Waveform Generator Research Articles

Design of a Current-Mode Trapezoidal Waveform Generator in High-Voltage SOI Technology with Modifications Based on Safe Operating Area Limits

Integrated circuits are the core building components of virtually all communication systems. Wireless communication systems are becoming increasingly common. They require specialized transmission components to reduce electromagnetic interference. This paper presents the design of a trapezoidal waveform generator intended for generation of waveforms with limited level and spectrum of radiated interference This limitation is important because the discussed circuit is a high-voltage function block that can drive the output antenna with relatively high-power pulses. The introduced design is based on a mix of low- and high-voltage devices; however, most of them operate in low-voltage steady and near steady conditions. The implemented design flow includes safe operating area controls, which result in the implementation of a set of overvoltage devices. The designed generator provides means of frequency and slew rate control and can produce high-quality output waveforms. The results show that this type of design can be further optimized for generating waveforms with a limited range of slew rate values. Moreover, this paper presents some operational aspects and phenomena that must be addressed to provide a design that can be practically implemented in modern high-voltage integrated circuits.

Design of Double Strains in Triboelectric Nanogenerators toward Improving Human Behavior Monitoring.

Triboelectric nanogenerators (TENGs) offer a convenient means to convert mechanical energy from human movement into electricity, exhibiting the application prospects in human behavior monitoring. Nevertheless, the present methods to improve the device monitoring effect are limited to the design of a triboelectric material level (control of electron gain and loss ability). As compared with reported work, we improve the monitoring effect of TENG-based tactile sensors by optimizing the structure of the electrode/triboelectric material interface by means of a multiple strains mechanism. Cu@Ni double-clad waste woven fabrics are used as electrodes, which are characterized by a structure with a large number of pores formed between the fibers, greatly increasing the specific surface area of the electrode and generating dynamic strain under differentiated stress fields because of their different elastic modulus. To be exact, the resin layer undergoes elastic deformation under 0.64-4.47 kPa external stress and a new deformation generates at the electrode/triboelectric material interface induced by Cu@Ni double-clad woven fabrics slip under 4.47-63.84 kPa external stress, resulting in the accumulation of triboelectric charges on the PDMS surface. The establishment of multiple strains in triboelectric material further facilitates the generation of distinct triboelectric signal waveforms that are easily distinguishable by its amplitude and peak form. Besides, combined with deep machine learning and the triboelectric effect, in an open setting, the identification accuracy of five distinct behaviors approaches 100%. This provides a new pathway for enhancing identification accuracy of a TENG-based tactile sensor.

Tunable Multi-Band Linear Frequency Modulated Waveforms Generation Based on Self-Subharmonic Modulating of Optically Injected Semiconductor Laser

Tunable Multi-Band Linear Frequency Modulated Waveforms Generation Based on Self-Subharmonic Modulating of Optically Injected Semiconductor Laser

Efficient hardware implementation of ROM-free LFM waveform generation for real-time reconfigurable software-defined radar

Abstract This paper presents a novel method for generating Linear Frequency Modulation (LFM) waveforms. Conventional Look-Up Table (LUT)-based method require large storage resources, especially in high-resolution, multi-mode radar systems. To address this issue, we propose a ROM-free, real-time LFM waveform generator. It uses the fourth-order Runge-Kutta (RK-4) method to solve differential equations for the in-phase and quadrature components. The proposed approach dynamically generates LFM waveforms using only parameters such as pulse width, bandwidth, and sampling rate, eliminating the need for pre-calculated waveforms and LUTs. This method completely removes storage requirements, enabling faster synthesis times and achieving minimal latency. The generator’s performance is validated through simulation and FPGA implementation using a full hardware description language. Results confirm its effectiveness, making it a strong candidate for advanced radar systems that demand high performance with limited hardware resources.

