High-precision absolute value voltage output method and circuit

Abstract

This invention discloses a high-precision absolute voltage output method and circuit, belonging to the field of integrated circuit technology. The circuit includes: a comparator module, a first switch module, an operational amplifier module, a V-I conversion module, a P-type current mirror module, an N-type current mirror module, an I-V conversion module, and a second switch module. This invention utilizes the comparator module to control the opening and closing of the switch to control the voltage output. The operational amplifier and current mirror are used to obtain the final output value according to the width-to-length ratio and resistance ratio of the MOSFET. This invention not only overcomes the nonlinear distortion and low accuracy problems of traditional diode absolute voltage circuits, but also overcomes the problems of large area and power consumption, and large errors near 0 values ​​in existing diodeless absolute voltage circuits. It has advantages such as high accuracy, small area, low power consumption, and ease of integration, and can be widely used in large-scale array readout circuits, audio processing, and other scenarios.

Description

Technical Field

[0001] This invention relates to a high-precision absolute voltage output method and circuit, belonging to the field of integrated circuit technology. Background Technology

[0002] An absolute value circuit outputs the absolute value of an input signal. When the input signal contains both positive and negative polarities, the absolute value circuit converts these signals into an output signal containing only positive amplitude. This circuit can be used in signal shaping, peak detection, and amplitude limiting. Common applications include readout circuits for large-scale arrays, audio processing, precision measurement, and control systems.

[0003] An absolute value rectifier is a high-precision rectifier, most commonly implemented using a diode-based circuit. By using a reverse-biased diode, the negative half of the input signal is isolated and reduced to zero at the trigger point, retaining the positive half to output an analog voltage signal. Connecting the rectifier diode in the feedback loop of an operational amplifier allows it to be turned on or off by even minute changes in the signal, thus achieving the effect of generating an absolute value.

[0004] The aforementioned absolute value circuit exhibits significant nonlinearity, which greatly affects its accuracy. Furthermore, in practical circuits, diodes have large size and power consumption, leading to higher area and power consumption for the absolute value circuit, which is detrimental to its use.

[0005] Patent CN113822086A proposes a novel diode-free absolute value circuit. This patent utilizes the inverting proportional-inverting function of an operational amplifier. During operation, a comparator determines the sign of the signal, and then the inverting proportional-inverting circuit module converts the negative signal into a positive value for output. Without considering operational amplifier offset and resistor offset, this circuit has high requirements for the operational amplifier, large area and power consumption, and large error near the 0 value. Summary of the Invention

[0006] To further improve the accuracy of absolute value circuits while reducing circuit area and power consumption, this invention provides a high-precision absolute value voltage output method and circuit, the technical solution of which is as follows:

[0007] The first objective of this invention is to provide a high-precision absolute value circuit, comprising: a comparator module, a first switch module, an operational amplifier module, a V1 / V1 conversion module, a P-type current mirror module, an N-type current mirror module, an IV1 / V1 conversion module, and a second switch module;

[0008] The comparator module is used to determine the sign of the input voltage signal and uses the determination result to control the conduction and cutoff of the first switch module and the second switch module.

[0009] The operational amplifier module is connected to the first switch module, and the VI conversion module is connected to the operational amplifier module. The operational amplifier module and the VI conversion module are used to convert negative voltage signals into current signals.

[0010] The P-type current mirror module and the N-type current mirror module are used to transmit the converted current signal; the IV conversion module is used to convert the current signal into a positive voltage signal and input it into the second switching module; the second switching module outputs the final voltage signal.

[0011] Optionally, the comparator module includes: a comparator;

[0012] The positive input terminal of the comparator is connected to the external input and the first switch module, the negative input terminal is grounded, and the output terminal is connected to the control terminals of the first switch module and the second switch module respectively.

[0013] Optionally, the first switch module includes: a first switch S1 and a second switch S2, one end of the first switch S1 is connected to an external input, and the other end is connected to the operational amplifier module; one end of the second switch S2 is connected to an external input, and the other end outputs the final voltage signal.

[0014] Optionally, the operational amplifier module includes an operational amplifier and an NMOS transistor NM1. The positive input terminal of the operational amplifier is connected to the first switch S1, the negative input terminal is connected to the VI conversion module and the source of the NMOS transistor NM1, and the output terminal is connected to the gate of the NMOS transistor NM1.

