Signal conversion device and circuit system using same

Abstract

The invention discloses a signal conversion device and a circuit system using the same, and the signal conversion device is used for converting a single-ended input voltage into a differential input voltage with a positive input voltage and a negative input voltage, and is specifically used for a sampling stage, a holding stage and a common-mode voltage generation stage, electrically connecting one capacitor associated with a positive input voltage to a single-ended input voltage, and electrically connecting one capacitor associated with a negative input voltage to a predetermined voltage; and in a single-ended to differential phase, electrically connecting the capacitor associated with the positive input voltage to a predetermined voltage, and electrically connecting the capacitor associated with the negative input voltage to a single-ended input voltage. Therefore, the common-mode voltage is irrelevant to the capacitance value ratio, and the capacitor does not need to be designed into a switching capacitor with a plurality of switches, so that complex control is not needed, and the parasitic effect of the circuit can be reduced.

Description

Technical Field

[0001] The present invention relates to a signal conversion device for converting a single-ended input voltage into a differential input voltage and a circuit system using the same, and in particular to a signal conversion device whose common mode voltage is independent of the capacitance ratio and is equal to half of the system voltage and a circuit system using the same. Background Art

[0002] Please refer to Figure 1 , Figure 1 1 is a circuit diagram of a signal conversion device of the prior art. The signal conversion device of the prior art includes a plurality of switches SW1, SW2, an operational amplifier CMP, a plurality of capacitors CA, CB and a control logic circuit 11. One of the plurality of switches SW2 is switched to electrically connect the capacitor CA to the single-ended input voltage VIN or the ground voltage GND, and another of the plurality of switches SW2 is switched to electrically connect the capacitor CA to the single-ended input voltage VIN or the system voltage AVDD, and the switch SW1 is switched to electrically connect the connection point between the capacitor CB and CA to the ground voltage, whereby the signal conversion device of the prior art generates a differential input voltage having a positive input voltage VCP and a negative input voltage VCN.

[0003] After the single-ended input voltage VIN is converted into a differential input voltage by using the signal conversion device of the prior art, the common-mode voltage of the differential input voltage is one-Nth of the single-ended input voltage VIN (i.e., VIN / N), and the differential input voltage is two-Nth of the single-ended input voltage VIN minus one-Nth of the system voltage AVDD (i.e., 2VIN / N-AVDD / N), where 1 / N is the capacitance ratio between the capacitance value of capacitor CA and the total capacitance value of capacitors CA and CB (i.e., 1 / N=CA / (CA+CB)). Obviously, the common-mode voltage is related to 1 / N, and 1 / N must be adjusted for different system voltages AVDD, so capacitors CA and CB are designed as switching capacitors and have multiple switches. The switches of the switching capacitors are switched by the control logic circuit 11 to select a suitable 1 / N. In short, the prior art requires complex logic control, and the design of the switching capacitor will cause the parasitic effect of the line to affect the performance of the overall signal conversion device. Summary of the invention

[0004] It can be understood from the above description that the present invention aims to solve the technical problems in the prior art that the common mode voltage is related to the ratio of the capacitance value and the capacitor needs to be designed as a switching capacitor, which requires complex logic control and generates parasitic line effects.

[0005] In order to solve the above-mentioned conventional problems, an embodiment of the present invention provides a signal conversion device, which is used to convert a single-ended input voltage into a differential input voltage having a positive input voltage and a negative input voltage, and includes a first voltage selector, a second voltage selector, a third voltage selector, a system voltage equalizer, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor. The first voltage selector is used to select a single-ended input voltage or a predetermined voltage as a first voltage output at its first end. The second voltage selector is used to select a single-ended input voltage or a predetermined voltage as a second voltage output at its second end, wherein the first voltage is different from the second voltage. The third voltage selector is used to select a system voltage or a ground voltage as a third voltage output at its third end. The system voltage equalizer has a fourth end and a fifth end, and is used to selectively connect the fourth end and the fifth end to the system voltage. The first capacitor is electrically connected between the first end and the fourth end. The second capacitor is electrically connected between the third end and the fourth end. The third capacitor is electrically connected between the ground voltage and the fourth end. The fourth capacitor is electrically connected between the second end and the fifth end. The fifth capacitor is electrically connected between the third end and the fifth end. The sixth capacitor is electrically connected between the ground voltage and the fifth terminal. The fourth terminal and the fifth terminal are respectively used to output a positive input voltage and a negative input voltage in the single-ended to differential stage.

