CN104079270A - Electronic device and comparator thereof - Google Patents

Abstract

The invention discloses an electronic device and a comparator thereof. The sampling unit selectively samples the first input signal and the second input signal and generates a difference signal. The amplifying unit receives the difference signal and generates an output signal, wherein the amplifying unit is driven by a first preset voltage, a second preset voltage, a first system supply voltage and a second system supply voltage. The first preset voltage is used for setting an operating point of the amplifying unit, and the second preset voltage is greater than the first system supply voltage.

Description

Electronic device and its comparator

technical field

The present invention relates to an electronic device, and more particularly to a comparator.

Background technique

Comparators are often used in various sensing applications, such as sensing circuits of touch panels and the like. The comparator is used for comparing the input signal with the reference voltage to generate a comparison result.

At present, the common comparators are mostly realized by means of complementary metal oxide semiconductor (CMOS). However, the structure of the comparator realized by CMOS usually utilizes P-type transistors and N-type transistors, so more cumbersome manufacturing procedures are required, which increases the cost. In addition, if the manufacturing process of the CMOS varies, the operation of the comparator may be disabled or a wrong comparison result may be generated.

Therefore, how to effectively reduce the manufacturing cost and operational reliability of the comparator is one of the current important research and development topics, and has also become an urgent need for improvement in related fields.

Contents of the invention

An aspect of the present invention is to provide an electronic device. The electronic device includes a sampling unit and an amplification unit. The sampling unit is used for selectively sampling the first input signal and the second input signal, and generating a difference signal. The amplifying unit is used for receiving the difference signal and generating an output signal, wherein the amplifying unit is driven by the first preset voltage, the second preset voltage, the first system supply voltage and the second system supply voltage. The first preset voltage is used to set the operating point of the amplifying unit, and the second preset voltage is greater than the first system supply voltage.

To sum up, the electronic device disclosed in the disclosure can effectively improve the operation reliability through various voltage setting methods under process variation.

Description of drawings

In order to make the above and other objects, features, advantages and embodiments of the present invention more comprehensible, the accompanying drawings are described as follows:

FIG. 1A is a schematic diagram illustrating a comparator according to an embodiment of the present invention;

FIG. 1B is an operation timing diagram illustrating the comparator in FIG. 1A according to an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating an amplification unit according to an embodiment of the present invention;

FIG. 3A is a schematic diagram illustrating an amplification unit according to an embodiment of the present invention;

3B is a graph showing the relationship between the voltage gain and the difference signal of the amplifying unit in FIG. 3A before the preset voltage is adjusted according to an embodiment of the present invention;

3C is a graph showing the relationship between the voltage gain Q and the difference signal of the amplifying unit in FIG. 3A after the preset voltage is adjusted according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating an amplification unit according to an embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating the application of a light sensing system according to an embodiment of the present invention; and

FIG. 6 is a schematic diagram illustrating the application of a Hall sensing device according to an embodiment of the disclosure.

In order to make the content of the present invention more obvious and easy to understand, the description of the attached symbols is as follows:

100: Comparator 140, 200, 300, 400: Amplifying unit

VIN1, VIN2: input signal VC1, VC2: control signal

VSIG: difference signal α: offset value

VINIT, VCC, VEE: preset voltage 501, 502: light sensor

T1, T2, T3, T4, T5, T6, SW1, SW2, SW3: switch

VCC1, VINIT1, VEE1, VS1, VS3: voltage 120: sampling unit

142: Amplifying circuit VOUT: output signal

Q: Voltage gain A, B: Node

VDD, VSS: system supply voltage Light sensing device: 500

Mask: 503 Hall sensing device: 600

Hall element: 601 C: capacitor

IDS1, IDS2, IDS3, IDS4, IDS6, IF1, IF2: Current

Detailed ways

The following examples are described in detail with reference to the accompanying drawings, but the provided examples are not intended to limit the scope of the present invention, and the description of structural operations is not intended to limit the order of execution, any structure recombined by components, The resulting devices with equivalent functions are within the scope of the present invention. In addition, the drawings are for illustration purposes only and are not drawn to original scale. For ease of understanding, the same components will be described with the same symbols in the following description.

In addition, as used herein, "coupling" or "connection" may refer to two or more elements being in direct physical or electrical contact with each other, or indirect physical or electrical contact with each other, or referring to two or more components. Multiple elements operate or act on each other.

