Sensing circuit and operating method thereof

Abstract

The invention provides a sensing circuit and an operation method thereof. The sensing circuit comprises a light sensing element, a reset circuit, a light sensing circuit, a reading circuit and a feedback circuit, the light sensing element is coupled to the reset circuit, the light sensing circuit and the feedback circuit on a first node. The light sensing circuit generates a light sensing result based on a first reference voltage according to a first voltage on a first node. The reading circuit outputs a light sensing result according to the first control signal; during exposure, the feedback circuit forms a transmission path between the first node and a second reference voltage, and conducts the transmission path according to a second control signal to discharge the first node so as to adjust the first voltage, thereby improving the voltage difference of the light sensing result under different illumination intensities.

Description

Technical Field

[0001] The present invention relates to an electronic circuit, and more particularly to a sensing circuit using light sensing and an operating method thereof. Background Art

[0002] Optical fingerprint recognition can realize fingerprint recognition function on the display through light sensing elements. Generally speaking, the stronger the light intensity, the greater the voltage difference generated by the light sensing element, which makes the image contrast higher. However, under different light intensities, the difference between the various voltage differences generated by the sensing circuit using light sensing elements is very small, resulting in low image contrast. Summary of the invention

[0003] The embodiment of the present invention provides a sensing circuit, which can improve the voltage difference of light sensing results under different light intensities, thereby improving the contrast of images.

[0004] The sensing circuit of an embodiment of the present invention includes a light sensing element, a reset circuit, a light sensing circuit, a read circuit and a feedback circuit; the reset circuit is coupled to the light sensing element; the light sensing circuit is coupled to the light sensing element and the reset circuit at a first node; the light sensing circuit is used to generate a light sensing result based on a first reference voltage according to a first voltage on the first node; the read circuit is coupled to the light sensing circuit; the read circuit is used to output the light sensing result according to a first control signal; the feedback circuit is coupled to the first node; the feedback circuit is used to form a transmission path between the first node and the second reference voltage during exposure, and to discharge the first node according to the second control signal to adjust the first voltage by turning on the transmission path.

[0005] In an embodiment of the sensing circuit of the present invention, during the exposure period, two terminals of the light sensing element, a first terminal and a second terminal of a first transistor in the feedback circuit, and two terminals of a first capacitor in the feedback circuit are coupled to the transmission path.

[0006] In one embodiment of the sensing circuit of the present invention, the control end of the first transistor is coupled to the anode end of the light sensing element at the first node through a second capacitor, the first end of the first transistor and the first end of the first capacitor are coupled to the cathode end of the light sensing element at a second node, and the second end of the first transistor and the second end of the first capacitor receive the second reference voltage.

[0007] In one embodiment of the sensing circuit of the present invention, the feedback circuit comprises:

[0008] A first transistor having a first terminal coupled to one terminal of the light sensing element at a second node, and a second terminal of the first transistor receiving the second reference voltage;

[0009] a first capacitor having a first terminal coupled to the second node, and a second terminal of the second capacitor receiving the second reference voltage;

[0010] A second transistor having a control terminal for receiving the second control signal, a first terminal of the second transistor for receiving a third reference voltage, and a second terminal of the second transistor coupled to the control terminal of the first transistor at a third node;

[0011] a second capacitor having a first end coupled to the first node and a second end coupled to the third node;

[0012] A third transistor has a control terminal for receiving the second control signal, a first terminal of the third transistor is coupled to the second node, and a second terminal of the third transistor receives a fourth reference voltage.

[0013] In an embodiment of the sensing circuit of the present invention, a voltage value of the second reference voltage is lower than a voltage value of the fourth reference voltage.

[0014] In one embodiment of the sensing circuit of the present invention, the feedback circuit further includes:

[0015] A third capacitor has a first terminal coupled to the first node, and a second terminal coupled to the second node.

[0016] In one embodiment of the sensing circuit of the present invention, the reset circuit comprises:

[0017] A fourth transistor has a control terminal for receiving the second control signal, a first terminal of the fourth transistor for receiving the first reference voltage, and a second terminal of the fourth transistor coupled to the first node.

