Optical sensor

Abstract

The invention provides an optical sensor. The optical sensor includes a photodiode and a differential current integrator. The differential current integrator comprises a first input end, a second input end, a first output end and a second output end. The first input end of the differential current integrator is connected with the photodiode. A second input terminal of the differential current integrator is coupled to a first reference voltage.

Description

Technical Field

[0001] The present invention relates to a sensor, and in particular to an optical sensor. Background Art

[0002] Optical sensors, such as proximity sensors and ambient light sensors, are used to detect changes in light and convert them into electrical signals for processing by other circuit components. However, conventional optical sensors fail to accurately detect light irradiated on the conventional optical sensors. Summary of the invention

[0003] An object of the present invention is to provide an optical sensor to solve at least one of the above problems.

[0004] In view of the shortcomings of the prior art, an optical sensor of the present invention is provided. The optical sensor of the present invention comprises a photodiode and a differential current integrator. The differential current integrator comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal. The first input terminal of the differential current integrator is connected to the photodiode. The second input terminal of the differential current integrator is coupled to a first reference voltage.

[0005] As described above, the present invention provides an optical sensor. The optical sensor of the present invention can detect light to generate a positive output voltage signal and a negative output voltage signal to suppress the common mode noise introduced in the first output terminal and the second output terminal of the differential current integrator. The optical sensor of the present invention includes two output terminals, which are respectively used to output the positive output voltage signal and the negative output voltage signal.

[0006] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 FIG. 4 is a circuit diagram of an optical sensor according to a first embodiment of the present invention.

[0008] Figure 2 An example of a signal waveform of the optical sensor of the first embodiment of the present invention is shown.

[0009] Figure 3 FIG. 4 is a circuit diagram of an optical sensor according to a second embodiment of the present invention.

[0010] Figure 4 FIG. 1 is a schematic diagram of the flow of current in an optical sensor according to a second embodiment of the present invention.

[0011] Figure 5 An example of a signal waveform of the optical sensor of the second embodiment of the present invention is shown.

[0012] Figure 6 and Fig. 6A Examples of voltage waveforms of the optical sensors according to the first and second embodiments of the present invention and a conventional optical sensor are shown.

[0013] Figure 7 An example of the waveform of the noise signal of the optical sensor according to the second embodiment of the present invention is shown. DETAILED DESCRIPTION

[0014] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0015] Figure 1 FIG. 4 is a circuit diagram of an optical sensor according to a first embodiment of the present invention.

[0016] like Figure 1 As shown, the optical sensor may include a photodiode PD and a differential current integrator DCI. The differential current integrator DCI may include a first input terminal, a second input terminal, a first output terminal, and a second output terminal. The first input terminal of the differential current integrator DCI may be connected to the photodiode PD. The second input terminal of the differential current integrator DCI may be coupled to a first reference voltage Vref1. The optical sensor may further include a photocurrent switch SP1, a first switch SW1, a switch circuit AUX, a comparator circuit CMPR, and a controller CTR.

[0017] The anode of the photodiode PD may be grounded. The cathode of the photodiode PD is connected to the first end of the photocurrent switch SP1. The photocurrent switch SP1 is a switch.

[0018] The photodiode PD converts light irradiated on the photodiode PD into a photocurrent.

[0019] The differential current integrator DCI may include an operational amplifier OP-AMP. The operational amplifier OP-AMP may have an inverting input terminal (at Figure 1 Indicated by a minus sign "-"), non-inverting input terminal (in Figure 1The operational amplifier OP-AMP is connected to the first input terminal of the differential current integrator DCI. The non-inverting input terminal of the operational amplifier OP-AMP is connected to the second input terminal of the differential current integrator DCI. The first output terminal of the operational amplifier OP-AMP is connected to the first output terminal of the differential current integrator DCI. The second output terminal of the operational amplifier OP-AMP is connected to the second output terminal of the differential current integrator DCI.

[0020] The differential current integrator DCI may output a first output voltage signal Vout1 at a first output terminal of the differential current integrator DCI. The differential current integrator DCI may output a second output voltage signal Vout2 at a second output terminal of the differential current integrator DCI.