Please refer to FIG. 1A , which is a schematic diagram of a comparator 100 according to an embodiment of the present invention. As shown in FIG. 1A , the comparator 100 includes a sampling unit 120 and an amplifying unit 140 . The sampling unit 120 is used for selectively sampling the input signal VIN1 and the input signal VIN2 to generate a difference signal VSIG. The amplifying unit 140 is electrically coupled to the sampling unit 120 and used for receiving the difference signal VSIG to generate an output signal VOUT.

In various embodiments of the present invention, the amplifying unit 140 is configured to be driven by the preset voltage VINIT, the preset voltage VCC, the system supply voltage VDD and the system supply voltage VSS. The aforementioned preset voltage VINIT can be used to set the operating point of the amplifying unit 140 , wherein the preset voltage VCC is set higher than the system supply voltage VDD, and the system supply voltage VDD is set higher than the system supply voltage VSS. With the above configuration, when the internal components of the amplifying unit 140 vary due to process errors or long-term use, the preset voltage VINIT and the preset voltage VCC can be adjusted up or down accordingly, so as to reduce the variation of the internal components. Influence. In this way, the operation reliability of the amplifying unit 140 is improved. The relevant operations here will be described in detail in the subsequent paragraphs.

As shown in FIG. 1A , in some embodiments, the sampling unit 120 includes a switch SW1 , a switch SW2 and a capacitor C. As shown in FIG. The first terminal of the switch SW1 is used for receiving the input signal VIN1 , and the control terminal of the switch SW1 is used for receiving the control signal VC1 . The first terminal of the switch SW2 is used to receive the input signal VIN2 , and the control terminal of the switch SW2 is used to receive the control signal VC2 , wherein the above-mentioned control signal VC1 and the control signal VC2 are set to be opposite phases. The first end of the capacitor C (ie, the node A) is electrically coupled to the second end of the switch SW1 and the second end of the switch SW2 .

Furthermore, the amplifying unit 140 includes a switch SW3 and an amplifying circuit 142 . The first end of the switch SW3 is electrically coupled to the second end of the capacitor C (namely the node B), the second end of the switch SW3 is used to receive the preset voltage VINIT, and the control end of the switch SW3 is used to receive the control signal VC1. The amplifying circuit 142 is electrically coupled to the first end of the switch SW3 (ie, node B), and receives the difference signal VSIG and the preset voltage VINIT according to the timing of the control signal VC1 . For example, the amplifying circuit 142 can receive the preset voltage VINIT when the switch SW3 is turned on by the control signal VC1, and receive the superimposed signal of the difference signal VSIG and the preset voltage VINIT when the switch SW3 is turned off by the control signal VC1, and then generate output signal VOUT.

In terms of function, the switch SW1 is selectively turned on according to the control signal VC1 to transmit the input signal VIN1 to the capacitor C for storage. Likewise, the switch SW2 can be selectively turned on according to the control signal VC2 , and the input signal VIN2 is transmitted to the capacitor C for storage. The capacitor C can output the difference signal VSIG according to the stored control signal VC1 and the control signal VC2 . The switch SW3 is selectively turned on according to the control signal VC1 to transmit the predetermined voltage VINIT to the second terminal of the capacitor C, thereby adjusting the signal level of the difference signal VSIG, thereby setting the operating point of the amplifying circuit 142 .

FIG. 1B is a timing diagram illustrating the operation of the comparator 100 in FIG. 1A according to an embodiment of the disclosure. For convenience of description, please refer to FIG. 1A and FIG. 1B together.

At time T1, the control signal VC1 is switched to a high level voltage, and the switch SW1 and the switch SW3 are thus turned on. The input signal VIN1 can be transmitted to the capacitor C through the switch SW1, so that the voltage level of the node A is switched to the level of the input signal VIN1. At the same time, the predetermined voltage VINIT is transmitted to the capacitor C through the switch SW3, so that the voltage level of the node B is switched to the level of the predetermined voltage VINIT.

At time T2, the control signal VC1 is switched to a low level voltage, the switches SW1 and SW3 are thus turned off, the voltage level of the node A is still maintained at the voltage level of the input signal VIN1, and the voltage level of the node B is also maintained at The voltage level of the preset voltage VINIT.