[0006] In order to solve the above conventional problems and achieve the above technical effects, an embodiment of the present invention provides a circuit system, which includes the above signal conversion device and a functional circuit. The functional circuit is electrically connected to the signal conversion device and receives a differential input voltage to perform a specific function accordingly.

[0007] In summary, through the signal conversion device and the circuit system using the same provided by the embodiments of the present invention, the common mode voltage of the differential input voltage converted by the signal conversion device can be independent of the capacitance ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to make the above and other objects, features, advantages and embodiments of the present invention more clearly understood, the accompanying drawings are described as follows:

[0009] Figure 1 is a circuit diagram of a signal conversion device of the prior art;

[0010] Figure 2 is a circuit diagram of a signal conversion device according to an embodiment of the present invention;

[0011] Figure 3 is a waveform diagram of each switching signal of the signal conversion device according to an embodiment of the present invention;

[0012] Figure 4 and Figure 5 is an equivalent circuit diagram of the upper and lower halves of the signal conversion device of an embodiment of the present invention in the sampling stage;

[0013] Figure 6 and Figure 7 is an equivalent circuit diagram of the upper half and the lower half of the signal conversion device of an embodiment of the present invention in the holding stage;

[0014] Figure 8 and Fig. 9 is an equivalent circuit diagram of the upper half and the lower half of the signal conversion device of an embodiment of the present invention in the common mode voltage generation stage; and

[0015] Fig.10 and Fig.11 It is an equivalent circuit diagram of the upper half and the lower half of the signal conversion device of an embodiment of the present invention in the single-ended to differential stage. DETAILED DESCRIPTION

[0016] In order to solve the technical problems of the existing prior art, the embodiment of the present invention mainly provides a signal conversion device, which is used to convert a single-ended input voltage into a differential input voltage having a positive input voltage and a negative input voltage, and is specifically used to: in the sampling stage, the holding stage and the common-mode voltage generation stage, make a capacitor associated with the positive input voltage electrically connected to the single-ended input voltage, and make a capacitor associated with the negative input voltage electrically connected to a predetermined voltage; and in the single-ended to differential stage, make the capacitor associated with the positive input voltage electrically connected to a predetermined voltage, and make the capacitor associated with the negative input voltage electrically connected to the single-ended input voltage. In this way, the common-mode voltage will be independent of the capacitance value ratio, and the capacitor does not need to be designed as a switching capacitor with multiple switches, so there is no need for complex control, and the line parasitic effect can be reduced.

[0017] On the other hand, the present invention further provides a circuit system, which includes the above-mentioned signal conversion device and a functional circuit. The functional circuit is electrically connected to the signal conversion device to receive a differential input voltage and perform a specific function accordingly. For example, the functional circuit can be a processing circuit of a sound output device, a front-end circuit of a wireless communication device, or a signal enhancement circuit of an instrument device, and the present invention is not limited thereto.

[0018] Please refer to Figure 2 , Figure 2 is a circuit diagram of a signal conversion device according to an embodiment of the present invention. Figure 2The signal conversion device is used to convert a single-ended input voltage VIN into a differential input voltage having a positive input voltage VCP and a negative input voltage VCN, and includes a plurality of voltage selectors, a system voltage equalizer, and a plurality of capacitors CA-CC, wherein switches SW4 and SW5 in the upper half constitute one of the voltage selectors, switches SW4 and SW5 in the lower half constitute another voltage selector, switches SW2 and SW3 constitute another voltage selector, and two switches SW1 constitute a system voltage equalizer. It is noted that the signal conversion device may further include an operational amplifier CMP, but the operational amplifier CMP is not a necessary component of the signal conversion device.

[0019] The voltage selector composed of the switches SW4 and SW5 in the upper part is used to select the single-ended input voltage VIN or the predetermined voltage VCM_HV as the selected voltage output at one end connected to the capacitor CA in the upper part. The voltage selector composed of the switches SW4 and SW5 in the lower part is used to select the single-ended input voltage VIN or the predetermined voltage VCM_HV as the selected voltage output at one end connected to the capacitor CA in the lower part. The voltage selector composed of the switches SW2 and SW3 is used to select the system voltage VDD_L (Note: In this embodiment, the low-voltage system voltage VDD_L is used as an example, but the present invention is not limited to this) or the ground voltage GND as the selected voltage output at one end connected to the two capacitors CB. Further, the input end of the switch SW2 and the input end of the switch SW3 are electrically connected to the system voltage VDD_L and the ground voltage GND, respectively, and the switches SW2 and SW3 are respectively controlled by the second switching signal and the third switching signal to be closed or opened.