[0015] Optionally, the VI conversion module includes: a first resistor R1; one end of the first resistor R1 is connected to a first level voltage V1, and the other end is connected to the source of the NMOS transistor NM1.

[0016] Optionally, the IV conversion module includes: a second resistor R2; one end of the second resistor R2 is connected to the drain of NM3; the other end is connected to a second level voltage V2.

[0017] Optionally, the comparator is used to compare the input voltage signal and control the on and off of the first and second switching modules based on the comparison result;

[0018] When the input voltage Vin>0: the output of the comparator is 1, the second switch S2 is turned on, and the first switch S1 and the second switch module are turned off.

[0019] Input voltage Vin < 0: The comparator output is 0, the second switch S2 is turned off, and the first switch S1 and the second switch module are turned on.

[0020] Optionally, when the input voltage is negative, the output voltage of the circuit is:

[0021]

[0022] in, Input voltage; The converted voltage; , These are the voltage levels of the VI conversion module and the IV conversion module, respectively. , These are the width-to-length ratios of the two PMOS transistors in the P-type current mirror module. , These are the width-to-length ratios of the two NMOS transistors in the N-type current mirror module, respectively. and These are the resistance values ​​of the resistors in the VI conversion module and the IV conversion module, respectively.

[0023] Optionally, the circuit is implemented based on SMIC 55nm CMOS technology.

[0024] The second objective of this invention is to provide a high-precision absolute voltage output method, which utilizes the high-precision absolute circuit described in any of the above claims to achieve the output of the absolute voltage value.

[0025] The beneficial effects of this invention are:

[0026] This invention provides a high-precision absolute voltage output method and circuit, which uses a comparator module to control the opening and closing of a switch to control the voltage output. The switch in this invention uses a CMOS switch, and the final output value is obtained according to the width-to-length ratio and resistance ratio of the MOS transistor using an operational amplifier and a current mirror. This invention not only overcomes the problems of nonlinear distortion and low accuracy caused by traditional absolute voltage circuits that use diodes plus half-wave and full-wave rectification of operational amplifiers to output absolute voltage values, but also overcomes the problems of large area and power consumption and large error near 0 value in existing diodeless absolute voltage circuits.

[0027] Therefore, the CMOS absolute circuit of the present invention has high precision, small area, low power consumption, and is easy to integrate. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the absolute value circuit of the present invention.

[0030] Figure 2 The diagram shows the input and output voltage waveforms of the absolute value circuit of this invention.

[0031] Figure 3 This is a circuit error diagram for the absolute value circuit of the present invention.

[0032] Figure 4 This is the offset voltage diagram of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] Example 1:

[0035] This embodiment provides a high-precision absolute value circuit, including: a comparator module, a first switch module, an operational amplifier module, a VI conversion module, a P-type current mirror module, an N-type current mirror module, an IV conversion module, and a second switch module;

[0036] The comparator module is used to determine the sign of the input voltage signal and uses the result to control the on and off states of the first and second switching modules.

[0037] The operational amplifier module is connected to the first switch module, and the VI conversion module is connected to the operational amplifier module. The operational amplifier module and the VI conversion module are used to convert negative voltage signals into current signals.

[0038] The P-type and N-type current mirror modules are used to transmit the converted current signal; the IV conversion module converts the current signal into a positive voltage signal and inputs it to the second switching module; the second switching module outputs the final voltage signal.

[0039] Example 2:

[0040] This embodiment provides a high-precision absolute value circuit; see [link to documentation]. Figure 1 It includes: comparator module, operational amplifier module, VI converter module, P-type current mirror module, N-type current mirror module, IV converter module and switching module;

[0041] The comparator module includes: a comparator;

[0042] The operational amplifier module includes: an operational amplifier and an NMOS transistor NM1;

[0043] The VI conversion module includes: resistor R1;

[0044] The P-type current mirror module includes: PMOS transistor PM1 and PMOS transistor PM2;

[0045] The N-type current mirror module includes: NMOS transistor NM2 and NMOS transistor NM3;

[0046] The IV conversion module includes: resistor R2;

[0047] The switch module includes: switch S1, switch S2, and switch S3.

