade inverter, wherein the input end of the three-cascade inverter is connected to the output end of the Schmidt comparator.

[0034] The above-mentioned current detection circuit provides a first current through the bias module, the reference current generation module outputs the reference current, and the load circuit generation module outputs the load current. In the working state, the transconductance module turns on the conductive path between the reference current generation module, the load current generation module, the bias module, and the cathode of the photodiode, thereby obtaining a second current flowing to the bias module and a light sensing current flowing to the photodiode. Since the bias module also biases the current value of the second current to the current value of the first current, the final current comparison module mirrors the output of the load current and the first current, and generates a comparison result of the load current and the first current, which can characterize the magnitude relationship between the reference current and the light sensing current. Compared with the traditional solution using the TIA amplifier, the detection circuit of this solution has low power consumption and occupies a small area. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a structural block diagram of a current detection circuit according to an embodiment of the present application;

[0036] Figure 2 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0037] Figure 3 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0038] Figure 4 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0039] Figure 5 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0040] Figure 6 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0041] Figure 7 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0042] Figure 8 This is a circuit structure diagram of a bias output unit according to an embodiment of the present application;

[0043] Figure 9 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0044] Figure 10 This is a structural block diagram of a current detection circuit according to another embodiment of the present application;

[0045] Figure 11 This is a structural block diagram of a current detection circuit according to another embodiment of the present application. DETAILED DESCRIPTION

[0046] It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0047] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. The connection can be a direct connection or an indirect connection.

[0049] In addition, the descriptions of "first", "second", etc. in this application are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0050] Figure 1 FIG. 1 is a block diagram of a current detection circuit according to an embodiment of the present invention. The current detection circuit is applied to a photodiode D1. Figure 1As shown, the current detection circuit includes a bias module 110, a reference current generating module 120, a load current generating module 130, a transconductance module 140 and a current comparison module 150; the bias module 110 is used to provide a first current; the reference current generating module 120 is used to output a reference current; the load current generating module 130 is used to output a load current; the first connection end of the transconductance module 140 is respectively connected to the reference current generating module 120 and the load current generating module 130, and the second connection end of the transconductance module 140 is respectively connected to the cathode of the photodiode D1 and the bias module 110, and the transconductance module 140 is used to compare the current when working. In the state, a conductive path is turned on between the reference current generating module 120, the load current generating module 130, the bias module 110, and the cathode of the photodiode D1 to obtain a second current flowing to the bias module 110 and a light sensing current flowing to the photodiode D1; the bias module 110 is also used to bias the current value of the second current to the current value of the first current; the current comparison module 150 is connected to the load current generating module 130 and the bias module 110 respectively, and is used to mirror the output load current and the first current, and generate a comparison result of the load current and the first current to characterize the magnitude relationship between the reference current and the light sensing current.

[0051] In one embodiment, the working state of the transconductance module 140 can be controlled by the bias module 110 through power supply. Specifically, since the reference current generating module 120 and the load current generating module 130 are connected to the first connection terminal of the transconductance module 140, and the cathode of the photodiode D1 and the bias module 110 are connected to the second connection terminal of the transconductance module 140, when the transconductance module 140 is turned on, the reference current I c and load current I r The current flows to the bias module 110 and the photodiode D1 through the transconductance module 140, wherein the current flowing to the bias module 110 is the second current I2, and the current flowing to the photodiode D1 is the light sensing current I o ; Among them, the light sensing current is used to represent the intensity of the light signal sensed by the photodiode D1; thus, based on the current conservation law, the following relationship (1) can be obtained:

[0052] I c +I r = I²+I o

[0053] When the bias module 110 is connected to the reference current generating module 120 and the load current generating module 130 through the transconductance module 140, the bias module 110 can bias the current value of the second current I2 outputted by the reference current generating module 120 and the load current generating module 130 to the current value of the first current I1, that is, I2 = I1. The bias module 110 can provide the first current I1, which can bias the second current based on the first current. In this way, the above relationship (1) can be converted into the following relationship (2):

