Frequency-adjustable sine wave generation circuit based on memristor

Abstract

The invention discloses a frequency-adjustable sine wave generation circuit based on a memristor. The frequency-adjustable sine wave generation circuit comprises a single-chip microcomputer, a sine wave generation circuit, a memristor regulation and control circuit and an upper computer Uart serial port communication circuit. Firstly, a single-chip microcomputer receives sine wave frequency input by an upper computer through a Uart serial port and calculates a target resistance value of a memristor; secondly, the single-chip microcomputer disconnects the power supply of the sine wave generation circuit, and the sine wave generation circuit stops working at the moment; then, the single-chip microcomputer controls the memristor regulation and control circuit to start to work, the resistance value of the memristor changes, when the memristor reaches the target resistance value, the memristor regulation and control circuit stops working, the resistance value of the memristor stops changing, the single-chip microcomputer recovers the power supply of the sine wave generation circuit, and the sine wave generation circuit starts to output sine wave signals; and finally, the single-chip microcomputer receives a sine wave signal fed back by the output end of the sine wave generation circuit and measures the frequency of the sine wave signal, thereby realizing closed-loop monitoring of the sine wave signal.

Description

Technical Field

[0001] The invention relates to a frequency-adjustable sine wave generating circuit, in particular to a frequency-adjustable sine wave generating circuit based on a memristor. Background Art

[0002] The sine wave generating circuit provides a sine wave signal source with a stable frequency, which can be used in various electronic devices and systems. In the field of measurement, the sine wave generating circuit is used to generate a sine wave test signal, such as measuring the index parameters of the amplifier circuit; in the field of communication, the sine wave generating circuit is used to generate a carrier signal to modulate and demodulate the communication signal; in the field of audio processing, the sine wave generating circuit is used to generate an audio signal for speech synthesis and sound processing; in the field of control systems, the sine wave generating circuit is used to generate a control signal, such as using a sine wave signal to control the torque of a brushless DC motor. Therefore, the sine wave generating circuit is widely used in various fields of the electronics industry.

[0003] Traditional sine wave generating circuit such as Figure 1 As shown, it consists of capacitors C1, C2, diodes D1, D2, resistors R1-R5 and operational amplifier OP1, and generates a sine wave signal through circuit self-oscillation. Resistor R1 and capacitor C1 are connected in series, and resistor R2 and capacitor C2 are connected in parallel, which together form an RC series-parallel frequency selection circuit; diode D1 and diode D2 form an amplitude stabilization circuit; resistors R3-R5 and operational amplifier OP1 form an amplification circuit; the positive and negative power supplies of operational amplifier OP1 are V CC and V EE . A tiny disturbance signal is generated at the moment of power-on, so the operational amplifier OP1 generates a very small output signal, and contains a rich frequency. The amplifier circuit ensures that the sine wave generating circuit can have a process from starting to gradually increasing the amplitude until dynamic balance. The function of the RC series-parallel frequency selection circuit is to introduce positive feedback, so that the input signal of the amplifier circuit is equal to the feedback signal, satisfying the oscillation condition, and at the same time only allowing a single-frequency sine wave signal to generate positive feedback, so the amplifier circuit outputs a single-frequency sine wave signal and the amplitude continues to increase until dynamic balance. The function of the amplitude stabilization circuit is to rely on the nonlinearity of the transistor to stabilize the output sine wave voltage. Under the joint action of the amplifier circuit, the RC series-parallel frequency selection circuit and the amplitude stabilization circuit, the sine wave generating circuit outputs a sine wave signal with stable amplitude and frequency. The frequency of the sine wave signal can be jointly determined by the resistors R1, R2, capacitors C1 and C2 in the RC series-parallel frequency selection circuit.

[0004] The traditional sine wave generating circuit uses a coaxial potentiometer or a digital potentiometer to change the size of the resistor in the RC series-parallel frequency selection circuit, so as to achieve adjustable frequency of the output sine wave signal; however, the coaxial potentiometer has the disadvantages of large size, complex mechanical structure and low precision, while the digital potentiometer has the disadvantages of slow speed, resistance value greatly affected by temperature and high power consumption.

