Memristor base frequency shift keying modulator

Abstract

The invention relates to a memristor fundamental frequency shift keying modulator, the modulator comprises a modulation unit and a carrier generation unit which are connected in series, the modulation unit comprises a plurality of MOSFETs with different width-to-length ratios, the source electrode of each MOSFET is connected with a bias voltage, the drain electrode of each MOSFET is connected with a series node, n MOSFETs are arranged, the grid electrode of the ith MOSFET is connected with the ith binary input end bi, and the grid electrode of the ith binary input end bi is connected with the carrier generation unit. The series connection node is connected with a carrier generation unit, the carrier generation unit comprises a negative differential memristor, one end of the negative differential memristor is connected with the series connection node, the other end of the negative differential memristor is grounded, and the width-to-length ratios of the n MOSFETs are different from one another. Compared with the prior art, the method has the advantages of eliminating a conversion interface between a digital domain and an analog domain and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of frequency shift keying modulators, and in particular to a memristor-based frequency shift keying modulator. BACKGROUND

[0002] With the rise of industries such as industrial automation, healthcare, and smart agriculture, the wireless Internet of Things is developing rapidly, triggering the demand for data acquisition and transmission. Typically, wireless Internet of Things hardware deployments utilize wireless sensor networks as the data acquisition layer, enabling real-time data transmission between various scenarios by facilitating wireless communication between intelligent devices and remote central clouds in low-frequency bands. In this process, sensor data is converted into radio signals through an antenna after undergoing analog-to-digital conversion, preprocessing, and modulation operations. However, digital binary signals lack an equivalent direct physical quantity that can be described using wave propagation equations, resulting in a sharp conversion interface between the digital and analog domains during modulation. Although traditional modulators are typically composed of digital-to-analog converters and carrier generation units for converting digital inputs into modulated signals carrying information. The physical separation between the digital processing unit and the analog transmission module inherently leads to a trade-off between speed, power, and accuracy during the conversion process.

[0003] Documents Wang, Cong, et al. Nature Electronics 6.5 (2023): 381-389. and Liu, Chang, et al. Nature Communications 15.1 (2024): 1523. demonstrate current signal modulation schemes based on memristors, and current modulation schemes based on memristor arrays mostly rely on external carriers and analog-to-digital conversion modules to modulate sensor signals, making it difficult to balance direct digital modulation and carrier generation functions, the conversion interface between the digital and analog domains is sharp, and it is difficult to miniaturize the memristor array. SUMMARY

[0004] The purpose of the present application is to provide a memristor-based frequency shift keying modulator that combines carrier generation and modulation functions based on digital signal modulation, eliminates the conversion interface between the digital and analog domains while generating a local carrier signal.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] A memristor-based frequency shift keying modulator, the modulator comprising a modulation unit and a carrier generation unit connected in series, the modulation unit comprising a plurality of MOSFETs with different width-to-length ratios, the source of each MOSFET being connected to a bias voltage, the drain of each MOSFET being connected to a series node, there being n MOSFETs in total, wherein the gate of the i-th MOSFET is connected to the i-th binary input bi A carrier wave generation unit is connected to the series node, the carrier wave generation unit comprising a negative differential memristor, one end of the negative differential memristor being connected to the series node and the other end being grounded, and the width-length ratios of the n MOSFETs being different from each other.

[0007] Further, the binary input end b i is inputted with 0 or 1, when the binary input end bi is inputted with 0, the i-th MOSFET is turned off, and when the binary input end bi is inputted with 1, the i-th MOSFET is turned on. i

[0008] Further, for two different MOSFETs, if the width-length ratio of one of the MOSFETs is greater than the width-length ratio of the other MOSFET, the current of the MOSFET when turned on is greater than the current of the other MOSFET when turned on.

[0009] Further, for the a-th MOSFET and the b-th MOSFET, if a is greater than b, the width-length ratio of the a-th MOSFET is greater than the width-length ratio of the b-th MOSFET.

[0010] Further, the oscillation signal of the series node is the output of the modulator.

[0011] Further, the negative differential memristor is initially in a high resistance state, and when the voltage applied to the negative differential memristor exceeds a threshold voltage, the negative differential memristor changes from the high resistance state to a low resistance state; and when the voltage applied to the negative differential memristor decreases to below a retention voltage, the negative differential memristor changes from the low resistance state to the high resistance state.

[0012] Further, the negative differential memristor comprises a parasitic capacitor and a memristor body, and the parasitic capacitor and the memristor body are connected in parallel.

[0013] Further, the carrier wave generation unit further comprises a parallel capacitor.

[0014] Further, the parallel capacitor and the negative differential memristor are connected in parallel.