[0018] In one embodiment of the sensing circuit of the present invention, the light sensing circuit comprises:

[0019] A fifth transistor has a control terminal coupled to the first node, a first terminal of the fifth transistor receives the first reference voltage, and a second terminal of the fifth transistor is coupled to the read circuit.

[0020] In one embodiment of the sensing circuit of the present invention, the reading circuit comprises:

[0021] A sixth transistor has a control terminal for receiving the first control signal, and a first terminal of the sixth transistor is coupled to the second terminal of the fifth transistor.

[0022] In one embodiment of the sensing circuit of the present invention, during a reset period, the sixth transistor is turned off according to the first control signal, the second transistor, the third transistor and the fourth transistor are turned on according to the second control signal, and the first transistor and the fifth transistor are turned on.

[0023] In one embodiment of the sensing circuit of the present invention, during the exposure period, the sixth transistor is turned off according to the first control signal, the first transistor is turned on according to the voltage on the third node, the second transistor, the third transistor and the fourth transistor are turned off according to the second control signal, and the fifth transistor is turned on according to the first voltage.

[0024] In one embodiment of the sensing circuit of the present invention, during a reading period, the sixth transistor is turned on according to the first control signal, the second transistor, the third transistor and the fourth transistor are turned off according to the second control signal, and the first transistor and the fifth transistor are turned on.

[0025] The present invention also provides an operating method of a sensing circuit, the operating method comprising the following steps: generating a light sensing result based on a first reference voltage by a light sensing circuit according to a first voltage on a first node. The light sensing circuit is coupled to a light sensing element and a reset circuit at the first node; outputting the light sensing result according to a first control signal by a reading circuit; the reading circuit is coupled to the light sensing circuit; forming a transmission path between the first node and a second reference voltage during exposure by a feedback circuit coupled to the first node, and conducting the transmission path according to a second control signal to discharge the first node to adjust the first voltage.

[0026] Based on the above, the sensing circuit and the operating method of the embodiment of the present invention can discharge one end (i.e., the first node) of the light sensing element based on the transmission path formed by the feedback circuit during the exposure period. Therefore, the light sensing element and the light sensing circuit operate according to the adjusted first voltage on this node. In this way, without increasing the length of the exposure period, the sensing circuit can increase the voltage difference of the light sensing result in applications with various light intensities, thereby improving the contrast of the image.

[0027] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a circuit block diagram of a sensing circuit according to an embodiment of the present invention.

[0029] Figure 2 is a flow chart of an operating method of a sensing circuit according to an embodiment of the present invention.

[0030] Figure 3 is a circuit diagram of a sensing circuit according to another embodiment of the present invention.

[0031] Figure 4 According to the present invention Figure 3 Schematic diagram of the operation of the sensing circuit of the embodiment.

[0032] FIG. 5A to FIG. 5C According to the present invention Figure 4 A schematic diagram of the operation of the sensing circuit shown in the embodiment.

[0033] Figure 6 is a circuit diagram of a sensing circuit according to another embodiment of the present invention.

[0034] Wherein, the reference numerals are:

[0035] 100, 300, 600: Sensing circuit

[0036] 110, 310, 610: light sensing element

[0037] 120, 320, 620: Reset circuit

[0038] 130, 330, 630: Light sensing circuit

[0039] 140, 340, 640: Reading circuit

[0040] 150, 350, 650: Feedback circuit

[0041] C1~C2、C3: Capacitors

[0042] DS: Light sensing results

[0043] FV1: First reference voltage

[0044] FV2: Second reference voltage

[0045] FVDD: Reference voltage (first reference voltage)

[0046] FVSS1: Reference voltage (fourth reference voltage)

[0047] FVSS2: Reference voltage (second reference voltage)

[0048] N1: First Node

[0049] N2: Second node

[0050] N3: The third node

[0051] PEP: Exposure Period

[0052] PRD: Read period

[0053] PRST: Reset period

[0054] S210~S230: Steps

[0055] SC1, SCAN1: first control signal

[0056] SC2, SCAN2: second control signal

[0057] t1~t4: time

[0058] T1~T6: Transistor

[0059] V1, V2: voltage value

[0060] VOUT: output terminal

[0061] VREF: Reference voltage (third reference voltage) DETAILED DESCRIPTION

[0062] Some embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The component symbols cited in the following description will be regarded as the same or similar components when the same component symbols appear in different drawings. These embodiments are only part of the present invention and do not disclose all possible implementation methods of the present invention. More specifically, these embodiments are only examples within the scope of the patent application of the present invention.