[0005] At present, memristors are the fourth basic electronic component besides resistors, inductors and capacitors. Memristors have resistance plasticity, and their resistance can change according to the voltage applied to the memristor, and remain unchanged after power failure; the resistance plasticity of memristors is directional, that is, applying opposite voltages can cause the resistance to change in the opposite direction; at the same time, the characteristic of voltage threshold memristors is that the resistance of the memristor changes only when the voltage across its two ends exceeds the threshold. In addition, memristors also have the advantages of fast speed, nanometer size, low power consumption, high reliability, compatibility with CMOS and easy large-scale integration. Therefore, memristors are suitable for hardware circuit design and can better replace traditional resistors, coaxial potentiometers and digital potentiometers.

[0006] Based on the plasticity of the resistance value of the memristor, the present invention proposes a frequency-adjustable sine wave generating circuit based on the memristor, which realizes the continuous adjustment of the frequency of the sine wave output signal, while also meeting the design requirements of high precision, small size, low power consumption and high speed. Summary of the invention

[0007] The present invention proposes a frequency-adjustable sine wave generating circuit based on a memristor, which uses a voltage threshold type memristor to replace the coaxial potentiometer or digital potentiometer in a traditional sine wave generating circuit, and adopts a single-chip microcomputer to control the memristor control circuit to achieve continuous adjustment of the resistance value of the memristor, thereby making the frequency of the sine wave signal output by the sine wave generating circuit continuously adjustable.

[0008] The present invention is implemented through the following technical scheme: a frequency-adjustable sine wave generating circuit based on a memristor, which comprises a single-chip microcomputer, a sine wave generating circuit, a memristor regulating circuit and a host computer Uart serial port communication circuit.

[0009] First, the single-chip microcomputer receives the sine wave frequency input by the host computer through the Uart serial port, and the target resistance value of the memristor is calculated by the internal program of the single-chip microcomputer; secondly, the single-chip microcomputer disconnects the power supply of the operational amplifier OP1 in the sine wave generating circuit, so the sine wave generating circuit stops working; then, the single-chip microcomputer controls the memristor control circuit to start working, and the resistance value of the memristor changes. When the memristor reaches the target resistance value, the memristor control circuit controlled by the single-chip microcomputer stops working, and the power supply of the operational amplifier OP1 in the sine wave generating circuit is restored. At this time, the resistance value of the memristor is fixed, and the sine wave generating circuit starts to output a sine wave signal; finally, the single-chip microcomputer receives the sine wave signal fed back from the output end of the sine wave generating circuit, measures the frequency of the sine wave signal, realizes closed-loop monitoring of the output sine wave signal, and further controls the output of the sine wave signal with an ideal frequency value.