Photonic Generation of Multiband and Multi-Format Chirped Microwave Waveforms Based on an Optoelectronic Oscillator

We propose and demonstrate a microwave photonic system to generate multiband and multi-format microwave waveforms based on an actively mode-locked optoelectronic oscillator (AML-OEO) using a dual-polarization dual-drive Mach–Zehnder modulator (DPol-DDMZM). In the proposed system, the upper DDMZM is injected by two baseband single-chirped signals, and the lower DDMZM is biased to realize single-sideband (SSB) modulation using a 90° hybrid coupler. The lower DDMZM is also used to construct an AML-OEO loop, which outputs microwave frequency comb signals. By setting the phase difference in the applied two single-chirped signals, multiband up-, down-, and dual-chirped microwave signals are successfully generated. Furthermore, the tunability of the system can be realized by adjusting the frequency and power of the injection signal in the AML-OEO loop, the passband of the electrical filter, and the chirp rate of the single-chirped signal. The proposed scheme is theoretically analyzed and experimentally verified.

Enhancing power quality in wireless DC power supplies through active power filtering: A computer simulation approach

This paper presents a computer simulation model for a high-power factor wireless DC power supply system, integrating an active power filter (APF) at the rectifier stage on the transmitter side using a rectifier boost technique. The APF, employing a MOSFET switch regulated by active pulse width modulation (APWM) within a current control loop, addresses pulsating and distorted AC supply currents caused by non-linear loads. A robust closed-loop control mechanism, including a subtractor circuit, proportional-integral (PI) controller, and comparator, ensures the generation of a continuous sinusoidal waveform synchronized with the supply voltage. The model utilizes a high-frequency inverter to convert DC to AC, which is then wirelessly transmitted via wireless power transfer (WPT) technology and converted back to DC by a high-frequency rectifier. MATLAB/Simulink simulation results show a significant reduction in total harmonic distortion (THD) of the AC supply current, complying with IEEE 519 standards. Selected results are presented to verify the proposed method's effectiveness in reducing harmonic distortions and enhancing power quality. This study highlights the advantages of WPT in scenarios where traditional wired connections are impractical and underscores the potential of this system for real-world applications, particularly in developing high-power factor wireless DC power supply systems.

Multi-Band Multi-Format Switchable Microwave Waveforms Generation Based on an AML-OEO

Multi-Band Multi-Format Switchable Microwave Waveforms Generation Based on an AML-OEO

Radar and communication integration under FPGA platform: real-time waveform generation with time division multiplexing and waveform sharing strategy

Abstract The integration of radar and communication technologies is gaining prominence in electronic information systems. This paper explores advanced waveform strategies—LFM (Linear Frequency Modulation) + MSK (Minimum Shift Keying) based on time-division multiplexing and LFM-MSK utilizing waveform sharing. These methods enhance spectrum efficiency and system capabilities in detecting targets and transmitting data reliably amidst complex environments. Based on the FPGA (Field Programmable Gate Array) platform, this study proposes real-time waveform generation methods for integrated radar communication waveforms, specifically LFM+MSK and LFM-MSK. It focuses on discussing FPGA implementation solutions for these methods and validates their effectiveness. This research addresses a critical gap in the field and provides practical insights for radar communication integration systems.

Thermally Stable Ag2Se Nanowire Network as an Effective In‐Materio Physical Reservoir Computing Device

AbstractThe artificial intelligence (AI) paradigm shifts from software to implementing general‐purpose or application‐specific hardware systems with lower power requirements. This study explored a material physical reservoir consisting of a material random network, called in‐materio physical reservoir computing (RC) to achieve efficient hardware systems. The device, made up of a random, highly interconnected network of nonlinear Ag2Se nanojunctions as reservoir nodes, demonstrated the requisite characteristics of an in‐materio physical reservoir, including but not limited to nonlinear switching, memory, and higher harmonic generation. The power consumption of the in‐materio physical reservoir is 0.07 nW per nanojunctions, confirming its highly efficient information processing system. As a hardware reservoir, the devices successfully performed waveform generation tasks. Finally, a voice classification by an in‐materio physical reservoir is achieved over 80%, comparable to an RC software simulation. In‐materio physical RC with rich nonlinear dynamics has huge potential for next‐generation hardware‐based AI.