[0015] Further, the negative differential device is a memristor with threshold switching behavior.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] ​The modulation module of the present application is composed of MOSFETs units with different width-length ratios in parallel, and the binary input signal is given to the gate of the MOSFETs to control the switching thereof. The modulation module and the carrier generation unit are connected in series to realize the completed modulator module, and the oscillation signal at the series node is the output of the modulator. With the rise of the potential at the series node, the negative differential resistors switch to the low resistance state when the potential reaches the transition threshold value, and cause the potential to drop; then the device switches back to the high resistance state when the potential reaches the holding voltage, and the capacitor is recharged and outputs the oscillation signal with frequency characteristics at the series node. Under the action of the digital signal, the MOSFETs in the modulation module are selectively opened, which results in different sizes of charging current, thereby modulating the frequency of the oscillation signal. After the corresponding of the digital input bit weight and the width-length ratio of the MOSFETs unit, the modulator can realize the frequency output modulated by the digital input, thereby realizing the frequency shift keying function. When the input signal is all low, the current flowing through the modulation module is minimum; with the input of low bit and high bit as high level, the current increases in turn, and the current is maximum when the input voltage is high. With the increase of the digital input, the frequency of the oscillation output is improved, and a distinguishable frequency range is shown, realizing the control of the digital signal on the analog frequency signal, realizing the modulation of the continuous signal, generating the local carrier signal at the same time, eliminating the conversion interface between the digital domain and the analog domain, and promoting the miniaturization of the integrated modulator. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The principle diagram of the memristor-based modulator of the present application;

[0019] Figure 2 The integrated scheme of the negative differential memristor and the MOSFET;

[0020] Figure 3 The response of the modulation module under binary input;

[0021] Figure 4 The threshold behavior of the negative differential memristor device;

[0022] Figure 5 The basic characteristics of the modulator;

[0023] Figure 6 The modulation output based on continuous alphabet. DETAILED DESCRIPTION

[0024] The present application will be described in detail below in combination with the drawings and specific embodiments. The present embodiment is implemented on the premise of the technical scheme of the present application, and gives a detailed implementation manner and specific operation process, but the protection scope of the present application is not limited to the following embodiments.

[0025] The application provides a memristor-based frequency shift keying modulator, the modulator comprising a modulation unit and a carrier generation unit connected in series, the modulation unit comprising a plurality of MOSFETs with different width-length ratios, the source of each MOSFET being connected to a bias voltage, the drain of each MOSFET being connected to a series node, and there being n MOSFETs in total, wherein the gate of the i-th MOSFET is connected to the i-th binary input b i , the series node being connected to the carrier generation unit, the carrier generation unit comprising a negative differential memristor, one end of the negative differential memristor being connected to the series node and the other end being grounded, and the width-length ratios of the n MOSFETs being different from each other.

[0026] The application provides a frequency shift keying modulation realized by integrating a negative differential memristor and a MOSFET unit. The modulator integrates the functions of carrier generation and digital-to-analog conversion, and can continuously modulate the oscillation frequency based on direct parallel digital input. By assigning MOSFET units with different width-length ratios based on bit weights, continuous frequency shift keying modulation can be realized. The memristor-based frequency shift keying provides an effective solution for direct digital signal modulation, and promotes the development of miniaturized, energy-saving and integrable modulators in Internet of Things applications.

[0027] Figure 1 The negative differential memristor-based frequency shift keying modulator is composed of a modulation module and a carrier generation unit. The carrier generation module is realized by a self-sustaining oscillator constructed by a negative differential memristor; the modulation module is based on MOSFETs with different width-length ratios to realize the adjustment of charging current based on parallel digital input, thereby realizing the output of oscillation signals with different frequencies.

[0028] Device structure: the carrier generation unit is composed of a negative differential memristor and a parallel capacitor. The parallel capacitor can be realized by the parasitic capacitance of the device itself. The modulation module is composed of MOSFETs with different width-length ratios connected in parallel, and the binary input signal is given to the gate of the MOSFET to control the switching thereof. The modulation module and the carrier generation unit are connected in series to realize the completed modulator module, and the oscillation signal of the series node is the output of the modulator.

[0029] Working principle: For the carrier generation unit, a charging current caused by the bias voltage charges the carrier generation unit. As the potential at the series node rises, the negative differential resistive device switches to a low resistance state when the potential reaches its switching threshold, and causes the potential to drop; then the device switches back to a high resistance state when the potential reaches its holding voltage, the capacitor recharges and outputs an oscillation signal with frequency characteristics at the series node. Under the action of the digital signal, the MOSFETs in the modulation module are selectively turned on, which causes charging currents of different sizes, thereby modulating the frequency of the oscillation signal. After the corresponding weights of the digital input bits and the width-length ratios of the MOSFET units are sequentially completed, the modulator can realize a frequency output modulated by the digital input, thereby realizing the function of frequency shift keying.