At time T3, the control signal VC2 is switched to a high level voltage, and the switch SW2 is thus turned on. The input signal VIN2 can be transmitted to the capacitor C through the switch SW2, so that the voltage level of the node A is switched from the level of the input signal VIN1 to the level of the input signal VIN2, and the change of the potential difference is the difference signal VSIG, that is, Difference signal VSIG=VIN2-VIN1. At the same time, due to the characteristics of the capacitor C, the same potential difference will also change on the node B, and the voltage level of the node B is therefore raised from the voltage level of the preset voltage VINIT by the same potential difference (that is, approximately Amplitude of difference signal VSIG). Therefore, the amplifying circuit 142 can amplify the difference signal VSIG. If the voltage gain of the amplifying circuit 142 is Q, the difference signal VSIG can be output Q times, that is, the output signal VOUT=Q*VSIG.

As shown in FIG. 1B , if the input signal VIN2 is greater than the input signal VIN1 , the comparator 100 may output an output signal VOUT with a high level voltage. On the contrary, if the input signal VIN2 is smaller than the input signal VIN1 , the comparator 100 can output the output signal VOUT with a low level voltage. Therefore, the comparison result between the input signal VIN1 and the input signal VIN2 can be obtained through the voltage level of the output signal VOUT.

The following paragraphs of the content of the present invention will propose several embodiments, which can be used to realize the functions and operations of the amplifying unit 140 described above, but the content of the present invention is not limited to the following embodiments.

Please refer to FIG. 2 . FIG. 2 is a schematic diagram illustrating an amplification unit 200 according to an embodiment of the present invention. As shown in FIG. 2 , the amplifying circuit 142 in the amplifying unit 200 includes a switch T1 and a switch T2 . The first terminal of the switch T1 is used for receiving the system supply voltage VDD, the second terminal of the switch T1 is used for generating the output signal VOUT, and the control terminal of the switch T1 is used for receiving the preset voltage VCC. The first end of the switch T2 is electrically coupled to the second end of the switch T1, and the second end of the switch T2 is used to receive the system supply voltage VSS, that is, the output signal VOUT is electrically coupled to the second end of the switch T1 and the switch T2. The first terminal of the switch T2 is used to receive the difference signal VSIG.

In practice, the aforementioned switches T1 and T2 each have a threshold voltage VTH. Under normal operation, the preset voltage VCC is set to be a voltage VCC1 greater than the sum of the system supply voltage VDD and the threshold voltage VTH, that is, VCC=VCC1>VDD+VTH, and the preset voltage VINIT is set to the voltage VINIT1. As shown in FIG. 2 , the preset voltage VINT is applied to the control terminal of the switch T2 , thereby setting the operating point of the amplifying circuit 142 . Therefore, the value of the voltage VINIT1 can be adjusted according to the actual requirement, so as to operate the amplifying circuit 142 in a proper operating condition. When process variations or element aging cause variations in the threshold voltages VTH of the switches T1 and T2 , the reliability of the amplifying unit 140 can be improved by adjusting the preset voltage VINIT and the preset voltage VCC.

For example, the comparator 100 can be applied in a sensing circuit of a touch panel. In normal operation, through the above-mentioned voltage setting, the switch T2 operates in the saturation region, and the switch T1 operates in the linear region, so the current IDS2 of the switch T2 and the current IDS1 of the switch T1 can be expressed as the following formula (1) and formula ( 2), wherein β is the process parameter of switch T1 and switch T2:

IDS2=(β/2)×[(VINT1+VSIG-VSS)-VTH] ² …(1)

IDS1=(β/2)×[(VCC1-VOUT)-VTH-1/2(VDD-VOUT)]×(VDD-VOUT)…(2)

After the manufacture of multiple touch panels is completed, by testing each panel, it can be known whether there is variation in the components of each panel. Assume that the threshold voltage VTH of the switch T1 and the switch T2 in the sensing circuit corresponding to one of the panels is offset by a value α compared with the threshold voltage VTH of the switch T1 and the switch T2 of the other panel due to process variation, where α can be to any value. At this time, the IDS2A of the switch T2 and the current IDS1A of the switch T1 can be expressed as the following formula (3) and formula (4):

IDS2A=(β/2)×[(VINIT1+VSIG-VSS)-(VTH+α)] ² …(3)

IDS1A=(β/2)×[(VCC1-VOUT)-(VTH+α)-1/2(VDD-VOUT)]×(VDD-VOUT)…(4)