[0048] The comparator's positive input is connected to the external input, the input of switch S1, and the input of switch S2; its negative input is connected to ground; and its output is connected to the control terminals of switch S1, switch S2, and switch S3, respectively. The operational amplifier's positive input is connected to the output of switch S1; its negative input is connected to the source of NM1; and its output is connected to the gate of NM1. One end of the VI converter is connected to the voltage level V1, and the other end is connected to the source of NM1. The drain of the P-type current mirror PM1 is connected to the drain of NM1, and the drain of PM2 is connected to the drain of NM2. The drain of the N-type current mirror NM2 is connected to the drain of PM2, and the drain of NM3 is connected to one end of resistor R2. One end of the IV converter is connected to the drain of NM3, and the other end is connected to the voltage level V2.

[0049] The working principle of this embodiment is as follows: The signal is input to the positive input terminal of the comparator. The comparator determines whether the input voltage is positive or negative and outputs signals 0 and 1 to represent the determination result. The comparator output signal controls the switch in the switching module to be turned on or off. If the input voltage is positive, it is output directly; if the input signal is negative, the voltage is converted into a positive voltage through an operational amplifier, a VI conversion module, a P-type current mirror, an N-type current mirror, and an IV conversion module, and finally output through the switching module.

[0050] The high-precision absolute value circuit provided in this embodiment operates as follows:

[0051] (a) Signal comparison stage: Input voltage V IN The input is given to the positive input terminal of the comparator, and the negative input terminal is grounded. The output terminal of the comparator is connected to switches S1 and S2, where switches S1 and S2 control signals that are opposite, providing the input voltage as the output. Based on the comparator output result, two cases can be distinguished:

[0052] ①V in >0: The comparator output is 1, switch S1 is turned on and switch S2 is turned off;

[0053] ②V in <0: The comparator output is 0, switch S1 is off, and switch S2 is on.

[0054] (ii) VI conversion stage: When the input voltage is negative, VIN The voltage is transmitted from the positive input terminal of the operational amplifier to the VI conversion module via the negative input terminal, where it is converted into current. The conversion formula is as follows:

[0055]

[0056] in, Input voltage, To complete the current conversion, For VI conversion module level signals, This represents the resistance value.

[0057] (III) Current transmission stage: the generated current signal The current is transmitted through NM1, the P-type current mirror, and the N-type current mirror, and finally to the IV conversion module. The formula for the transmitted current is:

[0058]

[0059] in, For output current, The current is the result of the previous stage's conversion. , The aspect ratios of PM1 and PM2 are shown below. , These are the width-to-length ratios of NM2 and NM3, respectively.

[0060] (iv) IV-V conversion stage: current signal The IV converter module converts current into voltage, and the conversion formula is as follows:

[0061]

[0062] in, For the final output voltage, For the transmitted current signal, The voltage level for IV conversion. This represents the resistance value.

[0063] when , , , The circuit can realize the absolute value function, and the conversion formula is:

[0064]

[0065] (V) Output Detection Stage: Based on the comparator output, control the on / off state of switches S1, S2, and S3. When the input comparator voltage is positive, switch S2 is on, and switches S1 and S3 are off, directly outputting the positive input voltage. When the input comparator voltage is negative, switch S2 is off, and switches S1 and S3 are on. The negative value is converted into a positive value through the operational amplifier, VI conversion module, P-type current mirror, N-type current mirror, and IV conversion module, and then output through switch S3. This completes the CMOS absolute value circuit output process.

[0066] During the simulation phase, a ramp sampling signal was used to simulate and test the circuit. The ramp voltage signal ranged from -800mV to 800mV. The simulation results are attached. Figure 2 As shown, this invention converts a voltage range of -800mV to 0mV to 800mV to 0mV, while the original 0mV to 800mV is output normally, thus realizing the absolute value function.

[0067] The absolute value circuit error in this embodiment is shown in the appendix. Figure 3 As shown, under 45 PVT combinations with process angles tt, ff, ss, sf, fs, power supply voltage fluctuation range of -10%, 0, +10%, and temperature range of 0℃, 27℃, 80℃, the error can be within ±1mV within the voltage range of -400mV to 400mV.