[0054] I c +I r = I1+I o

[0055] According to the relationship (2), the load current expression I can be obtained r = I1+I o -I c The current comparison module 150 is connected to the load current generating module 130 and the bias module 110, respectively, and can mirror the load current I provided by the load current generating module 130. r and the first current I1 provided by the bias module 110, thereby generating a comparison result between the load current and the first current, which can be expressed as I r -I1, combined with the above load current expression, the comparison result I r -I1=I o -I c That is, the comparison result between the load current and the first current can represent the magnitude relationship between the reference current and the light sensing current, thereby determining whether the light sensing current is greater than, equal to, or less than the reference current. The reference current can be set manually, for example, to the target current of photodiode D1 corresponding to the target light intensity. The comparison result between the load current and the first current can be used to determine the magnitude relationship between the target current and the light sensing current, and thus the magnitude relationship between the light intensity sensed by photodiode D1 and the target light intensity. This detection circuit does not use a TIA amplifier, has low power consumption, a simple structure, and occupies a small area.

[0056] The above-mentioned current detection circuit provides a first current through the bias module 110, the reference current generation module 120 outputs the reference current, and the load circuit generation module outputs the load current. In the working state, the transconductance module 140 turns on the conductive path between the reference current generation module 120, the load current generation module 130, the bias module 110, and the cathode of the photodiode D1, thereby obtaining a second current flowing to the bias module 110 and a light sensing current flowing to the photodiode D1. Since the bias module 110 also biases the current value of the second current to the current value of the first current, the current comparison module 150 finally mirrors the output of the load current and the first current, and generates a comparison result of the load current and the first current, which can represent the magnitude relationship between the reference current and the light sensing current. Compared with the traditional solution using the TIA amplifier, the detection circuit of this solution has low power consumption and occupies a small area, and is more suitable for multi-channel photoelectric current detection scenarios.

[0057] In one embodiment, Figure 2 As shown, the load current generating module 130 includes a switch tube PM1, the bias module 110 includes a switch tube PM2, and the current comparing module 150 includes a switch tube PM3 and a switch tube PM4; the first connection terminal of the switch tube PM1 is used to receive the current I E1 The second connection terminal of the switch tube PM1 is connected to the control terminal in common, and is respectively connected to the control terminal of the switch tube PM3 and the first connection terminal of the transconductance module 140; the first connection terminal of the switch tube PM2 is connected to the control terminal in common, and the first connection terminal of the switch tube PM2 is used to receive the first current; the second connection terminal of the switch tube PM2 is connected to the ground terminal; the first connection terminal of the switch tube PM3 is used to receive the current I E2 The second connection end of the switch tube PM3 is connected to the first connection end of the switch tube PM4; the control end of the switch tube PM4 is connected to the control end of the switch tube PM2, and the second connection end of the switch tube PM4 is connected to the ground end.

[0058] Specifically, on one hand, the switch tube PM1 and the switch tube PM3 can be P-type MOS tubes. Since the switch tube PM3 and the switch tube PM1 form a pair of current mirrors, the load current I output by the switch tube PM1 can be replicated. r On the other hand, the switch transistors PM2 and PM4 can be N-type MOS transistors. After receiving the first current I1, the switch transistor PM2 is turned on. Since the switch transistors PM4 and PM2 form a pair of current mirrors, the first current I1 received by the switch transistor PM2 can be replicated. The second connection terminal of the switch transistor PM3 is connected to the first connection terminal of the switch transistor PM4 to output the load current I r and the comparison result of the first current I1, wherein the comparison result may be the voltage at the common connection point between the switch tube PM3 and the switch tube PM4.

[0059] It can be understood that, in fact, the current in the conductive path between the second connection terminal of the switch tube PM3 and the first connection terminal of the switch tube PM4 should be a unique value; when the load current I r When the current is equal to the first current I1, the switch tube PM3 can successfully copy the load current I r The current value of the first current I1 can be successfully copied by the switch tube PM4. At this time, the voltage at the common connection point of the switch tube PM3 and the switch tube PM4 is equal to the critical voltage. When the load current I r When the current is greater than the first current I1, the current value copied by the switch tube PM3 cannot actually reach the load current I r , and can only reach the first current I1, at this time the switch tube PM3 desaturates, and the voltage at the common connection point of the switch tube PM3 and the switch tube PM4 is greater than the critical voltage; when the first current I1 is greater than the load current I r When the current value copied by the switch tube PM4 does not actually reach the first current I1, but can only reach the load current I r At this point, the switch PM4 is desaturated, and the voltage at the common connection point between the switches PM3 and PM4 is less than the critical voltage. Therefore, based on the circuit structure of this embodiment, the comparison result between the load current and the first current, i.e., the magnitude relationship between the reference current and the light sensing current, can be determined by obtaining the voltage at the common connection point between the switches PM3 and PM4.