The above-mentioned offset value α can be obtained by measuring various electrical parameters (such as voltage, current, threshold voltage, etc.) of each panel by automatic test equipment. In order to prevent the voltage gain Q of the amplifying unit 120 from shifting or operating ineffective due to process variation, in this embodiment, the preset voltage VINT can be set as the sum of the voltage VINT1 and the offset value α, that is, VINT=VINT1+α, And the preset voltage VCC is set as the sum of the voltage VCC1 and the offset value α, that is, VCC=VCC1+α. Bringing the adjusted preset voltage VINT and the preset voltage VCC into the above equations (3) and (4) again, the original equations (1) and (2) can be obtained. That is to say, through the above configuration, the influence of process variation or component aging on the switch T1 and the switch T2 can be improved, so that the switch T1 and the switch T2 can maintain a stable operating current. The above operation of adjusting the voltage can be completed by automatic testing equipment or a controller, but the content of the present invention is not limited thereto.

Please refer to FIG. 3A , which is a schematic diagram illustrating an amplification unit 300 according to an embodiment of the present invention. The amplifying circuit 142 in the amplifying unit 200 of FIG. 2 is a single-stage amplifier. In some embodiments, the amplifying circuit 142 includes multi-stage cascaded amplifiers to have a higher voltage gain Q. For example, compared with the amplifying unit 200 , the amplifying unit 300 is preset to be driven by the voltage VEE, and the amplifying circuit 142 in the amplifying unit 300 further includes a switch T3 , a switch T4 , a switch T5 and a switch T6 . The switch T1 and the switch T2 constitute the first-stage amplifier, the switches T3 and the switch T4 constitute the second-stage amplifier, and the switches T5 and the switch T6 constitute the third-stage amplifier. The above is only an example, and the content of the present invention is not limited thereto. Those skilled in the art can select the corresponding structure of the amplifier circuit 142 according to the required voltage gain Q.

Specifically, the first terminal of the switch T1 is used to receive the system supply voltage VDD, and the control terminal of the switch T1 is used to receive the preset voltage VCC. The first terminal of the switch T2 is electrically coupled to the second terminal of the switch T1, and the second terminal of the switch T2 is used for receiving the system supply voltage VSS, and the control terminal of the switch T2 is used for receiving the difference signal VSIG. The first terminal of the switch T3 is used to receive the preset voltage VCC, and the control terminal of the switch T3 is also used to receive the preset voltage VCC. The first terminal of the switch T4 is electrically coupled to the second terminal of the switch T3, the second terminal of the switch T4 is used to receive the preset voltage VEE, and the control terminal of the switch T4 is electrically coupled to the second terminal of the switch T1, that is, the switch The control terminals of T4 are electrically coupled to the second terminal of the switch T1 and the first terminal of the switch T2. The first end of the switch T5 is used to receive the system supply voltage VDD, the second end of the switch T5 is used to generate the output signal VOUT, and the control end of the switch T5 is electrically coupled to the second end of the switch T3, that is, the control end of the switch T5 Both are electrically coupled to the second terminal of the switch T3 and the first terminal of the switch T4. The first terminal of the switch T6 is electrically coupled to the second terminal of the switch T5, the second terminal of the switch T6 is used to receive the preset voltage VEE, and the control terminal of the switch T6 is electrically coupled to the control terminal of the switch T4, that is, the switch T6 The control terminals of the switches are electrically coupled to the control terminal of the switch T4, the second terminal of the switch T1 and the first terminal of the switch T2.

Under normal operation, the preset voltage VEE is set to be greater than or equal to the voltage VEE1 equal to the sum of the supply voltage VSS and the threshold voltage VTH, that is, the voltage VEE1≧VSS+VTH, so that the switches T3, T4 and T6 all operate in the saturation region . Therefore, the current IDS3 of the switch T3, the current IDS4 of the switch T4, and the current IDS6 of the switch T6 can be respectively expressed as the following equations (5), (6) and (7), where β is the process parameter of the switches T1 ~ T6, VS1 VS3 is the voltage at the second terminal of switch T3:

IDS3=(β/2)×[(VCC1-VS3)-VTH] ² …(5)

IDS4=(β/2)×[(VS1-VEE1)-VTH] ² …(6)

IDS6=(β/2)×[(VS1-VEE1)-VTH] ² …(7)

If the threshold voltage VTH of multiple switches T1-T6 in the sensing circuit produces an offset value α due to process variation, then the IDS3A of the switch T3, the current IDS4A of the switch T4, and the current IDS6A flowing through the switch T6 can be respectively expressed as follows Formula (8), formula (9) and formula (10):