[0030] Figure 2 Integration scheme for negative differential resistive device and MOSFET:

[0031] Step 1: Take the source electrode of the MOSFET in parallel with the power supply as the bottom electrode, and deposit the negative differential resistive material on it. The negative differential resistive material can be NbO2 (niobium dioxide), VO2 (vanadium dioxide), SiTe (silicon telluride), SiO2:Ag (silver-doped silicon oxide), α-Si:Cu (copper-doped amorphous silicon), α-Si:Ag (silver-doped amorphous silicon), or AM4Q8 (chalcogenide Mott insulator, A = Ga, Ge; M = V, Nb, Ta, Mo; Q = S, Se) mixed material, and materials with volatile threshold transition characteristics can be applied.

[0032] Step 2: Deposit the top electrode on the capacitor film. The electrode material is not limited and can be TiN, Poly-Si, Pd, Pt, W, Cu, Ag, or Au, etc. conductive material.

[0033] Response of the modulation module under binary input: Figure 3 The modulation module composed of parallel MOSFET units should have the current response shown in the figure above. When the input signals are all low, the current flowing through the modulation module is the smallest; as the low bit and high bit inputs are high, the current increases in turn, and the current is the largest when the input voltage is high.

[0034] Threshold behavior of negative differential resistive device: Figure 4 The prepared negative differential resistive device should have the I-V characteristics shown in Figure 4 in the figure. When the voltage applied to the top electrode exceeds the threshold voltage, the volatile resistive device transitions from a high resistance state to a low resistance state. During the voltage back sweep, when the voltage is less than the holding voltage, the device returns to a high resistance state from a low resistance state due to insufficient voltage on the top electrode. It exhibits a bidirectional threshold transition characteristic.

[0035] Basic characteristics of the modulator: Figure 5 The modulator based on the negative differential resistance device is demonstrated to realize the conversion of binary signal to frequency output under direct parallel digital input. With the increase of digital input, the frequency of oscillation output is improved, and a distinguishable frequency range is demonstrated, which meets the signal modulation requirement.

[0036] Continuous modulation output: Figure 6 It is demonstrated in FIG. 6 that after inputting a continuous binary signal containing information, the memristor-based modulator can convert the signal into an oscillation sequence containing frequency characteristics, which proves the modulation ability of the modulator for continuous signals.

[0037] The foregoing detailed description of the application has been presented for purposes of illustration. It is understood in the art that numerous modifications and changes can be made to the preferred embodiment without departing from the underlying inventive concept. Accordingly, it is intended that all such modifications and changes be included within the scope of the application as defined by the following claims.

Claims

1. A memristor-based frequency shift keying modulator, characterized in that: The modulator includes a modulation unit and a carrier generation unit connected in series. The modulation unit includes a plurality of MOSFETs with different width-to-length ratios. The source of each MOSFET is connected to a bias voltage, and the drain of each MOSFET is connected to a series node. Assume that there are n MOSFETs in total, wherein the gate of the i-th MOSFET is connected to the i-th binary input terminal b i The series node is connected to a carrier generating unit, the carrier generating unit includes a negative differential memristor, one end of the negative differential memristor is connected to the series node, and the other end is grounded, and the width-to-length ratios of the n MOSFETs are different.

2. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: The binary input terminal b i The input of the binary input terminal bi is 0 or 1. When the input of the binary input terminal bi is 0, the i-th MOSFET is turned off and the binary input terminal b i When the input is 1, the i-th MOSFET is turned on.

3. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: For two different MOSFETs, if the width-to-length ratio of one MOSFET is greater than the width-to-length ratio of the other MOSFET, the current when the MOSFET is turned on is greater than the current when the other MOSFET is turned on.

4. The memristor-based frequency shift keying modulator according to claim 3, characterized in that: For the a-th MOSFET and the b-th MOSFET, if a is greater than b, the width-to-length ratio of the a-th MOSFET is greater than the width-to-length ratio of the b-th MOSFET.

5. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: The oscillating signal at the series node is the output of the modulator.

6. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: The negative differential memristor is initially in a high-resistance state. When the voltage applied to the negative differential memristor exceeds a threshold voltage, the negative differential memristor changes from a high-resistance state to a low-resistance state. As the voltage applied to the negative differential memristor decreases below a holding voltage, the negative differential memristor changes from a low-resistance state to a high-resistance state.

7. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: The negative differential memristor comprises a parasitic capacitor and a memristor body, wherein the parasitic capacitor and the memristor body are connected in parallel.

8. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: The carrier generation unit further includes a parallel capacitor.

9. The memristor-based frequency shift keying modulator according to claim 7, characterized in that: The shunt capacitor and the negative differential memristor are connected in parallel.

10. The memristor-based frequency shift keying modulator according to claim 1, characterized in that: The negative differential device is a memristor with threshold switching behavior.

Images