[0010] The sine wave generating circuit consists of memristors M1, M2, resistors R1-R3, capacitors C1, C2, and a positive power supply V CC , negative power supply V EE , diodes D1, D2, NMOS tubes Q6, Q7 and operational amplifier OP1, and works on the principle of self-excited oscillation. The positive power supply pin of operational amplifier OP1 is connected to the source of NMOS tube Q7, and the drain of NMOS tube Q7 is connected to the positive power supply V CC The negative power supply pin of the operational amplifier OP1 is connected to the source of the NMOS tube Q6, and the drain of the NMOS tube Q6 is connected to the negative power supply V EE The gates of NMOS tubes Q6 and Q7 are connected to the P1.1 and P1.2 pins of the microcontroller respectively. The microcontroller controls the power supply of the operational amplifier OP1 through NMOS tubes Q6 and Q7. When the sine wave generating circuit is working normally, the voltage across the memristors M1 and M2 is lower than its threshold value, so the resistance of the memristors M1 and M2 remains unchanged. The memristor M1 and the capacitor C1 are connected in series, and the memristor M2 and the capacitor C2 are connected in parallel, which together form an RC series-parallel frequency selection circuit. The diodes D1 and D2 form an amplitude stabilization circuit, and the resistors R1-R3 and the operational amplifier OP1 form an amplification circuit. A small disturbance signal is generated at the moment of power-on, so the operational amplifier OP1 generates a very small output signal with rich frequencies. The amplification circuit ensures that the circuit can have a process from oscillation to gradual increase in amplitude until dynamic balance. The RC series-parallel frequency selection network introduces positive feedback, making the input signal of the amplifier circuit equal to the feedback signal, and only generates positive feedback for a single-frequency sine wave signal. Therefore, the amplifier circuit outputs a single-frequency sine wave with increasing amplitude. Due to the nonlinear characteristics of the transistor and the limitation of the power supply voltage, the sine wave output by the amplifier circuit eventually maintains a stable state, that is, the sine wave generating circuit generates a sine wave signal with stable amplitude and frequency. The frequency of the sine wave signal can be changed by changing the resistance of the memristors M1 and M2.

[0011] The memristor control circuit consists of a voltage source +V D , Voltage Source -V D The MCU outputs a high level or a low level through the IO pin to control the conduction or shutdown of the NMOS tube connected to it. Voltage source +V D and voltage source -V D The positive electrode of the memristor is connected in parallel with the NMOS tube, the negative electrode of the memristor M1 is grounded through the NMOS tube, and the negative electrode of the memristor M2 is directly grounded. The single chip control connects the voltage source +V D When the NMOS tube is turned on and the memristor is grounded, the voltage at the positive electrode of the memristor exceeds the positive threshold voltage, and the resistance of the memristor decreases. D When the NMOS tube is turned on and the memristor is grounded, the voltage at the positive electrode of the memristor exceeds the negative threshold voltage, and the resistance of the memristor increases. The microcontroller controls the conduction time of the NMOS tube, and the resistance change of the memristor is related to the magnitude and time of the applied voltage, so the microcontroller can control and adjust the resistance of the memristor.

[0012] The sine wave signal output by the sine wave generating circuit is transmitted to the microcontroller through a feedback loop. The microcontroller detects the frequency of the sine wave signal to achieve precise regulation and closed-loop monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a traditional sine wave generating circuit diagram.

[0014] Figure 2 This is a frequency-adjustable sine wave generating circuit based on a memristor in the present invention.

[0015] Figure 3 Graph showing the change in resistance of memristors M1 and M2 in the present invention.

[0016] Figure 4 This is a frequency variation diagram of the sinusoidal wave signal in the present invention. DETAILED DESCRIPTION

[0017] In order to make the technical solutions, objectives and advantages of the present invention more clear, the specific implementation process of the present invention is further described in detail below with reference to the accompanying drawings.

[0018] like Figure 2 As shown, the present invention proposes a frequency-adjustable sine wave generating circuit based on a memristor, which is composed of a single-chip microcomputer, a sine wave generating circuit, a memristor control circuit and a host computer Uart serial port communication circuit.

[0019] like Figure 2As shown, the single-chip microcomputer adopts a 51 series single-chip microcomputer with ADC function and Uart function, the GND pin of the single-chip microcomputer is grounded, the VCC pin of the single-chip microcomputer is connected to a 5V voltage source, the P1.0 pin of the single-chip microcomputer is connected to the output sine wave signal, the P1.1 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q6, the P1.2 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q7, the P1.3 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q2, the P1.4 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q1, the P1.5 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q5, the P1.6 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q4, and the P1.7 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q3.