[0021] The first input terminal of the differential current integrator DCI may be connected to the second terminal of the photocurrent switch SP1. That is, the photocurrent switch SP1 may be connected between the photodiode PD and the first input terminal of the differential current integrator DCI.

[0022] In practice, the photocurrent switch SP1 , the first switch SW1 , the first power switch SU1 and the second power switch SU2 may each have a control terminal connected to the controller CTR or an external controller (not shown) and may be controlled by the controller CTR or the external controller.

[0023] The differential current integrator DCI may further include a first integrating capacitor Cint1 and a second integrating capacitor Cint2. The first integrating capacitor Cint1 may be connected between the first input terminal and the first output terminal of the differential current integrator DCI. For example, the first end of the first integrating capacitor Cint1 may be connected to the inverting input terminal of the operational amplifier OP-AMP. The second end of the first integrating capacitor Cint1 may be connected to the first output terminal of the operational amplifier OP-AMP.

[0024] The second integrating capacitor Cint2 may be connected between the second input terminal and the second output terminal of the differential current integrator DCI. For example, the first terminal of the second integrating capacitor Cint2 may be connected to the non-inverting input terminal of the operational amplifier OP-AMP. The second terminal of the second integrating capacitor Cint2 may be connected to the second output terminal of the operational amplifier OP-AMP.

[0025] The optical sensor further includes a first current source CS1. The first current source CS1 can be connected to the differential current integrator DCI. In some embodiments, the first current source CS1 can be connected to a first input terminal of the differential current integrator DCI. In some embodiments, the first current source CS1 can be connected to a second input terminal of the differential current integrator DCI.

[0026] The first switch SW1 may be connected between the first current source CS1 and the first input terminal of the differential current integrator DCI. For example, the first terminal of the first switch SW1 may be connected to the inverting input terminal of the operational amplifier OP-AMP. The second terminal of the first switch SW1 may be connected to the first terminal of the first current source CS1, and the second terminal of the first current source CS1 may be grounded.

[0027] The switch circuit AUX may include one or more sub-switch circuits, such as but not limited to a first sub-switch circuit AU1 and a second sub-switch circuit AU2. The first sub-switch circuit AU1 may include a first input current source CU1 and a first power switch SU1, and the second sub-switch circuit AU2 may include a second input current source CU2 and a second power switch SU2, but the present invention is not limited thereto.

[0028] A first end of the first input current source CU1 is coupled to the common voltage VDD. A second end of the first input current source CU1 is connected to a first end of the first power switch SU1. A second end of the first input current source CU1 is connected to a first input end of a differential current integrator DCI. When the first power switch SU1 is turned on, a first supply current supplied by the first input current source CU1 flows through the first power switch SU1 to the first input end of the differential current integrator DCI.

[0029] A first end of the second input current source CU2 is coupled to the common voltage VDD. A second end of the second input current source CU2 is connected to a first end of a second power switch SU2. A second end of the second power switch SU2 is connected to a first input end of a differential current integrator DCI. When the second power switch SU2 is turned on, a second supply current supplied by the second input current source CU2 flows through the second power switch SU2 to the first input end of the differential current integrator DCI.

[0030] The differential current integrator DCI may further include a first reset switch SR1 and a second reset switch SR2. The first reset switch SR1 and the second reset switch SR2 are configured to achieve a reset of the voltage of the differential current integrator DCI.

[0031] A first end of the first reset switch SR1 is connected to a first input end of the differential current integrator DCI. A second end of the first reset switch SR1 is connected to a second input end of the differential current integrator DCI.

[0032] The first end of the second reset switch SR2 is connected to the first output end of the differential current integrator DCI. The second end of the second reset switch SR2 is connected to the second output end of the differential current integrator DCI. The first reset switch SR1 and the second reset switch SR2 may each have a third end connected to the controller CTR or an external controller as a control end, and may be controlled by the controller CTR or the external controller.

[0033] When the first reset switch SR1 and the second reset switch SR2 are turned on, the voltages of the first input terminal and the second input terminal of the differential current integrator DCI are reset to the same voltage, and the voltages of the first output terminal and the second output terminal of the differential current integrator DCI are reset to the same voltage. Figure 1 In the embodiment, when the first reset switch SR1 and the second reset switch SR2 are turned on, the voltages at the first input terminal and the second input terminal of the differential current integrator DCI are both reset to be equal to the first reference voltage Vref1. The first reference voltage Vref1 can be a low voltage or a zero voltage.