[0063] Figure 1 is a circuit block diagram of a sensing circuit according to an embodiment of the present invention. Figure 1 The sensing circuit 100 is applicable to a sensing device. The sensing device is, for example, an electronic device that applies optical fingerprint recognition. The sensing device is used to perform a fingerprint recognition operation to realize a fingerprint recognition function, and to display a fingerprint image.

[0064] In the present embodiment, the sensing circuit 100 includes a light sensing element 110, a reset circuit 120, a light sensing circuit 130, a readout circuit 140, and a feedback circuit 150. The light sensing element 110 is coupled to the reset circuit 120, the light sensing circuit 130, and the feedback circuit 150 at a first node N1. The light sensing circuit 130 is coupled to the readout circuit 140. The readout circuit 140 is coupled to a control circuit (not shown) in the sensing device at an output terminal VOUT.

[0065] In this embodiment, the light sensing circuit 130 receives a first reference voltage FV1. The light sensing circuit 130 is controlled to operate by a first voltage on a first node N1. The reading circuit 140 receives a first control signal SC1 and is controlled to operate by the first control signal SC1. The feedback circuit 150 receives a second reference voltage FV2 and a second control signal SC2. The feedback circuit 150 is controlled to operate by the second control signal SC2.

[0066] Figure 2 is a flow chart of an operating method of a sensing circuit according to an embodiment of the present invention. Figure 1 as well as Figure 2 , the sensing circuit 100 executes steps S210 to S230 to perform a light sensing operation. The order of these steps S210 to S220 is only an example and is not limited thereto.

[0067] In step S210 , the light sensing circuit 130 generates a light sensing result DS based on the first reference voltage FV1 according to the first voltage on the first node N1 . The light sensing result DS indicates a signal sensed by the light sensing element 110 .

[0068] In step S220 , the reading circuit 140 outputs the light sensing result DS according to the first control signal SC1 . That is, the reading circuit 140 outputs the light sensing result DS to the control circuit through the output terminal VOUT, so that the control circuit performs the fingerprint recognition operation according to the light sensing result DS.

[0069] In step S230, during the exposure period, the feedback circuit 150 forms a transmission path between the first node N1 and the second reference voltage FV2, and turns on the transmission path according to the second control signal SC2 to discharge the first node N1 to adjust the first voltage. Figure 4 The exposure period PEP is shown. The length of the exposure period can be adjusted based on design requirements and fingerprint recognition functions.

[0070] That is, during the sensing period of the light sensing element 110 , the charges on the first node N1 are discharged through the transmission path, so that the first voltage on the first node N1 is pulled down.

[0071] It is worth mentioning that, through the transmission path formed by the feedback circuit 150 during the exposure period, the sensing circuit 100 can discharge the first node N1. In this way, the light sensing element 110 operates according to the adjusted first voltage on the node N1, so that the light sensing circuit 130 generates a corresponding light sensing result DS. Therefore, based on the discharged first node N1, the sensing circuit 100 can increase the voltage difference of the light sensing result DS in applications with various light intensities, thereby improving the contrast of the image (e.g., a fingerprint image) without adjusting (e.g., increasing) the length of the exposure period.

[0072] Figure 3 is a circuit diagram of a sensing circuit according to another embodiment of the present invention. Figure 3 The sensing circuit 300 includes a light sensing element 310, a reset circuit 320, a light sensing circuit 330, a read circuit 340, and a feedback circuit 350. The light sensing element 310, the reset circuit 320, the light sensing circuit 330, the read circuit 340, and the feedback circuit 350 can refer to the relevant description of the sensing circuit 100 and be deduced by analogy.