IDS3A=(β/2)×[(VCC1-VS3)-(VTH+α)] ² …(8)

IDS4A=(β/2)×[(VS1-VEE1)-(VTH+α)] ² …(9)

IDS6A=(β/2)×[(VS1-VEE1)-(VTH+α)] ² …(10)

Similarly, in order to avoid the influence of process variation, the preset voltage VCC can be set as the sum of the voltage VCC1 and the offset value α, that is, VCC=VCC1+α, and the preset voltage VEE can be set as the voltage VEE1 and the offset value The difference of α, ie VEE=VEE1-α. Bringing the adjusted preset voltage VCC and preset voltage VEE into the above formula (8), formula (9) and formula (10) again, the original formula (5), formula (6) and formula (7) can be obtained ).

Since the switch T1 and the switch T2 are similar to the previous amplifying unit 200 , and the relationship between their operating currents is also the same as the aforementioned equations (1) to (4), so it will not be repeated here. Through the arrangement of the above-mentioned plurality of preset voltages, the effects of variations on the switches T1 , T2 , T3 , T4 and T6 can be effectively improved.

FIG. 3B is a graph illustrating the relationship between the voltage gain Q and the difference signal VSIG of the amplifying unit 300 in FIG. 3A before the preset voltage is adjusted according to an embodiment of the disclosure. FIG. 3C is a graph illustrating the relationship between the voltage gain Q and the difference signal VSIG of the amplifying unit 300 in FIG. 3A after the preset voltage is adjusted according to an embodiment of the disclosure.

Please refer to FIG. 3A and FIG. 3B together, where it is assumed that the above offset values α are +3V, +2V, +1V, -1V, -2V and -3V respectively. As shown in FIG. 3A, before the preset voltage VINIT, the preset voltage VCC and the preset voltage VEE are not adjusted, if the plurality of switches T1-T6 vary, the voltage gain Q of the amplifying unit 300 will be about 2-10. changes. If the voltage gain Q of the amplifying unit 300 is too large, the output signal VOUT may be oversaturated, and the operation of the sensing circuit of the touch panel may fail.

On the contrary, as shown in FIG. 3C , after the preset voltages VINIT, VCC and VEE are adjusted, it can be seen that the variation range of the voltage gain Q of the amplifying unit 300 is significantly reduced due to the influence of process variation, and the voltage gain Q can be used. Stable falls in the numerical range of about 6-7.

Please refer to FIG. 4 , which is a schematic diagram illustrating an amplification unit 400 according to an embodiment of the present invention. Compared with the amplifying unit 300 in FIG. 3A , the first end of the switch T3 of the amplifying unit 400 is configured to receive the system supply voltage VDD. In this example, the switch T3 is changed to operate in the linear region to achieve the application of different voltage gains Q. Wherein, the rest of the elements in the amplifying unit 400 and their related operations are similar to the above-mentioned embodiments shown in FIG. 2 and FIG. 3A , so related descriptions are not repeated here.

If the manufacturing process varies, the current IDS3 of the switch T3 can be expressed as the following formula (11):

IDS3=(β/2)×[(VCC-VS3)-(VTH+α)-1/2(VDD-VS3)]×(VDD-VS3)…(11)

Likewise, the preset voltage VCC can be set as the sum of the voltage VCC1 and the offset value α, that is, VCC=VCC1+α, so as to reduce the variation of the current IDS3 .

It should be noted that the structure of the amplifying unit 200 , 300 or 400 only utilizes a single type of switch, so the manufacturing cost can be reduced and the yield rate can be better. Those skilled in the art can choose to use the architecture of the amplifying unit 200 , 300 or 400 according to the voltage gain or circuit cost required by actual needs. The structure of the amplifying unit 200 , 300 or 400 is just an example, and the content of the present invention is not limited thereto. Those skilled in the art can replace the internal switching elements accordingly to achieve different voltage gains.