[0034] The comparator circuit CMPR is connected to the first output terminal and the second output terminal of the differential current integrator DCI. The comparator circuit CMPR may include two full differential comparators, such as a first voltage comparator CM1 and a second voltage comparator CM2, but the present invention is not limited thereto.

[0035] The first voltage comparator CM1 may have a first input terminal (eg, an inverting input terminal), a second input terminal (eg, a non-inverting input terminal), a third input terminal (eg, a non-inverting input terminal), and a fourth input terminal (eg, an inverting input terminal), but the present invention is not limited thereto.

[0036] The first input terminal of the first voltage comparator CM1 is connected to the second output terminal of the differential current integrator DCI. The second input terminal of the first voltage comparator CM1 is connected to the first output terminal of the differential current integrator DCI. The third input terminal of the first voltage comparator CM1 is coupled to the second reference voltage Vref2. The fourth input terminal of the first voltage comparator CM1 is coupled to the third reference voltage Vref3.

[0037] The second voltage comparator CM2 may have a first input terminal (e.g., a non-inverting input terminal), a second input terminal (e.g., an inverting input terminal), a third input terminal (e.g., a non-inverting input terminal), and a fourth input terminal (e.g., an inverting input terminal), but the present invention is not limited thereto. The first input terminal of the second voltage comparator CM2 is connected to the second output terminal of the differential current integrator DCI. The second output terminal of the second voltage comparator CM2 is connected to the first output terminal of the differential current integrator DCI. The third input terminal of the second voltage comparator CM2 is coupled to the third reference voltage Vref3. The fourth input terminal of the second voltage comparator CM2 is coupled to the second reference voltage Vref2. The output terminal of the first voltage comparator CM1 and the output terminal of the second voltage comparator CM2 are connected to the controller CTR.

[0038] Figure 2 FIG. 2 shows an example of a signal waveform of the optical sensor according to the first embodiment of the present invention. Figure 2As shown, when the photocurrent switch SP1 is turned on (by the controller CTR or an external controller), the first output voltage signal Vout1 gradually increases and the second output voltage signal Vout2 gradually decreases.

[0039] The first output voltage signal Vout1 can be calculated by the following equation:

[0040]

[0041] Wherein Vout1 is the first output voltage signal, Vcm is the common mode voltage, CT1 is the capacitance value of the first integral capacitor Cint1, and Iph is the current generated by the photodiode PD.

[0042] The second output voltage signal Vout2 can be calculated by the following equation:

[0043]

[0044] Wherein Vout2 is the second output voltage signal, Vcm is the common mode voltage, CT2 is the capacitance value of the second integral capacitor Cint2, and Iph is the current generated by the photodiode PD. In some embodiments, the capacitance value CT1 of the first integral capacitor Cint1 and the capacitance value CT2 of the second integral capacitor Cint2 are the same as each other and are the same as a capacitance value CT, which is expressed as: CT1=CT2=CT.

[0045] When the first reset switch SR1 and the second reset switch SR2 are ( Figure 1 When the controller CTR shown in the figure or an external controller not shown in the figure is turned on, the first output voltage signal Vout1 and the second output voltage signal Vout2 are reset to be the same as each other.

[0046] The first voltage comparator CM1 of the comparator circuit CMPR may compare a first voltage difference between the first output voltage signal Vout1 and the second output voltage signal Vout2 with a second voltage difference between the second reference voltage Vref2 and the third reference voltage Vref3 to output a first comparison signal.

[0047] The voltage of the first output voltage signal Vout1 is subtracted from the voltage of the second output voltage signal Vout2 to obtain a first voltage difference Vd1, as shown in the following equation:

[0048]

[0049] Wherein Vd1 is the first voltage difference, Vout1 is the first output voltage signal, Vout2 is the second output voltage signal, CT is the capacitance value of the first integral capacitor Cint1 or the second integral capacitor Cint2, and Iph is the current generated by the photodiode PD.