[0073] exist Figure 3 In one embodiment, the feedback circuit 350 receives a plurality of reference voltages VREF, FVSS1 and FVSS2, and a second control signal SCAN2 (ie, Figure 1 The feedback circuit 350 is controlled by the second control signal SCAN2 to operate based on the reference voltages VREF, FVSS1 and FVSS2 and the first voltage on the first node N1.

[0074] Specifically, the feedback circuit 350 includes a plurality of transistors T1 to T3 and a plurality of capacitors C1 to C2. The transistor T1 and the capacitor C1 are connected in parallel to the second node N2 and the reference voltage FVSS2 (ie, Figure 1 The first terminal (i.e., the first source / drain terminal) of the transistor T1 and the first terminal of the capacitor C1 are both coupled to one terminal (i.e., the cathode terminal) of the light sensing element 310 at the second node N2. The second terminal (i.e., the second source / drain terminal) of the transistor T1 and the second terminal of the capacitor C1 both receive the reference voltage FVSS2. The control terminal (i.e., the gate terminal) of the transistor T1 is coupled to one terminal (i.e., the second source / drain terminal) of the transistor T2 at the third node N3.

[0075] Continuing with the above description, the control terminal (i.e., gate terminal) of transistor T2 receives the second control signal SCAN2. The other terminal (i.e., first source / drain terminal) of transistor T2 receives the reference voltage VREF (i.e., third reference voltage). The first terminal of capacitor C2 is coupled to the first node N1. The second terminal of capacitor C2 is coupled to the third node N3. The control terminal (i.e., gate terminal) of transistor T3 receives the second control signal SCAN2. The first terminal (i.e., first source / drain terminal) of transistor T3 is coupled to the second node N2. The second terminal (i.e., second source / drain terminal) of transistor T3 receives the reference voltage FVSS1 (i.e., fourth reference voltage).

[0076] In this embodiment, the reset circuit 320 receives a reference voltage FVDD (ie, Figure 1 The reset circuit 320 is controlled by the second control signal SCAN2 to operate based on the reference voltage FVDD.

[0077] Specifically, the reset circuit 320 includes a transistor T4. A control terminal (i.e., a gate terminal) of the transistor T4 receives a second control signal SCAN2. A first terminal (i.e., a first source / drain terminal) of the transistor T4 receives a reference voltage FVDD. A second terminal (i.e., a second source / drain terminal) of the transistor T4 is coupled to the first node N1.

[0078] In this embodiment, the light sensing circuit 330 receives a reference voltage FVDD. The light sensing circuit 330 is controlled by a first voltage on the first node N1 to operate based on the reference voltage FVDD. The light sensing circuit 330 is implemented as an active photo-sensing (APS) circuit, for example.

[0079] Specifically, the light sensing circuit 330 includes a transistor T5. The control terminal (i.e., gate terminal) of the transistor T5 is coupled to the first node N1. The first terminal (i.e., first source / drain terminal) of the transistor T5 receives the reference voltage FVDD. The second terminal (i.e., second source / drain terminal) of the transistor T5 is coupled to the reading circuit 340.

[0080] In this embodiment, the read circuit 340 receives the first control signal SCAN1 (ie, Figure 1 The read circuit 340 is controlled by the first control signal SCAN1 to convert the signal output by the transistor T5 (ie, Figure 1 The light sensing result DS) shown is output to the output terminal VOUT.

[0081] Specifically, the read circuit 340 includes a transistor T6. The control terminal (i.e., gate terminal) of the transistor T6 receives the first control signal SCAN1. The first terminal (i.e., first source / drain terminal) of the transistor T6 is coupled to the second terminal (i.e., second source / drain terminal) of the transistor T5. The second terminal (i.e., second source / drain terminal) of the transistor T6 is coupled to the output terminal VOUT.

[0082] Figure 4 According to the present invention Figure 3 The operation diagram of the sensing circuit of the embodiment. Figure 4 In FIG. 5 , the horizontal axis represents the operation time of the sensing circuit 300 , and the vertical axis represents the voltage value. FIG. 5A to FIG. 5C According to the present invention Figure 4 The operation schematic diagrams of the sensing circuit illustrated in the embodiment are used to illustrate the operation details of the sensing circuit 300 during the reset period PRST, the exposure period PEP and the reading period PRD respectively.