[0060] In one embodiment, Figure 3 As shown, the bias module 110 further includes a switch tube PM5, a control end of the switch tube PM5 is connected to the control end of the switch tube PM2, a first connection end of the switch tube PM5 is connected to the second connection end of the transconductance module 140, and a second connection end of the switch tube PM5 is connected to the ground end.

[0061] It can be understood that the switch transistor PM5 can be an N-type MOS transistor. Since the switch transistor PM5 and the switch transistor PM2 form a pair of current mirrors, the first current I1 flowing into the switch transistor PM2 can be replicated, so that the current value of the second current I1 in the conductive path is equal to the current value of the first current I1.

[0062] In one embodiment, Figure 4 As shown, the reference current generating module 120 includes a switch tube PM6 and a switch tube PM7; the control terminal and the first connection terminal of the switch tube PM6 are connected in common, and are connected to the control terminal of the switch tube PM7 and the bias module 110, and the second connection terminal of the switch tube PM6 is used to receive the current I E3 The first connection terminal of the switch tube PM7 is used to receive the current I E4, the second connection end of the switch tube PM7 is connected to the first connection end of the transconductance module 140; the bias module 110 is also used to bias the current flowing through the switch tube PM6 to a target current, so that the switch tube PM7 can obtain a reference current after mirroring the target current.

[0063] It is understood that both the switch transistor PM6 and the switch transistor PM7 can be P-type MOS transistors. After the conductive path of the switch transistor PM6 is turned on, the bias module 110 can bias the current flowing through the switch transistor PM6 to a target current. Because the switch transistor PM7 forms a current mirror with the switch transistor PM6, the switch transistor PM7 can replicate the target current to obtain a reference current. The target current is the current of the photodiode D1 corresponding to the target light intensity.

[0064] In one embodiment, Figure 5 As shown, the bias module 110 further includes a plurality of bias units 111, each bias unit 111 being connected to the first connection end of the switch tube PM6, and each bias unit 111 being used to receive and bias the current of its own branch to a target sub-current according to an external control signal to obtain a target current.

[0065] It can be understood that the bias unit 111 has a current biasing function. When the switch tube PM6 is turned on and current flows through, each bias unit 111 can bias the current on its own branch to obtain a target sub-current. Among them, the external control signal can be used to control whether each bias unit 111 generates the target sub-current. When the target current size is known, the bias unit 111 that needs to work can be determined, and then an external control signal of a specific value is sent to each bias unit 111 to drive the corresponding bias unit 111 to bias the current of its own branch to the target sub-current, so that the current flowing through the switch tube PM6 reaches the target current.

[0066] By controlling the bias unit 111 through an external control signal, the target current can be adjusted, ultimately achieving the desired target current. The target sub-currents obtained by biasing each bias unit 111 can be the same or different. When the target sub-currents are the same, the desired target current can be obtained by controlling the number of bias units 111 operating. When the target sub-currents are different, the bias units 111 can be combined and the bias units 111 in the combination can be controlled to operate, ultimately achieving the desired target current.

[0067] In one embodiment, the bias unit 111 includes a switch transistor PM8 and a switch transistor PM9; a first connection terminal of the switch transistor PM8 is connected to the first connection terminal of the switch transistor PM6, a control terminal of the switch transistor PM8 is used to receive an external control signal, and a second connection terminal of the switch transistor PM8 is connected to the first connection terminal of the switch transistor PM9; a control terminal of the switch transistor PM9 is connected to the control terminal of the switch transistor PM2, and a second connection terminal of the switch transistor PM9 is connected to the ground terminal.

[0068] For example, the number of bias units 111 is 4 and the external control signal is represented by the symbol “s”. Figure 6 As shown, each bias unit 111 includes a switch transistor PM8 and a switch transistor PM9, wherein the switch transistor PM8 and the switch transistor PM9 can be N-type MOS transistors, and the specifications and models of the switch transistors PM9 can be the same or different to obtain the same or different target sub-currents. In one embodiment, the reference current is set to I b , the target sub-currents obtained by biasing the four switch tubes PM9 are I b , 2I b 、4I b 、8I b By combining the switch tubes PM9, we can get I b ~15I b A total of 15 target currents.