[0020] The input ends of the switches SW4 and SW5 in the upper part are electrically connected to the single-ended input voltage VIN and the predetermined voltage VCM_HV, respectively, and the input ends of the switches SW4 and SW5 in the lower part are electrically connected to the predetermined voltage VCM_HV and the single-ended input voltage VIN, respectively, so the selected voltage received by one end of the capacitor CA in the upper part is different from the selected voltage received by one end of the capacitor CA in the lower part. Further, the switches SW4 and SW5 are respectively controlled by the fourth switching signal and the fifth switching signal to be closed or opened, and when the voltage selector formed by the switches SW4 and SW5 in the upper part selects the predetermined voltage VCM_HV, the voltage selector formed by the switches SW4 and SW5 in the lower part selects the single-ended input voltage VIN, and vice versa.

[0021] The system voltage equalizer composed of two switches SW1 is used to selectively connect the two ends connected to the positive input terminal and the negative input terminal of the operational amplifier CMP to the system voltage VDD_L, wherein the output end of the upper switch SW1 and the output end of the lower switch SW1 are respectively electrically connected to the positive input terminal and the negative input terminal of the operational amplifier CMP, the input ends of the two switches SW1 are electrically connected to the system voltage VDD_L, and the two switches SW1 are controlled by the first switching signal to be closed or opened. In short, through the control of the first switching signal, the voltages on the positive input terminal and the negative input terminal of the operational amplifier CMP will be selectively equalized to the system voltage VDD_L.

[0022] The capacitor CA of the upper half is electrically connected between one end of the voltage selector formed by the switches SW4 and SW5 of the upper half and one end of the system voltage equalizer. Further, one end of the capacitor CA of the upper half is electrically connected to the output end of the switches SW4 and SW5 of the upper half, and the other end of the capacitor CA of the upper half is electrically connected to the output end of the switch SW1 of the upper half. The capacitor CB of the upper half is electrically connected between one end of the voltage selector formed by the switches SW2 and SW3 and one end of the system voltage equalizer. Further, one end of the capacitor CB of the upper half is electrically connected to the output end of the switches SW2 and SW3, and the other end of the capacitor CB of the upper half is electrically connected to the output end of the switch SW1 of the upper half. The capacitor CC of the upper half is electrically connected between the ground voltage GND and one end of the system voltage equalizer. Further, one end of the capacitor CC of the upper half is electrically connected to the ground voltage GND, and the other end of the capacitor CC of the upper half is electrically connected to the output end of the switch SW1 of the upper half.

[0023] The capacitor CA of the lower half is electrically connected between one end of the voltage selector formed by the switches SW4 and SW5 of the lower half and the other end of the system voltage equalizer. Further, one end of the capacitor CA of the lower half is electrically connected to the output end of the switches SW4 and SW5 of the lower half, and the other end of the capacitor CA of the lower half is electrically connected to the output end of the switch SW1 of the lower half. The capacitor CB of the lower half is electrically connected between one end of the voltage selector formed by the switches SW2 and SW3 and the other end of the system voltage equalizer. Further, one end of the capacitor CB of the lower half is electrically connected to the output end of the switches SW2 and SW3, and the other end of the capacitor CB of the lower half is electrically connected to the output end of the switch SW1 of the lower half. The capacitor CC of the lower half is electrically connected between the ground voltage GND and the other end of the system voltage equalizer. Further, one end of the capacitor CC of the lower half is electrically connected to the ground voltage GND, and the other end of the capacitor CC of the lower half is electrically connected to the output end of the switch SW1 of the lower half.

[0024] In this embodiment, the capacitance value of the upper capacitor CA is the same as that of the lower capacitor CA, the capacitance value of the upper capacitor CB is the same as that of the lower capacitor CB, and the capacitance value of the upper capacitor CC is the same as that of the lower capacitor CC. Through the signal conversion device of the present invention, the positive input voltage VCP is half of the system voltage VDD_L plus one-Nth of the predetermined voltage minus one-Nth of the single-ended input voltage (i.e., VCP=VDD_L / 2+VCM_HV / N-VIN / N), the negative input voltage VCN is half of the system voltage VDD_L plus one-Nth of the single-ended input voltage minus one-Nth of the predetermined voltage (i.e., VCN=VDD_L / 2-VCM_HV / N+VIN / N), and 1 / N is the capacitance value ratio of the capacitance value of the capacitor CA to the total capacitance value of the capacitors CA, CB, and CC (i.e., 1 / N=CA / (CA+CB+CC)).