[0050] The second reference voltage Vref2 may be higher than the third reference voltage Vref3. The voltage of the second reference voltage Vref2 may be subtracted from the third reference voltage Vref3 to obtain a second voltage difference Vd2, as shown in the following equation:

[0051] Vd2=Vref2–Vref3,

[0052] Wherein Vd2 is the second voltage difference, Vref2 is the second reference voltage, and Vref3 is the third reference voltage.

[0053] For example, when the first voltage difference Vd1 is higher than the second voltage difference Vd2, the first voltage comparator CM1 outputs a high-level first comparison signal. Conversely, when the first voltage difference Vd1 is lower than the second voltage difference Vd2, the first voltage comparator CM1 outputs a low-level first comparison signal.

[0054] The second voltage comparator CM2 of the comparator circuit CMPR may compare a third voltage difference between the first output voltage signal Vout1 and the second output voltage signal Vout2 with a fourth voltage difference between the second reference voltage Vref2 and the third reference voltage Vref3 to output a second comparison signal.

[0055] The second output voltage signal Vout2 can be subtracted from the first output voltage signal Vout1 to obtain a third voltage difference Vd3, as shown in the following equation:

[0056]

[0057] Wherein Vd3 is the third voltage difference, Vout2 is the second output voltage signal, Vout1 is the first output voltage signal, CT is the capacitance value of the first integral capacitor Cint1 or the second integral capacitor Cint2, and Iph is the current generated by the photodiode PD.

[0058] The third reference voltage Vref3 can be subtracted from the second reference voltage Vref2 to obtain a fourth voltage difference Vd4, as shown in the following equation:

[0059] Vd4=Vref3–Vref2,

[0060] Wherein Vd4 is the fourth voltage difference, Vref3 is the third reference voltage, and Vref2 is the second reference voltage.

[0061] For example, when the third voltage difference Vd3 is higher than the fourth voltage difference Vd4, the second voltage comparator CM2 outputs a high-level second comparison signal. Conversely, when the third voltage difference Vd3 is lower than the fourth voltage difference Vd4, the second voltage comparator CM2 outputs a low-level second comparison signal.

[0062] like Figure 2 As shown, when the photocurrent switch SP1 is ( Figure 1 After the controller CTR shown in the figure or an external controller not shown in the figure) is turned on for a long time to measure the current generated by the photodiode PD, ( Figure 1 The controller CTR shown in the figure or an external controller not shown in the figure) turns off the photocurrent switch SP1 and turns on the first power switch SU1. As a result, the first output voltage signal Vout1 gradually decreases and the second output voltage signal Vout2 gradually increases.

[0063] like Figure 2 As shown, in the first power switch SU1 is ( Figure 1 After the controller CTR shown in the figure or the external controller not shown in the figure) is turned off, ( Figure 1 The controller CTR shown in the figure or an external controller not shown in the figure) turns on the first switch SW1. Therefore, the current flows from the first input terminal of the differential current integrator DCI through the first current source CS1 to the ground. In other words, the current flows out of the differential current integrator DCI. The first switch SW1 is turned on to allow the current to flow through the first current source CS1 and adjust the initial values ​​of the first output voltage signal Vout1 and the second output voltage signal Vout2. Once the first output voltage signal Vout1 and the second output voltage signal Vout2 are adjusted to the required initial values, the optical sensor can continue to measure the current generated by the photodiode PD.

[0064] The current of the first current source CS1 can be changed according to the first reference voltage Vref1. For example, the first reference voltage Vref1 can be adjusted in the range of 0V to 0.3V. For example, if the first reference voltage Vref1 is adjusted in the range of 0V to 0.3V, the first current source CS1 can supply a current with a desired current value of 3nA. If the first reference voltage Vref1 is 0.1V, the first current source CS1 can supply a current with a current value much smaller than the desired value, such as 0.17nA. Therefore, in some embodiments, the first reference voltage Vref1 can be greater than or equal to 0.2V.

[0065] The controller CTR may receive and store a first comparison signal received from the output terminal of the first voltage comparator CM1 and a second comparison signal received from the output terminal of the second voltage comparator CM2. The controller CTR or an external controller (not shown) may control the operation of the photocurrent switch SP1, the first switch SW1, the first power switch SU1, the second power switch SU2, the first reset switch SR1, and the second reset switch SR2 according to the first comparison signal and the second comparison signal.