[0083] In this embodiment, transistors T1 to T6 are implemented as p-type Metal-Oxide-Semiconductor Field-Effect Transistor (PMOSFET). In other embodiments, transistors T1 to T6 are implemented as n-type Metal-Oxide-Semiconductor Field-Effect Transistor (NMOSFET). In other embodiments, the signal is inverse to the corresponding signal in this embodiment.

[0084] Also refer to Figure 4 as well as Figure 5A , the sensing circuit 300 operates in the reset period PRST. At time t1, the second control signal SCAN2 switches from the voltage value V1 to the voltage value V2 and generates a falling edge to start the reset period PRST. At time t2, the second control signal SCAN2 switches from the voltage value V2 to the voltage value V1 and generates a rising edge to end the reset period PRST. During the reset period PRST, the first control signal SCAN1 maintains the voltage value V1, and the second control signal SCAN2 maintains the voltage value V2.

[0085] In the present embodiment, the voltage value V1 is greater than the voltage value V2. The voltage value V1 is, for example, a logic high voltage value. The voltage value V2 is, for example, a logic low voltage value. In the present embodiment, the reference voltage FVDD (i.e., the first reference voltage) is, for example, a high power supply voltage. The reference voltage FVSS2 (i.e., the second reference voltage), the reference voltage VREF (i.e., the third reference voltage), and the reference voltage FVSS1 (i.e., the fourth reference voltage) are, for example, different low power supply voltages.

[0086] It should be noted that the voltage value of the reference voltage FVSS2 is lower than the voltage value of the reference voltage FVSS1 .

[0087] During the reset period PRST (ie, time t1 to t2), the transistor T6 is turned off according to the first control signal SCAN1 having a voltage value V1, and the transistors T2, T3, and T4 are turned on according to the second control signal SCAN2 having a voltage value V2.

[0088] Continuing the above description, since the transistor T2 is turned on, the voltage at the third node N3 is pulled to the reference voltage VREF through the transistor T2. In this way, the transistor T1 is turned on based on the reference voltage VREF. Since the transistor T4 is turned on, the first voltage at the first node N1 is pulled to the reference voltage FVDD through the transistor T4. In this way, the transistor T5 is turned off based on the reference voltage FVDD. In addition, since the transistor T3 is turned on, the voltage at the second node N2 is pulled to the reference voltage FVSS1 through the transistor T3.

[0089] Also refer to Figure 4 as well as Figure 5B , the sensing circuit 300 operates in the exposure period PEP. At time t2, the second control signal SCAN2 switches from the voltage value V2 to the voltage value V1 and generates a rising edge to start the exposure period PEP. At time t3, the first control signal SCAN1 switches from the voltage value V1 to the voltage value V2 and generates a falling edge to end the exposure period PEP. During the exposure period PEP, the first control signal SCAN1 and the second control signal SCAN2 both maintain the voltage value V1.

[0090] During the exposure period PEP (ie, time t2 to t3), the transistor T6 is turned off according to the first control signal SCAN1 having the voltage value V1. The transistors T2, T3, and T4 are turned off according to the second control signal SCAN2 having the voltage value V1.

[0091] Continuing with the above description, since the light sensing element 310 performs light sensing, the first voltage on the first node N1 is the voltage difference generated by the reference voltage FVDD minus the light sensing element 310. Thus, the transistor T5 is turned on based on the first voltage on the first node N1.

[0092] In addition, the voltage difference generated at the first node N1 is coupled to the third node N3 through the capacitor C2, so that the voltage at the third node N3 is the reference voltage VREF minus the voltage difference generated by the light sensing element 310. In this way, the transistor T1 is slowly turned on based on the voltage at the third node N3 to discharge the capacitor C1 and gradually pull down the voltage at the second node N2 to the reference voltage FVSS2. In other words, the first voltage at the first node N1 is pulled down through the transistor T1 and the capacitor C1.