[0069] In one embodiment, Figure 7 As shown, the bias module 110 further includes: a bias output unit 112, which is respectively connected to the first connection terminal and the control terminal of the switch tube PM2, and is used to output a first current.

[0070] In one embodiment, the bias output unit 112 is further configured to output a bias voltage U0; the control terminal of the transconductance module 140 is further connected to the bias output unit 112 for receiving the bias voltage and entering a working state according to the bias voltage. Figure 7 shown.

[0071] The bias output unit 112 can output a first current of a constant value; in one embodiment, Figure 8As shown, the bias output unit 112 may include: a switch tube M1, a switch tube M2, a plurality of switch tubes M3, a switch tube M4, a switch tube M5, a switch tube M6, a switch tube M7, a switch tube M8, a switch tube M9, a switch tube M10, a switch tube M11, a switch tube M12, a switch tube M13, a switch tube M14, a switch tube M15, a switch tube M16, a switch tube M17, a switch tube M18, a switch tube M19, a switch tube M20, a switch tube M21, a switch tube M22, a switch tube M23, a switch tube M24, a switch tube M25, a switch tube M26, a switch tube M27, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5 and a capacitor C1.

[0072] Wherein, each switch tube can be a MOS tube, and the control terminals of the switch tube M1, the switch tube M2, multiple switch tubes M3, and the switch tube M4 are connected in common to receive an external drive signal; the drain of the switch tube M1 and the drain of the switch tube M2 are connected in common, and the switch tubes M3 are connected in cascade; the first-stage switch tubes M3, the switch tube M7, the switch tube M9, the switch tube M10, the switch tube M14, the switch tube M16, the switch tube M18, and the switch tube M20 are connected in common to the source, and are connected to the first terminal of the capacitor C1 to receive the current I DThe drain of the final stage switch tube M3, the drain of the switch tube M4, the drain of the switch tube M5, the gate of the switch tube M6 and the second end of the capacitor C1 are connected; the drain of the switch tube M6, the drain and gate of the switch tube M8, the gate of the switch tube M7, the drain of the switch tube M9, the gate of the switch tube M10, the gate of the switch tube M11, the gate of the switch tube M14, the gate of the switch tube M16, the gate of the switch tube M17, the gate of the switch tube M18, the gate of the switch tube M19, and the gate of the switch tube M20 The gate of the switch tube M21, the gate of the switch tube M22, the gate of the switch tube M23 and the drain of the switch tube M12 are connected in common; the drain of the switch tube M15 is connected to the first connection end of the switch tube PM2, and the gate of the switch tube M15 is used to receive a driving signal to obtain a first current after being turned on; the drain of the switch tube M7 is connected to the source of the switch tube M8; the drain of the switch tube M10 is connected to the source of the switch tube M11; the drain of the switch tube M16 is connected to the source of the switch tube M17; the drain of the switch tube M18 is connected to the source of the switch tube M19; The drain of the switch tube M17 is connected to the source of the switch tube M19; the switch tubes M20, M21, M22, and M23 are connected in sequence; the gate of the switch tube M5, the drain of the switch tube M14, the gate of the switch tube M12, the gate and drain of the switch tube M13 are connected together, and connected to the drain of the switch tube M11; the drain of the switch tube M17, the gate and drain of the switch tube M24, the gate of the switch tube M26, and the drain of the switch tube M27 are connected together, and connected to the transconductance module 140 to provide Bias voltage U0; the source of the switch tube M24, the gate and drain of the switch tube M25 are connected together; the resistors R1, R2, R3, and R4 are connected in sequence; the source of the switch tube M2, the source of the switch tube M4, the source of the switch tube M5, the source of the switch tube M6, the gate and source of the switch tube M14, the resistors R4, R5, the source of the switch tube M13, the source of the switch tube M25, the source and drain of the switch tube M26, and the source of the switch tube M27 are connected together and connected to the ground.

[0073] In one embodiment, Figure 9 As shown, the current comparison module 150 further includes a Schmitt comparator, and the input terminals of the Schmitt comparator are respectively connected to the second connection terminal of the switch tube PM3 and the first connection terminal of the switch tube PM4.

[0074] It can be understood that since the front-stage circuit has low power consumption and small current, there may be current jitter. By using a Schmidt comparator, the output signal can be shaped and compared with the threshold voltage to obtain a stable digital signal, which makes it easier to intuitively obtain the comparison result of the load current and the first current.