[0066] Figure 3 2 is a circuit diagram of an optical sensor according to a second embodiment of the present invention. The same contents of the second embodiment of the present invention as those of the first embodiment of the present invention will not be described in detail herein.

[0067] A difference between the second embodiment of the present invention and the first embodiment is that the optical sensor of the second embodiment of the present invention includes a reference voltage switching circuit VREFSWAP. Figure 3 It is shown that the common voltage VDD can supply current for the first current source CS1, the first input current source CU1 and the second input current source CU2. Another difference between the second embodiment of the present invention and the first embodiment is that in the second embodiment, when the first switch SW1 is turned on, the current flows from the common voltage VDD through the first current source CS1 to the second input terminal of the differential current integrator DCI. In other words, the current flows to the differential current integrator DCI.

[0068] like Figure 3 As shown, the reference voltage exchange circuit VREFSWAP includes a second switch SW2 and a third switch SW3. The first switch SW1 is connected between the first current source CS1 and the second input terminal of the differential current integrator DCI. The second switch SW2 is connected between the first reference voltage Vref1 and the first input terminal of the differential current integrator DCI. The third switch SW3 is connected between the first reference voltage Vref1 and the second input terminal of the differential current integrator DCI.

[0069] In detail, the first terminal of the first current source CS1 is coupled to the common voltage VDD, or is connected to the positive terminal of the input power source for supplying the common voltage VDD.

[0070] The second end of the first current source CS1 is connected to the first end of the first switch SW1. The second end of the first switch SW1 is connected to the second input end of the differential current integrator DCI.

[0071] The first end of the second switch SW2 is coupled to the first reference voltage Vref1. The second end of the second switch SW2 is connected to the first input end of the differential current integrator DCI. The first end of the third switch SW3 is coupled to the second input end of the differential current integrator DCI. The second end of the third switch SW3 is coupled to the first reference voltage Vref1. The second switch SW2 and the third switch SW3 each have a third end as a control end, and the control end is connected to the controller CTR or an external controller. The second switch SW2 and the third switch SW3 can be controlled by the controller CTR or the external controller.

[0072] like Figure 3 As shown, the first switch SW1 and the second switch SW2 may be closed, and the third switch SW3 may be opened. Therefore, the first current source CS1 may not be able to supply current, and the first reference voltage Vref1 may be coupled to the second input terminal of the differential current integrator DCI through the third switch SW3.

[0073] Figure 4 FIG. 2 is a schematic diagram of the flow of current in the optical sensor of the second embodiment of the present invention. Figure 4 As shown, when the first switch SW1 is turned on, the current supplied by the first current source CS1 flows through the first switch SW1 to the second input terminal of the differential current integrator DCI.

[0074] In the reference voltage exchange circuit VREFSWAP, the second switch SW2 and the third switch SW3 can be turned on alternately, so that the first reference voltage Vref1 is alternately supplied to the first input terminal and the second input terminal of the differential current integrator DCI. Alternatively, if the first current source CS1 is required to provide current, the second switch SW2 and the third switch SW3 can also be turned on. For example, the first switch SW1 and the second switch SW2 can be turned on, and the third switch SW3 can be turned off.

[0075] Figure 5 FIG. 2 shows an example of a signal waveform of an optical sensor according to a second embodiment of the present invention. Figure 5 As shown, when the reference voltage exchange indication signal SWPS has a low voltage, the first switch SW1 and the second switch SW2 can be closed, and the third switch SW3 can be opened. Therefore, the first current source CS1 cannot supply current, the current of the first current source CS1 is zero, and the first reference voltage Vref1 is coupled to the second input terminal of the differential current integrator DCI through the third switch SW3. When the reference voltage exchange indication signal SWPS has a high voltage, the first switch SW1 and the second switch SW2 can be opened, and the third switch SW3 can be closed.

[0076] Therefore, the first current source CS1 can supply current, and the first reference voltage Vref1 is coupled to the first input terminal of the differential current integrator DCI through the second switch SW2. In some embodiments, the first reference voltage Vref1 can be zero. In other words, the first reference voltage Vref1 can be grounded. Figure 5 As shown, the first current source CS1 supplies a current having a desired current value of 3 nA. Therefore, if the first reference voltage Vref1 is a low voltage, the first current source CS1 works normally.