[0093] It should be noted that during the exposure period PEP (i.e., time t2 to t3), two terminals of the light sensing element 310, the first terminal (i.e., the first source / drain terminal) and the second terminal (i.e., the second source / drain terminal) of the transistor T1, and two terminals of the capacitor C1 form a conductive transmission path and are all coupled to this transmission path. Since the transmission path formed between the first node N1 and the reference voltage FVSS2 is conductive through the feedback circuit 350, the first node N1 can be discharged through this transmission path.

[0094] In the aforementioned transmission path, the control terminal (i.e., gate terminal) of the transistor T1 is coupled to the anode terminal of the light sensing element 310 at the first node N1 through the capacitor C2. The first terminal (i.e., first source / drain terminal) of the transistor T1 and the first terminal of the capacitor C1 are coupled to the cathode terminal of the light sensing element 310 at the second node N2. The second terminal (i.e., second source / drain terminal) of the transistor T1 and the second terminal of the capacitor C1 receive the reference voltage FVSS2.

[0095] In the present embodiment, since the voltage value of the reference voltage FVSS2 is lower than the voltage value of the reference voltage FVSS, the first node N1 can be quickly discharged through the aforementioned transmission path.

[0096] Also refer to Figure 4 as well as Figure 5C , the sensing circuit 300 operates in the read period PRD. At time t3, the first control signal SCAN1 switches from the voltage value V1 to the voltage value V2 and generates a falling edge to start the read period PRD. At time t4, the first control signal SCAN1 switches from the voltage value V2 to the voltage value V1 and generates a rising edge to end the read period PRD. During the read period PRD, the first control signal SCAN1 maintains the voltage value V2, and the second control signal SCAN2 maintains the voltage value V1.

[0097] During the read period PRD (ie, time t3 to t4), the transistor T6 is turned on according to the first control signal SCAN1 having a voltage value V2, and the transistors T2, T3, and T4 are turned off according to the second control signal SCAN2 having a voltage value V1.

[0098] Continuing the above description, since the first node N1 is discharged through the transmission path of the exposure period PEP, the first voltage at the first node N1 is pulled down to a low voltage. In addition, based on the adjusted first voltage, the voltage at the third node N3 is pulled down to a low voltage through the capacitor C2. Thus, based on the voltage at the third node N3, the transistor T1 is turned on. Based on the first voltage at the first node N1, the transistor T5 is turned on.

[0099] In this embodiment, the turned-on transistor T5 generates a light sensing result based on the reference voltage FVDD according to the first voltage on the first node N1, and the turned-on transistor T6 outputs the light sensing result according to the first control signal SCAN1.

[0100] Figure 6 is a circuit diagram of a sensing circuit according to another embodiment of the present invention. Figure 6 , the sensing circuit 600 includes a light sensing element 610, a reset circuit 620, a light sensing circuit 630, a read circuit 640, and a feedback circuit 650. The light sensing element 610, the reset circuit 620, the light sensing circuit 630, the read circuit 640, and the feedback circuit 650 can refer to the relevant description of the sensing circuit 300 and be deduced by analogy.

[0101] Compared to the sensing circuit 300, Figure 6 In the embodiment, the feedback circuit 350 further includes another capacitor C3. A first terminal of the capacitor C3 is coupled to the first node N1. A second terminal of the capacitor C3 is coupled to the second node N2.

[0102] In the present embodiment, the capacitor C3 coupled between the first node N1 and the second node N2 can increase the amount of stored charges of the light sensing element 610 , thereby improving the stability of the signal sensed by the light sensing element 610 .

[0103] In summary, the sensing circuit and the operating method thereof of the embodiment of the present invention can discharge the first node in a positive feedback manner through the circuit design of the feedback circuit. Based on the discharged first node, the sensing circuit can increase the voltage difference of the light sensing result without adjusting (for example, increasing) the length of the exposure period. Therefore, in applications with various light intensities, the sensing circuit can improve the contrast of the image (for example, the fingerprint image), thereby improving the accuracy of the fingerprint recognition function.

[0104] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Any person having ordinary knowledge in the technical field may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the attached patent application.