Feedback switching control of a walking piezoelectric actuator for trajectory tracking

Abstract This paper proposes a feedback switching control (FSC) scheme for a Walking Piezoelectric Actuator (WPA) to track a time-varying trajectory. A WPA has two feet with each foot integrated with a clamp and shear Piezoelectric Stack Actuators (PSAs). The first foot pushes the stage translator a step forward when clamped while the second foot is reset and retracted; subsequently, ‘foot switching’ occurs; as a result, the second foot is clamped to push the translator to make a next step forward and the first foot is reset and retracted. To make sure that the translator is always controlled in closed-loop no matter which foot is clamped, the FSC scheme is proposed. It consists of a clamping waveform generator which converts the trajectory into control signals for the clamp PSAs of the two feet and a feedback controller which provides control signals for the two shear PSAs of the feet. Experimental results show that the proposed control scheme achieves a tracking error of 0.028 µm for a constant velocity trajectory, which is a 75% reduction compared to the 0.113 µm of waveform-based control with ILC compensation in literature.

Design of a High-Voltage Arbitrary Waveform Generator Using a Modular Cascaded H-Bridge Topology

As the integration of renewable energy sources into the grid increases, the insulation systems of grid components such as transformers and switchgear encounter significant challenges due to the transients and harmonics generated by power-electronic-based converters. A test generator capable of replicating these component stresses is essential to accurately evaluate these insulation systems under real-grid conditions. This paper proposes a modular cascaded H-bridge-based high-voltage arbitrary waveform generator, prototyped with three stages to generate customized waveforms (triangular, sawtooth, pulse, and complex) up to 8 kV. The H-bridge modules are designed using Si MOSFETs with a maximum blocking voltage of 4.5 kV. The input to the HV H-bridge module is provided by a 10 kV medium-frequency transformer, whose design is described with a focus on the insulation system and winding configuration. This transformer is driven by a zero-voltage switching driver. This arbitrary waveform generator excels in several aspects, including a straightforward design procedure, compact size, high voltage capability, ease of integration, and cost.

A PAPR correction scheme for LoRa self‐jamming waveforms

AbstractA LoRa self‐jamming scheme that enables secure and covert communications by adding jamming symbols when transmitting is proposed. The scheme has been validated in simulations. The work is continued by evaluating the scheme on real‐world software defined radio (SDR) equipment. Experiments immediately showed that a demodulation is impossible as the received signal is highly distorted. This comes from the fact that adding symbols at transmission actually generates high peak‐to‐average power ratio (PAPR) preventing proper waveform generation by the equipment's hardware. This paper presents a PAPR correction scheme that modifies the waveform. The properties of this modified waveform are analysed and the performances are assessed in simulations with realistic time and frequency synchronization assumption. For the ideal 0 dB PAPR corrected output, the SER performances are close to that of a legacy LoRa communication, while preserving the physical layer security capabilities of the self‐jamming scheme. It is finally shown that our PAPR correction scheme effectively recovers the self‐jamming properties on SDR devices.

Characterisation and synchronisation of a netted software defined radio radar

AbstractThe present work intends to characterise the combination of two netted software defined radios (SDR) and different radio frequency (RF) front‐ends installed in them, together with a two‐stratum time dissemination and synchronisation system. A modified implementation of the Network Time Protocol is used as coarse event synchronisation for either SDR back‐end. The White rabbit light embedded node implementation of the commonly known white rabbit synchronisation system (IEEE 1588 PTP‐2019) or arbitrary wave form generators are used as fine time dissemination system for either SDR. The resulting netted transceiver system is intended to compose a demonstrator for proof‐of‐concept experiments. The findings presented in this article show that the chosen combination of hardware and software is suitable for radar applications operating within L‐, S‐ and C‐bands. A channel coherency throughout the network with a relative modified Allan deviation of less than 80 fs for averaging intervals of 1 s, a phase noise better than −118 dBc/Hz at 10 Hz frequency offset and a fractional frequency lower than was measured. Within a single transceiver node, a fractional frequency lower than and phase noise of −124 dBc/Hz at 10 Hz frequency offset were measured as well. Multistatic radar systems exploit wide spatial diversity to enhance target detection and tracking, albeit with increased complexity when compared to a monostatic configuration. To exploit these benefits, all participating transceiver nodes within the netted radar need to synchronise to a common time base . The achieved synchronisation level increases the accuracy with which the chain of timed events at the transmitter and at the receiver side occur, intending to maximise the signal‐to‐noise ratio available at the receiver. The Universal software radio peripheral model X310 with two different daughterboard models as RF front‐end was used as SDR on either radar node. A network combining data and synchronisation purposes allowed the radar nodes under test to operate synchronously. The two‐stratum synchronisation system used glass fibres between 2 m and 5 km of length or coaxial cables with 2 m in length for network traffic, time and frequency dissemination purposes. The multiple RF front‐ends were stimulated by means of arbitrary waveform generators with calibrated traceability. Up‐chirp and sinusoid waveforms were used as stimuli for measuring the offset of either channel with regards of to ultimately estimate the achievable coherency limits of the system under test. Both analogue and digital evaluation methods were considered.

