Signal Generation Module Research Articles

An Auto-Reconfigurable AC-DC Regulator for Wirelessly Powered Biomedical Implants With 28% Link Efficiency Enhancement

This brief presents an auto-reconfigurable load-dependable ac-dc regulator for wirelessly powered biomedical implants. In wireless power transmission, the peak link efficiency that typically limits the overall system efficiency only occurs at a certain nominal load for a given link design. The proposed reconfigurable ac-dc regulator can automatically switch between doubler and quadrupler rectifier topologies to provide dynamic input impedance matching to the link as the average load current of the regulator varies during system operation, thereby maintaining high-link efficiency over a wide load range. A low-power load modulation signal generator is also developed for closed-loop wireless power control. Implemented in a standard 0.35- $\mu \text{m}$ CMOS process, the proposed rectifier and ac-dc regulator achieve peak power conversion efficiencies of 92.7% and 88.5%, respectively, while operating at 1 MHz. The proposed autoreconfiguration capability of the regulator further provides the link efficiency enhancement of 28% across the wide load power range from 1 to 20 mW.

A novel PWM power amplifier of magnetic suspension spindle control system for micro EDM

Considering the traditional power amplifier has the disadvantage of poor reliability and flexibility, a three-level pulse-width modulation (PWM) power amplifier which is based on a novel field-programmable logic gate array (FPGA) algorithm and hardware solution is proposed. The power amplifier can provide various signals flexibly and realize rapid response of the magnetic suspension spindle in micro-electrical discharge machining (EDM). In this paper, the principle of three-level PWM amplifier with half bridge and full bridge power circuit is introduced. According to different functions, the amplifier is divided into four function modules which include PWM signal generator module, voltage signal convert module, bootstrap drive module, and power bridge module. PWM signal generator module is also divided into four sub-modules in term of a new FPGA algorithm. Voltage signals are converted by high-speed photo coupler HCPL-2630. IR2110S chips are applied to drive the half bridge and full bridge power circuits. According to Kirchhoff voltage law, when the period of PWM signals is 50 μs and the duty cycles are larger than 0.76 and 0.665, the average current of half bridge and full bridge are more than 3 and 4 A; however, the ripple of the half bridge and full bridge are still less than 0.25 and 0.2 A, this advantage is suitable for the control system of magnetic suspension spindle. Test results of the average current and ripple are close to theoretical value. The axial response frequency of the spindle can reach 125 Hz, using this power amplifier and the magnetic suspension spindle, micro EDM can be achieved in Z axis with 1.2 mm stroke.

Design and Implementation of Embedded Processor Based Brushless Motor Drive using Lead Acid Battery as Source with Lithium Ion Capacitor

For the past two decades, Brushless DC motor has become more efficient and robust motor in industrial applications due to their simplicity in structure, reliability, good mechanical properties. The absence of brushes features these motors similar to AC motors whereas their speed performance is nearly equal to that of the DC motors. Thus the combined advantages of AC and DC motors make these motors more efficient in various applications. The design was based on the output equation similar to that of conventional dc machines. This generates high-resolution PWM outputs, used to control the switching pattern of the BLDC Inverter. By varying the PWM signal produced from the microcontroller, the speed of the motor can be varied. The Hall Effect sensing unit gives information about the rotor position and based on this rotor information, switching sequence of the MOSFET is decided. The firing pulses to the gate of the MOSFET are given by the Control Signal Generation Module. Based on the developed model simulation studies are performed in Matlab/Simulink environment and hardware implementation of BLDCM drive using Lead acid battery as source With Lithium ion capacitor system is done and results were analysed using Digital Scope Oscilloscope (DSO) and output Carried Out Sucessfully. DOI: http://dx.doi.org/10.11591/telkomnika.v14i3.7938

Performance of perpendicular magnetic recording with track squeeze using bidirectional pattern-dependent noise prediction detector

In this study, we investigated the performance of perpendicular magnetic recording with squeezed tracks. Based on spinstand signals, we developed a signal generation module to generate the readback signals for tracks of various squeezed track width and bit length. To mitigate the drop in bit error rate (BER) as squeezed track width decreases, we implemented the bidirectional pattern-dependent noise prediction (BiPDNP) detector with low-density parity check codes. To improve the BiPDNP detector over earlier work, we modified the log-likelihood ratio computation. Our results show that our proposed BiPDNP detector improves the bit error rate, and allows smaller squeezed track width and smaller bit length for the same BER performance.