[0020] like Figure 2 As shown, the sine wave generating circuit consists of memristors M1, M2, resistors R1, R2, R3, capacitors C1, C2, operational amplifier OP1, positive power supply V CC , negative power supply V EE , diodes D1 and D2. The negative electrode of memristor M1 is connected to one end of capacitor C1, the positive electrode of memristor M1 is connected to the output end of operational amplifier OP1, and the other end of capacitor C1 is connected to the non-inverting input end of operational amplifier OP1; memristor M2 is connected in parallel with capacitor C2, the negative electrode of memristor M2 is grounded, and the positive electrode of memristor M2 is connected to the non-inverting input end of operational amplifier OP1; one end of resistor R1 is grounded, and the other end of resistor R1 is connected to the inverting input end of operational amplifier OP1; resistor R2 is connected to the inverting input end and output end of operational amplifier OP1 respectively; diodes D1 and D2 are connected in reverse parallel, one end is connected to the output end of operational amplifier OP1, and the other end is connected to resistor R3, and the other end of resistor R3 is connected to the inverting input end of operational amplifier OP1. The positive power supply pin of operational amplifier OP1 is connected to the source of NMOS tube Q7, and the negative power supply pin of OP1 is connected to the source of NMOS tube Q6.

[0021] like Figure 2 As shown, the memristor control circuit consists of a voltage source +V D , Voltage Source -V D The sources of NMOS tubes Q1 and Q2 are connected in parallel to the positive electrode of memristor M2, and the drains of Q1 and Q2 are connected to the voltage source +V D and voltage source -V D Connection; the sources of NMOS tubes Q3 and Q4 are connected in parallel to the positive electrode of memristor M1, and the drains of Q3 and Q4 are connected to the voltage source +V D and voltage source -V D The source of NMOS tube Q5 is grounded, and the drain of Q5 is connected to the negative electrode of memristor M1. The drains of NMOS tubes Q7 and Q6 are connected to the voltage source VCC and voltage source V EE connect.

[0022] like Figure 2 As shown, the host computer and the single-chip microcomputer are connected through the Uart serial port. The host computer inputs the required frequency of the sine wave signal into the single-chip microcomputer, and the single-chip microcomputer calculates the resistance value of the memristor corresponding to the sine wave frequency through the internal program.

[0023] The sine wave signal output by the sine wave generating circuit of the present invention is determined by the RC series-parallel frequency selection circuit, and its frequency f The calculation formula can be expressed as: .

[0024] by Figure 2 The circuit shown in the figure is used for simulation verification as an example. The initial resistance values ​​of memristors M1 and M2 in the circuit are set to 10kΩ, the resistance values ​​of resistors R1 are 100kΩ, R2 is 300kΩ, R3 is 400kΩ, and capacitors C1 and C2 are 50nF. The circuit simulation process is as follows: the sine wave generating circuit starts working at 0ms, and then outputs a sine wave signal. At 33.93ms, the power supply of the operational amplifier in the sine wave generating circuit is disconnected, and the sine wave generating circuit stops working; then the single-chip microcomputer controls the memristor control circuit to start working, the resistance values ​​of the two memristors start to change at the same time at 34.93ms, and the resistance values ​​of the two memristors stop changing at the same time at 35.93ms, and the power supply of the operational amplifier of the sine wave generating circuit is restored at the same time, and then the sine wave generating circuit outputs another sine wave signal with a different frequency.

[0025] like Figure 3 As shown, the resistance values ​​of memristors M1 and M2 always remain the same, changing from 10 kΩ to 15 kΩ simultaneously between 34.93 ms and 35.93 ms, and the resistance values ​​of memristors M1 and M2 remain unchanged for the rest of the time.

[0026] like Figure 4 As shown, the sine wave generating circuit starts to oscillate at 2.51ms, and stably outputs a sine wave signal of 318.3Hz after 4 cycles; between 33.93ms and 35.93ms, the MCU controls the sine wave generating circuit to stop working, the circuit does not output a sine wave signal, the memristor control circuit starts to work, and the resistance values ​​of the memristors M1 and M2 change; the sine wave circuit oscillates again at 38.13ms, and stably outputs a sine wave signal of 212.21Hz after 5 cycles, and the frequency of the sine wave signal is consistent with the calculation result of the theoretical formula in

[0023] .