[0025] From the above content, it can be known that the common mode voltage of the positive input voltage VCP and the negative input voltage VCN is half of the system voltage (i.e., VDD_L / 2), which is independent of the capacitance value ratio, so there is no need to design the capacitors CA, CB, and CC as switching capacitors, which reduces the complex logic control, the number of switches, and the parasitic effects of the circuit. In addition, the differential input voltage is two-N of the predetermined voltage VCM_HV minus two-N of the single-ended input voltage VIN (i.e., 2*(VCM_HV / N-VIN / N)). If the predetermined voltage VCM_HV is selected as half of the system voltage VDD_L (i.e., VCM_HV=VDD_L / 2), the differential input voltage is one-N of the system voltage VDD_L minus two-N of the single-ended input voltage VIN (i.e., VDDL / N-2*VIN / N), so the swing range of the differential input voltage can be increased.

[0026] Please refer to Figure 2 , Figure 3 , Figure 4 and Figure 5 In the sampling phase P1, switches SW1, SW2, and SW4 are turned on, while switches SW3 and SW5 are turned off. The voltage selector formed by the upper switches SW4 and SW5 selects the single-ended input voltage VIN, the voltage selector formed by the lower switches SW4 and SW5 selects the predetermined voltage VCM_HV, the voltage selector formed by switches SW2 and SW3 selects the system voltage VDD_L, and the system voltage equalizer equalizes one end of the positive input voltage VCP and one end of the negative input voltage VCN to the system voltage VDD_L. In this way, Figure 4 As shown, the voltage difference across the upper capacitor CA is VCA=VDD_L-VIN, the voltage difference across the upper capacitor CB is VCB=0, and the voltage difference across the upper capacitor CC is VCC=VDD_L; and, as Figure 5 As shown, the voltage difference across the lower capacitor CA is VCA=VDD_L-VCM_HV, the voltage difference across the lower capacitor CB is VCB=0, and the voltage difference across the lower capacitor CC is VCC=VDD_L.

[0027] Please refer to Figure 2 , Figure 3 , Figure 6 and Figure 7 In the holding phase P2, switches SW2 and SW4 are turned on, while switches SW1, SW3, and SW5 are turned off. The voltage selector formed by the upper switches SW4 and SW5 selects the single-ended input voltage VIN, the voltage selector formed by the lower switches SW4 and SW5 selects the predetermined voltage VCM_HV, the voltage selector formed by switches SW2 and SW3 selects the system voltage VDD_L, and the system voltage equalizer no longer equalizes one end of the positive input voltage VCP and one end of the negative input voltage VCN to the system voltage VDD_L. In this way, Figure 6 As shown, the voltage difference across the upper capacitor CA is VCA=VDD_L-VIN, the voltage difference across the upper capacitor CB is VCB=0, and the voltage difference across the upper capacitor CC is VCC=VDD_L; and, as Figure 7 As shown, the voltage difference across the lower capacitor CA is VCA=VDD_L-VCM_HV, the voltage difference across the lower capacitor CB is VCB=0, and the voltage difference across the lower capacitor CC is VCC=VDD_L.

[0028] Please refer to Figure 2 , Figure 3 , Figure 8 and Fig. 9 In the sub-stage P3-1 of the common-mode voltage generation stage P3, only the switch SW4 is turned on, and then in the sub-stage P3-2 of the common-mode voltage generation stage P3, only the switches SW3 and SW4 are turned on. Therefore, in the sub-stage P3-2 of the common-mode voltage generation stage P3, the voltage selector composed of the upper half switches SW4 and SW5 selects the single-ended input voltage VIN, the voltage selector composed of the lower half switches SW4 and SW5 selects the predetermined voltage VCM_HV, the voltage selector composed of the switches SW2 and SW3 selects the ground voltage GND, and the system voltage equalizer no longer equalizes one end of the positive input voltage VCP and one end of the negative input voltage VCN to the system voltage VDD_L. In this way, Figure 8 As shown, the voltage difference across the upper capacitor CA is VCA=VDD_L / 2-VIN, the voltage difference across the upper capacitor CB is VCB=VDD_L / 2, and the voltage difference across the upper capacitor CC is VCB=VDD_L / 2; and, as Fig. 9 As shown, the voltage difference across the lower capacitor CA is VCA=VDD_L / 2-VCM_HV, the voltage difference across the lower capacitor CB is VCB=VDD_L / 2, and the voltage difference across the lower capacitor CC is VCC=VDD_L / 2.