[0077] For example, Figure 5 As shown, when the first switch SW1 is turned on, the first reference voltage Vref1 is zero, and the current supplied by the first current source CS1 reaches an absolute value of “3 nA”, but the present invention is not limited thereto.

[0078] Figure 6 and Fig. 6A Examples of voltage waveforms of the optical sensors according to the first and second embodiments of the present invention and a conventional optical sensor are shown.

[0079] For example, the common mode voltage of the common mode noise signal CMNS may have an average voltage value of “0.3V”, a voltage variation of 10 mV, and a frequency of 10 MHz.

[0080] In a conventional optical sensor, the current integrator includes only a single output terminal, and includes only a capacitor and a switch, wherein the capacitor and the switch are connected between a first input terminal (eg, an inverting input terminal) of the conventional optical sensor and the single output terminal.

[0081] Therefore, if Figure 6 As shown, when the conventional optical sensor detects light, the conventional optical sensor outputs a voltage output signal TGS0, which only includes positive voltages but not negative voltages. Furthermore, the voltage variation range of the voltage output signal TGS0 output by the current integrator of the conventional optical sensor is only a small voltage range.

[0082] In contrast, the differential current integrator DCI outputs a first output voltage signal Vout1 and a second output voltage signal Vout2 .

[0083] Therefore, when the optical sensor of the present invention detects light, the optical sensor of the present invention outputs a voltage output signal TGS1. The voltage output signal TGS1 can be a first voltage difference Vd1, calculated by the following equation:

[0084]

[0085] The voltage variation range of the voltage output signal TGS1 of the optical sensor of the present invention is much greater than that of the voltage output signal TGS0 of the conventional optical sensor. For example, the voltage range of the voltage output signal TGS1 can be twice as large as that of the voltage output signal TGS0 which only has a positive voltage.

[0086] Furthermore, a common mode noise signal CMNS may be applied at the input of the optical sensor. Fig. 6A As shown, the voltage output signal TGS1 of the optical sensor of the present invention changes by only about 2.14 mV between the peak value "600.45406 mV" and the valley value "598.31465 mV".

[0087] In contrast, the voltage output signal TGS0 of the conventional optical sensor has a voltage variation of 18.3 mV between the peak value “608.19553 mV” and the valley value “589.9045 mV”.

[0088] Therefore, the optical sensor of the present invention has a higher common mode noise immunity than the conventional optical detector. As a result, the optical sensor of the present invention can detect the intensity of light more accurately than the conventional optical sensor.

[0089] Figure 7 An example of the waveform of the noise signal of the optical sensor according to the second embodiment of the present invention is shown.

[0090] Figure 7 1 shows an example of noise signals NS1 and NS0. The noise signal NS1 is the noise at the output of the differential current integrator DCI when the first reference voltage Vref1 is zero. In other words, the node of the first reference voltage Vref1 is grounded. The noise signal NS0 is the noise at the output of the differential current integrator DCI when another analog reference buffer circuit generates the first reference voltage Vref1. Another analog reference buffer circuit supplies a non-zero voltage to the differential current integrator DCI. Figure 7 As shown, the variable AM1 of the noise signal NS1 is much smaller than the variable AM0 of the noise signal NS0. Obviously, when the first reference voltage Vref1 is zero, the noise generated by the optical sensor of the present invention is significantly reduced. In addition, reducing the first reference voltage Vref1 to a low voltage can reduce the dark current of the photodiode PD.

[0091] In summary, the optical sensor of the present invention can detect light to generate a first output voltage signal Vout1 and a second output voltage signal Vout2 to suppress the common mode noise introduced at the first output terminal and the second output terminal of the differential current integrator. The optical sensor of the present invention can output a voltage output signal TGS1 based on the first output voltage signal Vout1 and the second output voltage signal Vout2. The voltage variation range of the voltage output signal TGS1 of the optical sensor of the present invention is much larger than the voltage variation range of the voltage output signal TGS0 of the conventional optical sensor.

[0092] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the claims of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention description and drawings are included in the claims of the present invention.