In various embodiments of the present invention, each switch can be various types of transistors, such as metal oxide semiconductor field effect transistors (MOSFETs), bottom gate transistors, top gate transistors, thin film transistors and so on. The above are examples only, and the present invention is not limited thereto

Please refer to FIG. 5 . FIG. 5 is a schematic diagram illustrating an application of a light sensing system 500 according to an embodiment of the present invention. The comparator 100 shown in the summary of the present invention can be applied to various electronic devices, such as the sensing circuit of the aforementioned touch panel, light sensing device, Hall sensing device and other applications. For example, as shown in FIG. 5 , the light sensing device 500 includes a light sensor 501 , a light sensor 502 , a photomask 503 and a comparator 100 . The light sensor 501 and the light sensor 502 can be photodiodes, photoresistors and the like. The light sensor 501 is used to detect the light intensity of the environment to be measured to generate an input signal VIN1. The photomask 503 is disposed on the light sensor 502, so that the light sensor 502 only detects the background noise of the environment to be tested to output the input signal VIN2. In this way, by using the output signal VOUT output by the comparator 100 , the light intensity after filtering the background noise can be obtained. Wherein, the operation of the sampling unit (for example: the sampling unit 120 in FIG. 1A ) and the amplification unit (for example: the amplification unit 140 in FIG. 1A ) is the same as that of the embodiment shown in FIG. 1A , so the related description will not be repeated.

Please refer to FIG. 6 . FIG. 6 is an application schematic diagram of a Hall sensing device 600 according to an embodiment of the present invention. As shown in FIG. 6 , the Hall sensing device 600 includes a Hall element 601 and a comparator 100 . The Hall element 601 is used to generate an input signal VIN1 and an input signal VIN2 with different values according to the current IF1 and the current IF2 . When the output signal VOUT is larger, it means that the voltage difference between the input signal VIN1 and the input signal VIN2 is larger, that is, the magnetic field generated by the current IF1 and the current IF2 is larger. In this way, the strength of the magnetic field generated at both ends of the Hall element 100 can be measured by the comparator 100 . Wherein, the operation of the sampling unit (for example: the sampling unit 120 in FIG. 1A ) and the amplification unit (for example: the amplification unit 140 in FIG. 1A ) is the same as that of the embodiment shown in FIG. 1A , so the related description will not be repeated.

To sum up, the comparator invented by the present invention can have multiple applications, and can effectively improve the operation reliability through various voltage setting methods under process variation.

Although the content of the present invention has been disclosed above in terms of implementation, it is not intended to limit the present invention. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the content of the present invention. Therefore, the scope of protection of the present invention should be defined by the scope of protection of the appended claims.

Claims (10)