[0068] The Monte Carlo simulation results for this embodiment are attached. Figure 4 As shown, simulations were performed using 2000 points, with an average error of 539uV. Under a confidence level of 99.7% (3σ), the offset voltage range was calculated to be ±4mV.

[0069] The absolute value circuit constructed in this embodiment is based on SMIC's 55nm CMOS process. However, the process simulation of this circuit is not limited to CMOS processes and is also applicable to other process environments. The circuit's power consumption is 100μW. This circuit can be applied to research in areas such as input voltage conversion of SAR ADCs, average value measurement instruments, and automatic control. Furthermore, this embodiment can operate normally at a low power supply voltage of 1.2V, meeting the requirements for low-voltage implementation.

[0070] Some steps in the embodiments of the present invention can be implemented using software, and the corresponding software program can be stored in a readable storage medium, such as an optical disc or a hard disk.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-precision absolute value circuit, characterized in that, The circuit includes: a comparator module, a first switch module, an operational amplifier module, a VI conversion module, a P-type current mirror module, an N-type current mirror module, an IV conversion module, and a second switch module; The comparator module is used to determine the sign of the input voltage signal and uses the determination result to control the conduction and cutoff of the first switch module and the second switch module. The operational amplifier module is connected to the first switch module, and the VI conversion module is connected to the operational amplifier module. The operational amplifier module and the VI conversion module are used to convert negative voltage signals into current signals. The P-type current mirror module and the N-type current mirror module are used to transmit the converted current signal; the IV conversion module is used to convert the current signal into a positive voltage signal and input it into the second switching module; the second switching module outputs the final voltage signal. The comparator module includes: a comparator; The positive input terminal of the comparator is connected to the external input and the first switch module, the negative input terminal is grounded, and the output terminal is connected to the control terminals of the first switch module and the second switch module respectively. The first switch module includes a first switch (S1) and a second switch (S2). One end of the first switch (S1) is connected to an external input, and the other end is connected to the operational amplifier module. One end of the second switch (S2) is connected to an external input, and the other end outputs the final voltage signal.

2. The high-precision absolute value circuit according to claim 1, characterized in that, The operational amplifier module includes an operational amplifier and an NMOS transistor (NM1). The positive input terminal of the operational amplifier is connected to the first switch (S1), the negative input terminal is connected to the source of the VI conversion module and the NMOS transistor (NM1), and the output terminal is connected to the gate of the NMOS transistor (NM1).

3. The high-precision absolute value circuit according to claim 2, characterized in that, The VI conversion module includes: a first resistor (R1); one end of the first resistor (R1) is connected to a first level voltage V1, and the other end is connected to the source of the NMOS transistor (NM1).

4. The high-precision absolute value circuit according to claim 2, characterized in that, The IV conversion module includes: a second resistor (R2); one end of the second resistor (R2) is connected to the drain of NM3; the other end is connected to the second level voltage V2.

5. The high-precision absolute value circuit according to claim 2, characterized in that, The comparator is used to compare the input voltage signal and control the on and off of the first and second switching modules based on the comparison result. When the input voltage Vin>0: the comparator output is 1, the second switch (S2) is turned on, and the first switch (S1) and the second switch module are turned off; Input voltage Vin < 0: The comparator output is 0, the second switch (S2) is turned off, and the first switch (S1) and the second switch module are turned on.

6. The high-precision absolute value circuit according to claim 2, characterized in that, When the input voltage is negative, the output voltage of the circuit is: in, Input voltage; The converted voltage; , These are the voltage levels of the VI conversion module and the IV conversion module, respectively. , These are the width-to-length ratios of the two PMOS transistors in the P-type current mirror module. , These are the width-to-length ratios of the two NMOS transistors in the N-type current mirror module, respectively. and These are the resistance values ​​of the resistors in the VI conversion module and the IV conversion module, respectively.

7. The high-precision absolute value circuit according to claim 6, characterized in that, The circuit is implemented using SMIC 55nm CMOS technology.

8. A high-precision absolute voltage output method, characterized in that, The method includes: using the high-precision absolute value circuit according to any one of claims 1-7 to output the absolute value of the voltage.

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