Single-ended to differential circuit and electronic equipment

Abstract

A single-ended to differential circuit and an electronic device, the single-ended to differential circuit being adapted to convert a single-ended signal into a differential signal, the single-ended to differential circuit comprising: a first operational amplifier whose first input end inputs the single-ended signal, whose second input end is coupled to its output end, and whose output end is coupled to a second input end of a third operational amplifier; the first input end of the second operational amplifier inputs power supply noise interference, the second input end of the second operational amplifier is coupled with the second input end of the first operational amplifier, and the output end of the second operational amplifier is coupled with the first input end of the third operational amplifier; the first input end of the third operational amplifier also inputs ground end noise interference, and the output end of the third operational amplifier outputs a first signal; the output end of the reference voltage output unit outputs a second signal; the differential signal includes a first signal and a second signal. According to the scheme, a network formed by a plurality of operational amplifiers is adopted, and a single-ended signal is converted into a differential signal.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a single-ended to differential circuit and electronic equipment. Background Art

[0002] In the circuit field, a single-ended signal refers to the voltage or current of a signal relative to a reference potential, which is transmitted on a signal line and is easily affected by external noise and interference. A differential signal refers to the voltage difference or current difference between two signals. Compared with a single-ended signal, a differential signal has stronger anti-interference ability and higher signal integrity.

[0003] In the prior art, single-ended to differential conversion is usually implemented through a differential amplifier. The single-ended signal is converted into a differential signal through the differential amplifier. The differential amplifier is usually implemented through a transformer, a coupling capacitor or a differential driver.

[0004] Currently, the circuit for converting single-ended data to differential data is relatively complex. Summary of the invention

[0005] The present invention aims at providing a single-ended to differential converter circuit, which uses a network composed of a plurality of operational amplifiers to convert a single-ended signal into a differential signal.

[0006] In a first aspect, the present invention provides a single-ended to differential circuit, which is suitable for converting a single-ended signal into a differential signal; it comprises: a first operational amplifier, a second operational amplifier, a third operational amplifier and a reference voltage output unit, wherein: the first operational amplifier, its first input terminal inputs the single-ended signal, its second input terminal is coupled to its output terminal, and its output terminal is coupled to the second input terminal of the third operational amplifier; the second operational amplifier, its first input terminal inputs power supply noise interference, its second input terminal is coupled to the second input terminal of the first operational amplifier, and its output terminal is coupled to the first input terminal of the third operational amplifier; the third operational amplifier, its first input terminal also inputs ground noise interference, and its output terminal outputs a first signal; the reference voltage output unit, its output terminal outputs a second signal; the differential signal comprises the first signal and the second signal.

[0007] Optionally, the single-ended to differential circuit may also include: a first feedback resistor, a second feedback resistor and a third feedback resistor, wherein: the first feedback resistor is coupled between the second input terminal of the first operational amplifier and the output terminal of the first operational amplifier; the second feedback resistor is coupled between the second input terminal of the second operational amplifier and the output terminal of the second operational amplifier; the third feedback resistor is coupled between the second input terminal of the third operational amplifier and the output terminal of the second operational amplifier.

[0008] Optionally, the single-ended to differential circuit may further include: a first current limiting resistor coupled between the output terminal of the first operational amplifier and the second input terminal of the third operational amplifier.

[0009] Optionally, the single-ended to differential circuit may further include: a second current limiting resistor coupled between the output terminal of the second operational amplifier and the first input terminal of the third operational amplifier.

[0010] Optionally, the single-ended to differential circuit may further include: a third current limiting resistor, a first end of which is input with the ground noise interference, and a second end of which is coupled with the first input end of the third operational amplifier.

[0011] Optionally, the single-ended to differential circuit may further include: an adjustable resistor, a first end of which is coupled to the first input end of the first operational amplifier, and a second end of which is coupled to the second input end of the second operational amplifier.

[0012] Optionally, the amplitude of the second signal is smaller than the amplitude of the first signal.