Experimental study of polyurethane rubber with half-sine waveform generator

Abstract Impact mechanics environmental testing technology is booming. Polyurethane rubber, as a typical semi-sinusoidal waveform generator, is particularly important to understand its stiffness performance. This paper presents an experimental investigation utilizing a pneumatic impact testing machine to evaluate the performance of polyurethane rubber waveform generators, varying in both hardness and height. By recording their compression under varying impact pressures, as well as the rebound height of the table and the corresponding velocity changes, we observed that the data generated by the 60mm thick waveform generator exhibited greater regularity. Notably, these data adhered to the principle that increased hardness correlates with decreased compression and reduced rebound height of the table. Additionally, we successfully designed an initial prototype of a rebound collision acceleration amplifier, which, under an impact pressure of merely 0.038MPa, achieved an impressive impact acceleration of nearly 2700g, accompanied by a smoother half-sine waveform curve.

Simultaneous Photonics Generation of Multiple Chirp Rate Microwave Waveform With Manifold Frequency Multiplying Capability by Using Triple Parallel Mach-Zehnder Modulators

Simultaneous Photonics Generation of Multiple Chirp Rate Microwave Waveform With Manifold Frequency Multiplying Capability by Using Triple Parallel Mach-Zehnder Modulators

SiGe high-frequency pulse-width modulation for low-noise applications

This paper details the first-known experimental observation of pulse-width modulation at 100 MHz using silicon-germanium HBT technology. By performing pulse-width modulation (PWM) at a higher frequency, undesired harmonic-components—which are interpreted as noise—are likewise raised to higher frequencies. In doing so, the noise generated by the PWM controller can be raised to frequencies at which it is no longer relevant. Noise-free operation is guaranteed below the operating frequency of the PWM controller, so long as the semiconductor technology supports high-frequency waveform generation. Such capability is readily provided by modern silicon-germanium HBT technology. The paper also provides an integrated-circuit design with additional flexibility for the end user, with simulated performance results.

Generative adversarial networks for whispered to voiced speech conversion: a comparative study

Generative Adversarial Networks (GANs) have demonstrated promising results as end-to-end models for whispered to voiced speech conversion. Leveraging non-autoregressive systems like GANs capable of performing conditional waveform generation eliminates the need for separate models to estimate voiced speech features, and leads to faster inference compared to autoregressive methods. This study aims to identify the optimal GAN architecture for the whispered to voiced speech conversion task by comparing six state-of-the-art models. Furthermore, we present a method for evaluating the preservation of speaker identity and local accent, using embeddings obtained from speaker- and language identification systems. Our experimental results show that building the speech conversion system based on the HiFi-GAN architecture yields the best objective evaluation scores, outperforming the baseline by ∼ 9% relative using frequency-weighted Signal-to-Noise Ratio and Log Likelihood Ratio, as well as by ∼ 29% relative using Root Mean Squared Error. In subjective tests, HiFi-GAN yielded a mean opinion score of 2.9, significantly outperforming the baseline with a score of 1.4. Furthermore, HiFi-GAN enhanced ASR performance and preserved speaker identity and accent, with correct language detection rates of up to ∼ 98%.