[0075] The Schmitt comparator may include a switch N1, a switch N2, a switch N3, a switch N4, a switch N5, a switch N6, and a switch N7. The switch N1, the switch N2, the switch N3, and the switch N4 are connected to a common gate, and are respectively connected to the second connection terminal of the switch PM3, the first connection terminal of the switch PM4, and the drain of the switch N7; the switch N1, the switch N2, the switch N3, and the switch N4 are connected in cascade in sequence, and the source of the switch N1 is used to receive the current I E5 The source of the switch tube N4 is connected to the ground terminal; the drain of the switch tube N5 is connected to the drain of the switch tube N1 and the source of the switch tube N2 respectively; the drain of the switch tube N6 is connected to the drain of the switch tube N4 and the source of the switch tube N3 respectively; the source of the switch tube N5 and the source of the switch tube N6 are respectively used to receive the voltage VSS; the gate of the switch tube N5, the gate of the switch tube N6, the drain of the switch tube N2, and the drain of the switch tube N3 are connected in common to serve as the output end of the Schmitt comparator.

[0076] In one embodiment, the current comparison module 150 further includes three cascade inverters, such as Figure 10 As shown, the input terminals of the three-cascade inverters are connected to the output terminals of the Schmitt comparator.

[0077] Specifically, the three-stage cascade inverter may include a switch tube N8, a switch tube N9, a switch tube N10, a switch tube N11, a switch tube N12, and a switch tube N13. The sources of the switch tubes N8, N10, and N12 are respectively used to receive the current I E6 , I E7 , I E8 The switch tubes N9, N11, and N13 have a common source connected and are connected to the ground; the switch tubes N8 and N9 have a common gate connected and are connected to the output of the Schmidt comparator; the switch tubes N8 and N9 have a common drain connected and are connected to the gates of the switch tubes N10 and N11; the switch tubes N10 and N11 have a common drain connected and are connected to the gates of the switch tubes N12 and N13; the switch tubes N12 and N13 have a common drain connected to serve as the output of the current comparison module 150.

[0078] In one embodiment, the transconductance module 140 may include a switch tube PM10, a control terminal of the switch tube PM10 is connected to the bias module 110, a first connection terminal of the switch tube PM10 is connected to the second connection terminal of the switch tube PM1, and a second connection terminal of the switch tube PM10 is connected to the first connection terminal of the switch tube PM5.

[0079] The embodiment of the present invention further provides a current detection circuit, such as Figure 11As shown, the current detection circuit includes a bias module 110, a reference current generating module 120, a load current generating module 130, a transconductance module 140 and a current comparison module 150.

[0080] The bias module 110 includes a switch tube PM2, a plurality of switch tubes PM8 and PM9, a switch tube PM5 and a bias output unit 112. Figure 8 As shown, the bias output unit 112 includes a switch tube M1, a switch tube M2, a plurality of switch tubes M3, a switch tube M4, a switch tube M5, a switch tube M6, a switch tube M7, a switch tube M8, a switch tube M9, a switch tube M10, a switch tube M11, a switch tube M12, a switch tube M13, a switch tube M14, a switch tube M15, a switch tube M16, a switch tube M17, a switch tube M18, a switch tube M19, a switch tube M20, a switch tube M21, a switch tube M22, a switch tube M23, switches M24, M25, M26, M27, resistors R1, R2, R3, R4, R5, and capacitor C1; reference current generation module 120 includes switches PM6 and PM7; load current generation module 130 includes switch PM1; transconductance module 140 includes switch M13; current comparison module 150 includes switches PM3 and PM4, a Schmitt comparator, and a three-stage cascade inverter. The Schmitt comparator may include switches N1, N2, N3, N4, N5, N6, and N7; and the three-stage cascade inverter may include switches N8, N9, N10, N11, N12, and N13.

[0081] The specific connection relationship of each component in the current detection circuit of this embodiment can be referred to Figure 11 As for the above-mentioned current detection circuit embodiment, its working principle and specific implementation effects can also be referred to the above-mentioned embodiment, which will not be described in detail here.