Claims

1. An optical sensor, characterized in that: The optical sensor comprises: Photodiode; as well as The differential current integrator comprises a first input terminal, a second input terminal, a first output terminal and a second output terminal, wherein the first input terminal of the differential current integrator is connected to the photodiode, and the second input terminal of the differential current integrator is coupled to a first reference voltage.

2. The optical sensor according to claim 1, characterized in that The optical sensor further comprises: A first current source is connected to the differential current integrator.

3. The optical sensor according to claim 2, characterized in that The first current source is connected to the first input terminal of the differential current integrator.

4. The optical sensor according to claim 3, characterized in that The optical sensor further comprises: The first switch is connected between the first current source and the first input terminal of the differential current integrator.

5. The optical sensor according to claim 1, characterized in that The optical sensor further comprises: A first voltage comparator, wherein the first input terminal of the first voltage comparator is connected to the second output terminal of the differential current integrator, the second input terminal of the first voltage comparator is connected to the first output terminal of the differential current integrator, the third input terminal of the first voltage comparator is coupled to a second reference voltage, and the fourth input terminal of the first voltage comparator is coupled to a third reference voltage.

6. The optical sensor according to claim 5, characterized in that The optical sensor further comprises: A second voltage comparator, wherein the first input terminal of the second voltage comparator is connected to the second output terminal of the differential current integrator, the second input terminal of the second voltage comparator is connected to the first output terminal of the differential current integrator, the third input terminal of the second voltage comparator is coupled to the third reference voltage, and the fourth input terminal of the second voltage comparator is coupled to the second reference voltage.

7. The optical sensor according to claim 1, characterized in that The differential current integrator comprises: an operational amplifier, having an inverting input terminal, a non-inverting input terminal, a first output terminal and a second output terminal, wherein the inverting input terminal of the operational amplifier is connected to the first input terminal of the differential current integrator, the non-inverting input terminal of the operational amplifier is connected to the second input terminal of the differential current integrator, the first output terminal of the operational amplifier is connected to the first output terminal of the differential current integrator, and the second output terminal of the operational amplifier is connected to the second output terminal of the differential current integrator; a first integrating capacitor connected between the first input terminal and the first output terminal of the differential current integrator; as well as A second integrating capacitor is connected between the second input terminal and the second output terminal of the differential current integrator.

8. The optical sensor according to claim 1, characterized in that The optical sensor further comprises: A photocurrent switch is connected between the photodiode and the first input terminal of the differential current integrator.

9. The optical sensor according to claim 1, characterized in that: The optical sensor further comprises: A first input current source, wherein a first terminal of the first input current source is coupled to a common voltage; and A first power switch, wherein a first terminal of the first power switch is connected to a second terminal of the first input current source, and a second terminal of the first power switch is connected to the first input terminal of the differential current integrator.

10. The optical sensor according to claim 9, characterized in that The optical sensor further comprises: A second input current source, wherein a first terminal of the second input current source is coupled to the common voltage; and A second power switch, wherein a first terminal of the second power switch is connected to a second terminal of the second input current source, and a second terminal of the second power switch is connected to the first input terminal of the differential current integrator.

11. The optical sensor according to claim 9, characterized in that The differential current integrator comprises: a first reset switch, wherein a first end of the first reset switch is connected to the first input end of the differential current integrator, and a second end of the first reset switch is connected to the second input end of the differential current integrator; as well as A second reset switch, wherein a first end of the second reset switch is connected to the first output end of the differential current integrator, and a second end of the second reset switch is connected to the second output end of the differential current integrator.

12. The optical sensor according to claim 9, characterized in that The first input current source is connected to the second input terminal of the differential current integrator.

13. The optical sensor according to claim 2, characterized in that The optical sensor further comprises: The first switch is connected between the first current source and the second input terminal of the differential current integrator.

14. The optical sensor according to claim 13, characterized in that The optical sensor further comprises: The second switch is connected between the first reference voltage and the first input terminal of the differential current integrator.

15. The optical sensor according to claim 14, characterized in that The optical sensor further comprises: A third switch is connected between the first reference voltage and the second input terminal of the differential current integrator.

16. The optical sensor according to claim 15, characterized in that The first reference voltage is zero.

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