Claims

1. A sensing circuit, characterized in that: include: a light sensing element; a reset circuit coupled to the light sensing element; a light sensing circuit coupled to the light sensing element and the reset circuit at a first node, for generating a light sensing result based on a first reference voltage according to a first voltage at the first node; a reading circuit, coupled to the light sensing circuit, for outputting the light sensing result according to a first control signal; as well as A feedback circuit is coupled to the first node to form a transmission path between the first node and a second reference voltage during an exposure period, and conducts the transmission path according to a second control signal to discharge the first node to adjust the first voltage.

2. The sensing circuit according to claim 1, wherein: During the exposure period, two terminals of the light sensing element, a first terminal and a second terminal of a first transistor in the feedback circuit, and two terminals of a first capacitor in the feedback circuit are coupled to the transmission path.

3. The sensing circuit according to claim 2, wherein: The control end of the first transistor is coupled to the anode end of the light sensing element at the first node through a second capacitor, the first end of the first transistor and the first end of the first capacitor are coupled to the cathode end of the light sensing element at a second node, and the second end of the first transistor and the second end of the first capacitor receive the second reference voltage.

4. The sensing circuit according to claim 1, wherein: The feedback circuit includes: A first transistor having a first terminal coupled to one terminal of the light sensing element at a second node, and a second terminal of the first transistor receiving the second reference voltage; a first capacitor having a first terminal coupled to the second node, and a second terminal of the second capacitor receiving the second reference voltage; A second transistor having a control terminal for receiving the second control signal, a first terminal of the second transistor for receiving a third reference voltage, and a second terminal of the second transistor coupled to the control terminal of the first transistor at a third node; a second capacitor having a first end coupled to the first node and a second end coupled to the third node; A third transistor has a control terminal for receiving the second control signal, a first terminal of the third transistor is coupled to the second node, and a second terminal of the third transistor receives a fourth reference voltage.

5. The sensing circuit according to claim 4, characterized in that: The voltage value of the second reference voltage is lower than the voltage value of the fourth reference voltage.

6. The sensing circuit according to claim 4, characterized in that: The feedback circuit also includes: A third capacitor has a first terminal coupled to the first node, and a second terminal coupled to the second node.

7. The sensing circuit according to claim 4, characterized in that: The reset circuit includes: A fourth transistor has a control terminal for receiving the second control signal, a first terminal of the fourth transistor for receiving the first reference voltage, and a second terminal of the fourth transistor coupled to the first node.

8. The sensing circuit according to claim 7, characterized in that: The light sensing circuit includes: A fifth transistor has a control terminal coupled to the first node, a first terminal of the fifth transistor receives the first reference voltage, and a second terminal of the fifth transistor is coupled to the read circuit.

9. The sensing circuit according to claim 8, characterized in that: The reading circuit includes: A sixth transistor has a control terminal for receiving the first control signal, and a first terminal of the sixth transistor is coupled to the second terminal of the fifth transistor.

10. The sensing circuit according to claim 9, characterized in that: During a reset period, the sixth transistor is turned off according to the first control signal, the second transistor, the third transistor and the fourth transistor are turned on according to the second control signal, and the first transistor and the fifth transistor are turned on.

11. The sensing circuit according to claim 9, characterized in that: During the exposure period, the sixth transistor is turned off according to the first control signal, the first transistor is turned on according to the voltage on the third node, the second transistor, the third transistor and the fourth transistor are turned off according to the second control signal, and the fifth transistor is turned on according to the first voltage.

12. The sensing circuit according to claim 9, wherein: During a reading period, the sixth transistor is turned on according to the first control signal, the second transistor, the third transistor, and the fourth transistor are turned off according to the second control signal, and the first transistor and the fifth transistor are turned on.

13. A method for operating a sensing circuit, characterized in that: include: Generate a light sensing result based on a first reference voltage according to a first voltage on a first node through a light sensing circuit, wherein the light sensing circuit is coupled to a light sensing element and a reset circuit on the first node; Outputting the light sensing result according to a first control signal through a reading circuit, wherein the reading circuit is coupled to the light sensing circuit and; A transmission path is formed between the first node and a second reference voltage during an exposure period through a feedback circuit coupled to the first node, and the transmission path is turned on according to a second control signal to discharge the first node to adjust the first voltage.

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