[0029] Please refer to Figure 2 , Figure 3 , Fig.10 and Fig.11 In the sub-stage P4-1 of the single-ended to differential stage P4, only the switch SW3 is turned on, and then in the sub-stage P4-2 of the single-ended to differential stage P4, only the switches SW3 and SW5 are turned on. Therefore, in the sub-stage P4-2 of the single-ended to differential stage P4, the voltage selector composed of the upper half switches SW4 and SW5 selects the predetermined voltage VCM_HV, the voltage selector composed of the lower half switches SW4 and SW5 selects the single-ended input voltage VIN, the voltage selector composed of the switches SW2 and SW3 selects the ground voltage GND, and the system voltage equalizer no longer equalizes one end of the positive input voltage VCP and one end of the negative input voltage VCN to the system voltage VDD_L. In this way, Fig.10 As shown, the positive input voltage VCP = VDD_L / 2-(VIN-VCM_HV) / N, the voltage difference across the upper capacitor CA is VCA = VDD_L / 2-(VIN-VCM_HV) / N-VCM_HV, the voltage difference across the upper capacitor CB is VCB = VDD_L / 2-(VIN-VCM_HV) / N, and the voltage difference across the upper capacitor CC is VCB = VDD_L / 2-(VIN-VCM_HV) / N; and, as Fig.11 As shown, the negative input voltage VCN = VDD_L / 2-(VCM_HV-VIN) / N, the voltage difference across the capacitor CA in the lower half is VCA = VDD_L / 2-(VCM_HV-VIN) / N-VIN, the voltage difference across the capacitor CB in the lower half is VCB = VDD_L / 2-(VCM_HV-VIN) / N, and the voltage difference across the capacitor CC in the lower half is VCC = VDD_L / 2-(VCM_HV-VIN) / N.

[0030] Accordingly, the signal conversion device and circuit system provided by the embodiment of the present invention achieves the technical effect that the common mode voltage is independent of the capacitance value ratio, so there is no need to design the capacitor as a switching capacitor, thereby reducing complex logic control, the number of switches and line parasitic effects. Furthermore, the introduced predetermined voltage can be selected to be half of the system voltage to increase the swing range of the differential input voltage.

[0031] The present invention is disclosed herein only in terms of preferred embodiments. However, anyone familiar with the technical field should understand that the above embodiments are only used to describe the present invention and are not used to limit the scope of the claims claimed by the present invention. Any changes or substitutions that are equal or equivalent to the above embodiments should be interpreted as being included in the spirit or scope of the present invention. Therefore, the protection scope of the present invention should be based on the definition of the claims.

Claims

1. A signal conversion device for converting a single-ended input voltage into a differential input voltage having a positive input voltage and a negative input voltage, characterized in that: include: A first voltage selector, used for selecting the single-ended input voltage or a predetermined voltage as a first voltage to be outputted at a first end thereof; A second voltage selector, used for selecting the single-ended input voltage or the predetermined voltage as a second voltage to be outputted at a second end thereof, wherein the first voltage is different from the second voltage; A third voltage selector, used for selecting a system voltage or a ground voltage as a third voltage to be outputted at a third terminal; A system voltage equalizer having a fourth terminal and a fifth terminal, for selectively connecting the fourth terminal and the fifth terminal electrically to the system voltage; A first capacitor, electrically connected between the first end and the fourth end; A second capacitor, electrically connected between the third end and the fourth end; A third capacitor, electrically connected between the ground voltage and the fourth end; a fourth capacitor, electrically connected between the second end and the fifth end; a fifth capacitor, electrically connected between the third terminal and the fifth terminal; as well as A sixth capacitor electrically connected between the ground voltage and the fifth terminal The fourth terminal and the fifth terminal are respectively used to output the positive input voltage and the negative input voltage in the single-ended to differential stage.