Magneto-acousto-electrical tomography based on frequency response compensated linearly frequency-modulated signal stimulation

Objective. In magneto-acousto-electrical tomography (MAET), linearly frequency-modulated (LFM) signal stimulation uses much lower peak voltage than the spike pulse stimulation, lengthening the operation life of the transducer. However, due to the uneven frequency responses of the transducer, the low-noise amplifier (LNA), and the bandpass filter (BPF), MAET using LFM signal stimulation suffers from longitudinal resolution loss. In this paper, frequency response compensated linearly frequency-modulated (FRC-LFM) signal stimulation is investigated to resolve the problem.Approach. The physical model of measurement of the frequency responses of the transducer and the cascading module of the detection electrodes, the LNA, and the BPF is constructed. The frequency responses are approximated by fitting a curve to the measurement data. The frequency response compensation function is set to the reciprocal of the product of the frequency responses. The digital FRC-LFM signal is generated in MATLAB and converted to analog signal through an arbitrary waveform generator. Two groups of MAET experiments are designed to confirm the performance of the FRC-LFM signal stimulation. Pure agar phantom with rectangular through-holes and agar phantom with pork tissue inclusion serve as the samples.Main results. The pulse-compressed magneto-acousto-electrical signal obtained using FRC-LFM stimulation has narrower main-lobe than that obtained using LFM excitation, although the signal to noise pulse interference ratio of the former is little lower than that of the latter, which is due to the limitation of the power amplifier. FRC-LFM also proves to be an effective method to utilize the frequency outside the working band of the transducer in MAET.Significance. The method in this study compensates for the longitudinal resolution loss due to the uneven frequency responses. Combining with high-capability power amplifier and high-performance LNA, the MAET using FRC-LFM signal stimulation can potentially achieve high longitudinal resolution and high sensitivity, advancing MAET toward the clinical application.

Real-Time Reconfigurable Radio Frequency Arbitrary-Waveform Generation via Temporal Pulse Shaping with a DPMZM and Multi-Tone Inputs

Benefitting from a large bandwidth and compact configuration, a time-domain pulse-shaping (TPS) system provides possibilities for generating broadband radio frequency (RF) arbitrary waveforms based on the Fourier transform relationship between the input–output waveform pair. However, limited by the relatively low sampling rate and bit resolution of an electronic arbitrary-waveform generator (EAWG), the diversity and fidelity of the output waveform as well as its reconfiguration rate are constrained. To remove the EAWG’s limitation and realize dynamic real-time reconfiguration of RF waveforms, we propose and demonstrate a novel approach of RF arbitrary-waveform generation based on an improved TPS system with an integrated dual parallel Mach–Zehnder modulator (DPMZM) and multi-tone inputs. By appropriately adjusting the DC bias voltages of DPMZM and the power values, as well as the center frequencies of the multi-tone inputs, any desired RF arbitrary waveform can be generated and reconfigured in real time. Proof-of-concept experiments on the generation of different user-defined waveforms with a sampling rate up to 27 GSa/s have been successfully carried out. Furthermore, the impact of modulation modes and higher-order dispersion on waveform fidelity is also discussed in detail.

Semiconductor optical amplifiers as an optical arbitrary waveform generator for high-energy laser systems.

A simple and straightforward technique is presented as a novel temporally controllable front-end for nanosecond very-high energy laser systems. It is based on an original utilization of a semiconductor optical amplifier (SOA) used as an intensity modulator. The essential characteristics of the component are analyzed in order to evaluate potential limitations. Various parameters of interest for standard operation are displayed, demonstrating its usability and its effectiveness. We demonstrate arbitrary and controllable pulse temporal profiles with duration ranging from 1 nanosecond to 100 nanoseconds and a temporal precision of 1.1 ns. A high extinction ratio is also achieved ensuring a modulation contrast up to 53 dB. The SOA is then integrated into an existing operating system in an ultra-compact, reliable all-fibered system. It is used to seed a 2*200 J laser system, exhibiting excellent performance, and validating its usability under operation conditions without any detrimental effects.