[0013] Optionally, the single-ended to differential circuit may also include: a first capacitor and a first resistor, wherein: the first capacitor has a first end that inputs the single-ended signal and a second end that is coupled to the first end of the first resistor; the first resistor has a second end that is coupled to the first input end of the first operational amplifier.

[0014] In a second aspect, the present invention further provides an electronic device, comprising the single-ended to differential circuit provided by any one of the above embodiments.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The input single-ended signal is amplified by the operational amplifier network composed of the first operational amplifier, the second operational amplifier and the third operational amplifier to amplify the voltage difference between the input single-ended signal and the second signal output by the reference voltage output unit, thereby realizing the output of the differential signal. At the same time, since the operational amplifier network inputs power supply noise and ground noise, the operational amplifier network can filter out the common mode signal and obtain a differential signal with a high signal-to-noise ratio. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural schematic diagram of a single-ended to differential circuit in an embodiment of the present invention;

[0018] Figure 2 is a schematic structural diagram of another single-ended to differential circuit in an embodiment of the present invention;

[0019] Figure 3It is a structural schematic diagram of another single-ended to differential circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] As described in the background art, the method of converting a single-ended signal into a differential signal by using a differential amplifier or the like has a relatively complex circuit.

[0021] In the embodiment of the present invention, an operational amplifier network composed of a first operational amplifier, a second operational amplifier, and a third operational amplifier is used to amplify an input single-ended signal to amplify the voltage difference between the input single-ended signal and the second signal output by the reference voltage output unit, thereby realizing the output of a differential signal. At the same time, since the operational amplifier network inputs power supply noise and ground noise, the operational amplifier network can filter out common-mode signals and obtain a differential signal with a high signal-to-noise ratio. Moreover, the operational amplifier network composed of only operational amplifiers can realize the function of converting single-ended to differential, and has a simple structure and is relatively easy to realize.

[0022] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0023] The embodiment of the present invention provides a single-ended to differential conversion circuit, referring to Figure 1 .

[0024] In a specific implementation, the single-ended to differential circuit is suitable for converting an input single-ended signal into a differential signal. A single-ended signal may refer to a signal having a reference end and a signal end, which is usually transmitted using a data line, and the reference end is usually a ground end.

[0025] In an embodiment of the present invention, the single-ended to differential circuit may include a first operational amplifier A1, a second operational amplifier A2, a third operational amplifier A3 and a reference voltage output unit. The first operational amplifier A1, the second operational amplifier A2 and the third operational amplifier A3 may form an operational amplifier network.

[0026] In a specific implementation, the first input terminal of the first operational amplifier A1 can input the single-ended signal SIGNAL_IN, the second input terminal of the first operational amplifier A1 can be coupled to the output terminal of the first operational amplifier A1, and the output terminal of the first operational amplifier A1 is coupled to the second input terminal of the third operational amplifier A3;

[0027] a first input terminal of a second operational amplifier A2, wherein the second input terminal of the second operational amplifier A2 may be coupled to the second input terminal of the first operational amplifier A1, and an output terminal of the second operational amplifier A2 is coupled to the first input terminal of a third operational amplifier A3;

[0028] The first input terminal of the third operational amplifier A3 may also input ground noise interference, and the output terminal of the third operational amplifier A3 may output a first signal SIGNAL_OUT+;

[0029] The reference voltage output unit can output a reference voltage signal based on the power supply voltage, and the reference voltage signal is the second signal SIGNAL_OUT-; the above differential signal includes the first signal SIGNAL_OUT+ and the second signal SIGNAL_OUT-.

[0030] In a specific implementation, the power supply noise may be output by the digital-to-analog converter DAC0. The digital-to-analog converter DAC0 outputs the power supply noise in an analog signal format.

[0031] The above ground noise can be output by the digital-to-analog converter DAC1. The data converter DAC1 outputs the ground noise in an analog signal format.

[0032] In a specific implementation, the above-mentioned ground noise and power supply noise are the system interference of the electronic equipment, which can be obtained by direct crosstalk or coupling.

[0033] Alternatively, the power supply noise in the digital signal format may be measured in advance, and the power supply noise in the digital signal format may be input to the input end of DAC0 to obtain the power supply noise in the analog signal format; and the ground noise in the digital signal format may be measured in advance, and the ground noise in the digital signal format may be input to the input end of DAC1 to obtain the ground noise in the analog signal format.