2. The signal conversion device according to claim 1, characterized in that: The system voltage equalizer includes two first switches, wherein the input end and the output end of one of the two first switches are electrically connected to the system voltage and the fourth end respectively, and the input end and the output end of the other of the two first switches are electrically connected to the system voltage and the fifth end respectively, and the two first switches are controlled by a first switching signal to selectively connect the fourth end and the fifth end to the system voltage.

3. The signal conversion device according to claim 1, characterized in that: The third voltage selector includes a second switch and a third switch, the input end and the output end of the second switch are electrically connected to the system voltage and the third end respectively, the input end and the output end of the third switch are electrically connected to the ground voltage and the third end respectively, the second switch is controlled by a second switching signal to selectively connect the third end to the system voltage, and the third switch is controlled by a third switching signal to selectively connect the third end to the ground voltage.

4. The signal conversion device according to claim 1, characterized in that: Each of the first voltage selector and the second voltage selector includes a fourth switch and a fifth switch, the input end and the output end of the fourth switch of the first voltage selector are electrically connected to the single-ended input voltage and the first end, respectively, the input end and the output end of the fifth switch of the first voltage selector are electrically connected to the predetermined voltage and the first end, respectively, the input end and the output end of the fourth switch of the second voltage selector are electrically connected to the predetermined voltage and the second end, respectively, the input end and the output end of the fifth switch of the second voltage selector are electrically connected to the single-ended input voltage and the first end, respectively, the fourth switch of the first voltage selector and the fourth switch of the second voltage selector are controlled by a fourth switching signal to selectively electrically connect the first end and the second end to the single-ended input voltage and the predetermined voltage, and the fifth switch of the first voltage selector and the fifth switch of the second voltage selector are controlled by a fifth switching signal to selectively electrically connect the first end and the second end to the predetermined voltage and the single-ended input voltage, respectively.

5. The signal conversion device according to claim 1, characterized in that: The capacitance value of the first capacitor is the same as the capacitance value of the fourth capacitor, the capacitance value of the second capacitor is the same as the capacitance value of the fifth capacitor, and the capacitance value of the third capacitor is the same as the capacitance value of the sixth capacitor.

6. The signal conversion device according to claim 1, characterized in that: The common mode voltage of the positive input voltage and the negative input voltage is half of the system voltage.

7. The signal conversion device according to claim 5, characterized in that: In the single-ended to differential stage, the positive input voltage is half of the system voltage plus one-Nth of the predetermined voltage minus one-Nth of the single-ended input voltage, and the negative input voltage is half of the system voltage plus one-Nth of the single-ended input voltage minus one-Nth of the predetermined voltage, where 1 / N is the capacitance value ratio of the capacitance value of the first capacitor to a total capacitance value of the first capacitor, the second capacitor and the third capacitor.

8. The signal conversion device according to claim 7, characterized in that: The predetermined voltage is half of the system voltage, and the differential input voltage is one-Nth of the system voltage minus two-Nth of the single-ended input voltage.

9. The signal conversion device according to claim 1, characterized in that: In the sampling stage, the system voltage equalizer electrically connects the fourth terminal and the fifth terminal to the system voltage, the third voltage selector selects and outputs the system voltage as the third voltage, the first voltage selector selects and outputs the single-ended input voltage as the first voltage, and the second voltage selector selects and outputs the predetermined voltage as the second voltage; In the holding stage, the system voltage equalizer does not electrically connect the fourth end and the fifth end to the system voltage, the third voltage selector selects and outputs the system voltage as the third voltage, the first voltage selector selects and outputs the single-ended input voltage as the first voltage, and the second voltage selector selects and outputs the predetermined voltage as the second voltage; in the common-mode voltage generation stage, the system voltage equalizer does not electrically connect the fourth end and the fifth end to the system voltage, the third voltage selector selects and outputs the ground voltage as the third voltage, the first voltage selector selects and outputs the single-ended input voltage as the first voltage, and the second voltage selector selects and outputs the predetermined voltage as the second voltage; and in the single-ended to differential stage, the system voltage equalizer does not electrically connect the fourth end and the fifth end to the system voltage, the third voltage selector selects and outputs the ground voltage as the third voltage, the first voltage selector selects and outputs the predetermined voltage as the first voltage, and the second voltage selector selects and outputs the single-ended input voltage as the second voltage.

10. A circuit system, characterized in that: include: The signal conversion device according to any one of claims 1 to 9; The functional circuit is electrically connected to the signal conversion device to receive the differential input voltage and execute a specific function accordingly.

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