[0082] The above description is only a preferred embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A current detection circuit, characterized in that: Applied to a photodiode, the current detection circuit includes: A bias module, configured to provide a first current; A reference current generating module, used for outputting a reference current; A load current generating module, used for outputting load current; a transconductance module, wherein a first connection end of the transconductance module is respectively connected to the reference current generating module and the load current generating module, and a second connection end of the transconductance module is respectively connected to the cathode of the photodiode and the bias module, and the transconductance module is configured to, in an operating state, conduct a conductive path between the reference current generating module, the load current generating module, the bias module, and the cathode of the photodiode to obtain a second current flowing to the bias module and a light sensing current flowing to the photodiode; wherein the sum of the current values of the reference current and the load current is equal to the sum of the current values of the second current and the light sensing current; The bias module is further configured to bias the current value of the second current to the current value of the first current; A current comparison module is connected to the load current generation module and the bias module respectively, and is used to mirror-output the load current and the first current, and generate a comparison result of the load current and the first current to characterize the magnitude relationship between the reference current and the light sensing current.

2. The current detection circuit according to claim 1, wherein: The load current generating module includes a switch tube PM1, the bias module includes a switch tube PM2, and the current comparing module includes a switch tube PM3 and a switch tube PM4; The first connection terminal of the switch tube PM1 is used to receive the current I E1 The second connection terminal and the control terminal of the switch tube PM1 are connected in common, and are respectively connected to the control terminal of the switch tube PM3 and the first connection terminal of the transconductance module; The first connection terminal of the switch tube PM2 is connected to the control terminal, and the first connection terminal of the switch tube PM2 is used to receive the first current; the second connection terminal of the switch tube PM2 is connected to the ground terminal; The first connection terminal of the switch tube PM3 is used to receive the current I E2 , the second connection end of the switch tube PM3 is connected to the first connection end of the switch tube PM4; The control end of the switch tube PM4 is connected to the control end of the switch tube PM2 , and the second connection end of the switch tube PM4 is connected to the ground end.

3. The current detection circuit according to claim 2, characterized in that: The bias module further includes: The switch tube PM5 has a control end connected to the control end of the switch tube PM2, a first connection end connected to the second connection end of the transconductance module, and a second connection end connected to the ground end.

4. The current detection circuit according to claim 2, wherein: The reference current generating module includes a switch tube PM6 and a switch tube PM7; The control terminal and the first connection terminal of the switch tube PM6 are connected together, and are connected to the control terminal of the switch tube PM7 and the bias module. The second connection terminal of the switch tube PM6 is used to receive the current I E3 ; The first connection terminal of the switch tube PM7 is used to receive the current I E4 , the second connection end of the switch tube PM7 is connected to the first connection end of the transconductance module; The bias module is further configured to bias the current flowing through the switch tube PM6 to a target current, so that the switch tube PM7 mirrors the target current to obtain the reference current.

5. The current detection circuit according to claim 4, characterized in that: The bias module further includes a plurality of bias units, each of which is connected to the first connection end of the switch tube PM6. Each of the bias units is used to receive and bias the current of its own branch to a target sub-current according to an external control signal to obtain the target current.

6. The current detection circuit according to claim 5, characterized in that: The bias unit includes a switch tube PM8 and a switch tube PM9; The first connection end of the switch transistor PM8 is connected to the first connection end of the switch transistor PM6, the control end of the switch transistor PM8 is used to receive the external control signal, and the second connection end of the switch transistor PM8 is connected to the first connection end of the switch transistor PM9; The control end of the switch tube PM9 is connected to the control end of the switch tube PM2 , and the second connection end of the switch tube PM9 is connected to the ground end.

7. The current detection circuit according to claim 2, characterized in that: The bias module further includes: The bias output unit is connected to the first connection terminal and the control terminal of the switch tube PM2 respectively, and is used to output the first current.

8. The current detection circuit according to claim 7, characterized in that: The bias output unit is further used to output a bias voltage; The control end of the transconductance module is also connected to the bias output unit, and is used to receive the bias voltage and enter the working state according to the bias voltage.

9. The current detection circuit according to claim 2, characterized in that: The current comparison module also includes: A Schmitt comparator, wherein the input end of the Schmitt comparator is respectively connected to the second connection end of the switch tube PM3 and the first connection end of the switch tube PM4.

10. The current detection circuit according to claim 9, characterized in that: The current comparison module also includes: A three-cascade inverter, wherein the input end of the three-cascade inverter is connected to the output end of the Schmidt comparator.

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