1. An electronic device, characterized in that it comprises: a sampling unit, used to selectively sample a first input signal and a second input signal, and generate a difference signal; and An amplifying unit for receiving the difference signal and generating an output signal, wherein the amplifying unit is controlled by a first preset voltage, a second preset voltage, a first system supply voltage and a second system supply voltage drive, Wherein the first preset voltage is used to set an operating point of the amplifying unit, and the second preset voltage is greater than the first system supply voltage. 2. The electronic device according to claim 1, wherein the amplifying unit comprises a switch having a threshold voltage, and in normal operation, the first preset voltage is a first voltage, and the second preset voltage is The voltage is a second voltage greater than the sum of the first system supply voltage and the threshold voltage, and when the switch changes, the first preset voltage is set as an offset value between the first voltage and the threshold voltage sum, and the second preset voltage is set as the sum of the second voltage and the offset value. 3. The electronic device according to claim 1, wherein the sampling unit comprises: a capacitor for generating the difference signal; a first switch, used for selectively conducting according to a first control signal, so as to transmit the first input signal to the capacitor; and A second switch is used for selectively conducting according to a second control signal to transmit the second input signal to the capacitor, wherein the first control signal and the second control signal are opposite phases. 4. The electronic device according to claim 3, wherein the amplifying unit comprises: A third switch is used for selectively conducting according to the first control signal to transmit the first preset voltage to the capacitor so as to adjust the level of the difference signal. 5. The electronic device according to claim 4, wherein the amplifying unit is further driven by a third preset voltage, the third preset voltage is greater than or equal to the second system supply voltage, and the amplifying unit further comprises A plurality of switches, each of the switches includes a first terminal, a second terminal and a control terminal, and the switches include: a fourth switch, wherein the first terminal of the fourth switch is used to receive the first system supply voltage, and the control terminal of the fourth switch is used to receive the second preset voltage; A fifth switch, wherein the first terminal of the fifth switch is electrically coupled to the second terminal of the fourth switch, the second terminal of the fifth switch is used to receive the second system supply voltage, and the The control end of the fifth switch is used to receive the difference signal; A sixth switch, wherein the first terminal of the sixth switch is used to receive the second preset voltage or the first system supply voltage, and the control terminal of the sixth switch is used to receive the second preset voltage ; A seventh switch, wherein the first terminal of the seventh switch is electrically coupled to the second terminal of the sixth switch, the second terminal of the seventh switch is used to receive the third preset voltage, and the The control end of the seventh switch is electrically coupled to the second end of the fourth switch; An eighth switch, wherein the first terminal of the eighth switch is used to receive the first system supply voltage, the second terminal of the eighth switch is used to output the output signal, and the control terminal of the eighth switch electrically coupled to the second end of the sixth switch; and A ninth switch, wherein the first terminal of the ninth switch is electrically coupled to the second terminal of the eighth switch, the second terminal of the ninth switch is used to receive the third preset voltage, and the The control end of the ninth switch is electrically coupled to the second end of the fourth switch. 6. The electronic device according to claim 5, wherein the third preset voltage is a first voltage during normal operation, and when the switches change, the first preset voltage is set to the The sum of the first voltage and an offset value of a threshold voltage of the switches, the second preset voltage is set as the sum of the second voltage and the offset value, and the third preset voltage is set as the first voltage The difference between a voltage and the offset value. 7. The electronic device according to claim 4, wherein the amplifying unit further comprises: A fourth switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the fourth switch is used to receive the first system supply voltage, and the second terminal of the fourth switch is used for to generate the output signal, and the control terminal of the fourth switch is used to receive the second preset voltage; and A fifth switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the fifth switch is electrically coupled to the second terminal of the fourth switch, the fifth switch of the fifth switch The first end is used for receiving the second system supply voltage, and the control end of the fifth switch is used for receiving the difference signal. 8. A comparator having an output terminal for outputting an output signal, characterized in that the comparator comprises: A first switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the first switch is used to receive a first input signal, and the control terminal of the first switch is used to receiving a first control signal; A second switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the second switch is used to receive a second input signal, and the control terminal of the second switch is used to receiving a second control signal, wherein the first control signal and the second control signal are opposite phases; a capacitor, wherein a first end of the capacitor is electrically coupled to the second end of the first switch and the second end of the second switch; A third switch includes a first terminal, a second terminal and a control terminal, wherein the first terminal of the third switch is electrically coupled to a second terminal of the capacitor, and the second terminal of the third switch The terminal is used to receive a first preset voltage, and the control terminal of the third switch is used to receive the first control signal; A fourth switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the fourth switch is used to receive a first system supply voltage, and the second terminal of the fourth switch is is coupled to the output terminal of the comparator, and the control terminal of the fourth switch is used to receive a second preset voltage; and A fifth switch, including a first end, a second end and a control end, wherein the first end of the fifth switch is electrically coupled to the second end of the capacitor, the first end of the fifth switch The two terminals are used to receive a second system supply voltage, and the control terminal of the fifth switch is electrically coupled to the second terminal of the capacitor. 9. The comparator of claim 8, further comprising: A sixth switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the sixth switch is used to receive the second preset voltage or the first system supply voltage, and the first terminal The control end of the six switches is used to receive the second preset voltage; A seventh switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the seventh switch is electrically coupled to the second terminal of the sixth switch, the seventh switch of the The second terminal is used to receive a third preset voltage, and the control terminal of the seventh switch is electrically coupled to the second terminal of the fourth switch; An eighth switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the eighth switch is used to receive the first system default voltage, and the second terminal of the eighth switch electrically coupled to the output terminal, and the control terminal of the eighth switch is electrically coupled to the second terminal of the sixth switch; and A ninth switch, including a first terminal, a second terminal and a control terminal, wherein the first terminal of the ninth switch is electrically coupled to the second terminal of the eighth switch, and the ninth switch of the ninth switch The second end is used to receive the third preset voltage, and the control end of the ninth switch is electrically coupled to the second end of the fourth switch. 10. The comparator as claimed in claim 9, wherein during normal operation, the first preset voltage is a first voltage, and the second preset voltage is greater than the first system supply voltage and the A second voltage of the sum of a threshold voltage of the switches, the third preset voltage is a third voltage greater than or equal to the second system supply voltage, when the switches vary, the first preset voltage is set to The sum of the first voltage and an offset value of the threshold voltage, the second preset voltage is set as the sum of the second voltage and the offset value, and the third preset voltage is set as the third voltage and the offset value The difference between this offset value.