[0034] In a specific implementation, the reference voltage output unit VREF may output the second signal SIGNAL_OUT-.

[0035] In some embodiments, the second signal SIGNAL_OUT- is the reference voltage output by the reference voltage output unit VREF. The output end of the reference voltage output unit can input the power supply voltage and output the second signal. Therefore, the second signal output by the reference voltage output unit actually also includes power supply noise.

[0036] In a specific implementation, the amplitude of the first signal may be greater than the amplitude of the second signal. Specifically, the second amplitude may be greater than the voltage of the ground terminal (0V) and be 1 / 2 of the amplitude of the first signal.

[0037] In some embodiments, the amplitude of the first signal is 5V, and the amplitude of the second signal is 2.5V.

[0038] Thus, the first operational amplifier A1, the second operational amplifier A2 and the third operational amplifier A3 form an operational amplifier network to output the first signal in the differential signal; the second signal in the differential signal is output through the reference voltage output unit, thereby realizing the conversion of the single-ended signal into a differential signal and outputting the differential signal.

[0039] In a specific implementation, the above-mentioned single-ended to differential circuit may further include a feedback resistor, a current limiting resistor, etc. Figure 2 , a schematic diagram of the structure of another single-ended to differential circuit in an embodiment of the present invention is given.

[0040] In a specific implementation, the single-ended to differential circuit may further include: a first feedback resistor R11, a second feedback resistor R12, and a third feedback resistor R13, wherein:

[0041] A first feedback resistor R11 is coupled between the output terminal of the first operational amplifier A1 and the second input terminal of the first operational amplifier A1;

[0042] A second feedback resistor R12 is coupled between the output terminal of the second operational amplifier A2 and the second input terminal of the second operational amplifier A2;

[0043] The third feedback resistor R13 is coupled between the output terminal of the third operational amplifier A3 and the second input terminal of the third operational amplifier A3.

[0044] In a specific implementation, the single-ended to differential circuit may further include a first current limiting resistor R21. A first end of the first current limiting resistor R21 is coupled to the output end of the first operational amplifier A1, and a second end of the first current limiting resistor R21 is coupled to the second input end of the third operational amplifier A3. In other words, the first current limiting resistor R21 is coupled between the output end of the first operational amplifier A1 and the second input end of the third operational amplifier A3.

[0045] The single-ended to differential circuit may further include a second current limiting resistor R22. A first end of the second current limiting resistor R22 is coupled to the output end of the second operational amplifier A2, and a second end of the second current limiting resistor R22 is coupled to the first input end of the third operational amplifier A3. In other words, the second current limiting resistor R22 is coupled between the output end of the second operational amplifier A2 and the first input end of the third operational amplifier A3.

[0046] The single-ended to differential circuit may further include a third current limiting resistor R23. A first end of the third current limiting resistor R23 is input with ground noise interference, and a second end of the third current limiting resistor R23 is coupled with a first input end of the third operational amplifier A3.

[0047] In a specific implementation, the single-ended to differential circuit may further include an adjustable resistor R0. A first end of the adjustable resistor R0 is coupled to a first input end of the first operational amplifier A1, and a second end of the adjustable resistor R0 is coupled to a second input end of the second operational amplifier A2.

[0048] Reference Figure 3 , a structural schematic diagram of another single-ended to differential circuit in an embodiment of the present invention is given.

[0049] In a specific implementation, the single-ended to differential circuit may further include a first capacitor C1 and a first resistor R31, wherein: the first end of the first capacitor C1 inputs a single-ended signal, the second end of the first capacitor C1 is coupled to the first end of the first resistor R31; the second end of the first resistor R31 is coupled to the first input end of the first operational amplifier A1.

[0050] By providing the first capacitor C1 , the DC component in the input single-ended signal can be isolated to avoid interference of the DC component on the obtained differential signal.