Claims

1. A frequency-adjustable sine wave generating circuit based on a memristor, characterized in that: It includes a single-chip microcomputer, a sine wave generating circuit, a memristor control circuit and a Uart serial port communication circuit of a host computer; wherein, the single-chip microcomputer first receives the sine wave frequency input by the host computer through the Uart serial port, and the target resistance value of the memristor is calculated by the internal program of the single-chip microcomputer; secondly, the single-chip microcomputer disconnects the power supply of the operational amplifier OP1 in the sine wave generating circuit, so that the sine wave generating circuit stops working; then, the single-chip microcomputer controls the memristor control circuit to start working, and the resistance value of the memristor changes. When the memristor reaches the target resistance value, the memristor control circuit controlled by the single-chip microcomputer stops working, and the power supply of the operational amplifier OP1 in the sine wave generating circuit is restored. At this time, the resistance value of the memristor is fixed, and the sine wave generating circuit starts to output a sine wave signal; finally, the single-chip microcomputer receives the sine wave signal fed back from the output end of the sine wave generating circuit, measures the frequency of the sine wave signal, realizes closed-loop monitoring of the output sine wave signal, and further controls the output of the sine wave with an ideal frequency value; The single-chip microcomputer adopts a 51 series single-chip microcomputer with ADC function and Uart function, the GND pin of the single-chip microcomputer is grounded, the VCC pin of the single-chip microcomputer is connected to a 5V voltage source, the P1.0 pin of the single-chip microcomputer is connected to the output sine wave signal, the P1.1 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q6, the P1.2 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q7, the P1.3 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q2, the P1.4 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q1, the P1.5 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q5, the P1.6 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q4, and the P1.7 pin of the single-chip microcomputer is connected to the gate of the NMOS tube Q3; The sine wave generating circuit comprises memristors M1 and M2, resistors R1, R2 and R3, capacitors C1 and C2, an operational amplifier OP1, a positive power supply V CC , negative power supply V EE , diodes D1 and D2; the negative electrode of the memristor M1 is connected to one end of the capacitor C1, the positive electrode of the memristor M1 is connected to the output end of the operational amplifier OP1, and the other end of the capacitor C1 is connected to the non-inverting input end of the operational amplifier OP1; the memristor M2 is connected in parallel with the capacitor C2, the negative electrode of the memristor M2 is grounded, and the positive electrode of the memristor M2 is connected to the non-inverting input end of the operational amplifier OP1; one end of the resistor R1 is grounded, and the other end of the resistor R1 is connected to the inverting input end and the output end of the operational amplifier OP1; the diodes D1 and D2 are connected in reverse parallel, and one end is connected to the output end of the operational amplifier OP1, and the other end is connected to the resistor R3, and the other end of the resistor R3 is connected to the inverting input end of the operational amplifier OP1; the positive power supply pin of the operational amplifier OP1 is connected to the source of the NMOS tube Q7, and the negative power supply pin of OP1 is connected to the source of the NMOS tube Q6; The memristor control circuit is composed of a voltage source +V D , Voltage Source -V D The source of NMOS tubes Q1 and Q2 is connected in parallel with the positive electrode of memristor M2, and the drain of Q1 and Q2 is connected to the voltage source +V D and voltage source -V D Connection; the sources of NMOS tubes Q3 and Q4 are connected in parallel to the positive electrode of memristor M1, and the drains of Q3 and Q4 are connected to the voltage source +V D and voltage source -V D The source of NMOS tube Q5 is grounded, the drain of Q5 is connected to the negative electrode of memristor M1, and the drains of NMOS tubes Q7 and Q6 are connected to the voltage source V CC and voltage source V EE connect; The host computer and the single-chip microcomputer are connected via a Uart serial port. The host computer inputs the required frequency of the sine wave signal into the single-chip microcomputer, and the single-chip microcomputer calculates the resistance value of the memristor corresponding to the sine wave frequency through an internal program.

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