[0051] In a specific implementation, the first input terminal of the first operational amplifier A1 may be the non-inverting input terminal “+” of the first operational amplifier A1 , and the second input terminal of the first operational amplifier A1 may be the inverting input terminal “−” of the first operational amplifier A1 .

[0052] The first input terminal of the second operational amplifier A2 may be a non-inverting input terminal “+” of the second operational amplifier A2 , and the second input terminal of the second operational amplifier A2 may be an inverting input terminal “−” of the second operational amplifier A2 .

[0053] The first input terminal of the third operational amplifier A3 may be a non-inverting input terminal “+” of the third operational amplifier A3 , and the second input terminal of the third operational amplifier A3 may be an inverting input terminal “−” of the third operational amplifier A3 .

[0054] In summary, the operational amplifier network composed of the first operational amplifier, the second operational amplifier and the third operational amplifier amplifies the input single-ended signal to amplify the voltage difference between the input single-ended signal and the second signal output by the reference voltage output unit, thereby realizing the output of the differential signal. At the same time, since the operational amplifier network inputs power supply noise and ground noise, the operational amplifier network can filter out the common mode signal and obtain a differential signal with a high signal-to-noise ratio.

[0055] An embodiment of the present invention further provides an electronic device, comprising the single-ended to differential circuit provided by any of the above embodiments.

[0056] A person skilled in the art may understand that all or part of the steps in the various methods of the above embodiments may be completed by instructing the relevant hardware through a program, and the program may be stored in a computer-readable storage medium, which may include: ROM, RAM, disk or CD, etc.

[0057] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A single-ended to differential circuit, characterized in that: Suitable for converting a single-ended signal into a differential signal; comprising: a first operational amplifier, a second operational amplifier, a third operational amplifier and a reference voltage output unit, wherein: The first operational amplifier has a first input terminal inputting the single-ended signal, a second input terminal coupled to its output terminal, and an output terminal coupled to the second input terminal of the third operational amplifier; The second operational amplifier has a first input terminal inputting power supply noise interference, a second input terminal coupled to the second input terminal of the first operational amplifier, and an output terminal coupled to the first input terminal of the third operational amplifier; The third operational amplifier has a first input terminal that also inputs ground noise interference, and an output terminal that outputs a first signal; The reference voltage output unit has an output terminal that outputs a second signal; the differential signal includes the first signal and the second signal.

2. The single-ended to differential circuit according to claim 1, characterized in that: Also includes: A first feedback resistor, a second feedback resistor, and a third feedback resistor, wherein: The first feedback resistor is coupled between the second input terminal of the first operational amplifier and the output terminal of the first operational amplifier; The second feedback resistor is coupled between the second input terminal of the second operational amplifier and the output terminal of the second operational amplifier; The third feedback resistor is coupled between the second input terminal of the third operational amplifier and the output terminal of the second operational amplifier.

3. The single-ended to differential circuit according to claim 1, characterized in that: Also includes: The first current limiting resistor is coupled between the output terminal of the first operational amplifier and the second input terminal of the third operational amplifier.

4. The single-ended to differential circuit according to claim 1, wherein: Also includes: The second current limiting resistor is coupled between the output terminal of the second operational amplifier and the first input terminal of the third operational amplifier.

5. The single-ended to differential circuit according to claim 1, wherein: Also includes: A third current limiting resistor has a first end thereof inputting the ground noise interference, and a second end thereof coupled to the first input end of the third operational amplifier.

6. The single-ended to differential circuit according to claim 1, characterized in that: Also includes: An adjustable resistor has a first end coupled to the first input end of the first operational amplifier, and a second end coupled to the second input end of the second operational amplifier.

7. The single-ended to differential circuit according to claim 1, wherein: The amplitude of the second signal is smaller than the amplitude of the first signal.

8. The single-ended to differential circuit according to claim 1, characterized in that: Also includes: A first capacitor and a first resistor, wherein: The first capacitor has a first end inputting the single-ended signal, and a second end coupled to the first end of the first resistor; A second end of the first resistor is coupled to the first input end of the first operational amplifier.

9. An electronic device, characterized in that: It comprises the single-ended to differential circuit as claimed in any one of claims 1 to 8.

Images