位置・角度検出に用いる位相変調信号生成技術の開発

We carry out a technological examination for improving the positional detection accuracy of position tracking. In this paper, we focus on positional detection technology that uses a scale in which slits are carved at a certain constant period. We develop phase modulation signal generation technology that removes a signal of two frequencies of a one-signal detection track. We report on the detection principle and the results of the principle verification experiment.

FPGA Based PWM of Cascaded Multilevel Voltage Source Inverter

Multilevel inverters have grasped attention in the past few years as power converters in many applications. They are advantageous over the conventional two-level inverters because of the capability of reducing the lower order harmonic contents by increasing the number of levels. Many studies and research have been done for generation of modulating signals for multilevel inverters. Modulation signal generation methods for these inverters include staircase modulation, sine-triangle carrier modulation, space vector modulation etc. Various topologies of multilevel inverter provides several advantages including lower voltage stress, higher efficiency, lower EMI, better waveform and improved THD. This paper presents the development of Altium FPGA as a control circuit for generation of the digital pulse width modulation (DPWM) signal for the single-phase cascaded H-bridge multilevel inverter. The FPGA chip is chosen for the hardware implementation due to its ability to produce accurate results at a high computational speed. Counter based digital pulse width modulation (DPWM) for increased resolution without unnecessarily increasing the clock frequency is used. In addition to Altium Nanoboard FPGA, Xilinx System Generator/MATLAB software has been used for simulation and verification of the proposed circuit before implementation. The simulation and experimental results are in close agreement.

A generalizable, tunable microfluidic platform for delivering fast temporally varying chemical signals to probe single-cell response dynamics.

Understanding how biological systems transduce dynamic, soluble chemical cues into physiological processes requires robust experimental tools for generating diverse temporal chemical patterns. The advent of microfluidics has seen the development of platforms for rapid fluid exchange allowing ease of changes in the cellular microenvironment and precise cell handling. Rapid exchange is important for exposing systems to temporally varying signals. However, direct coupling of macroscale fluid flow with microstructures is potentially problematic due to the high shear stresses that inevitably add confounding mechanical perturbation effects to the biological system of interest. Here, we have devised a method of translating fast and precise macroscale flows to microscale flows using a monolithically integrated perforated membrane. We integrated a high-density cell trap array for nonadherent cells that are challenging to handle under flow conditions with a soluble chemical signal generator module. The platform enables fast and repeatable switching of stimulus and buffer at low shear stresses for quantitative live, single-cell fluorescent studies. This modular design allows facile integration of any cell-handling chip design with any chemical delivery module. We demonstrate the utility of this device by characterizing heterogeneity of oscillatory response for cells exposed to alternating Ca2+ waveforms at various periodicities. This platform enables the analysis of cell responses to chemical perturbations at a single-cell resolution that is necessary in understanding signal transduction pathways.

60 GHz Radio Over Fiber System Based on Gain-Switched Laser

A radio over fiber (RoF) transmission system based on a gain-switched laser as an optical comb source is proposed and demonstrated. 12.5 Gb/s 16 quadrature amplitude modulation (16 QAM) signal generation and transmission over 25 km standard single-mode fiber is experimentally demonstrated using a 60 GHz carrier. The phase noise of the 60 GHz signal resulting from the beating of two partially phase uncorrelated optical tones is theoretically studied and experimentally investigated. Phase noise comparison with different linewidth comb sources is implemented in the proposed RoF system, and the performance of the various systems with different levels of phase noise is presented.

A current-/voltage-controlled four-slope operation square-/triangular-wave generator and a dual-mode pulse width modulation signal generator employing current-feedback operational amplifiers

This paper presents a current-feedback operational amplifier (CFOA)-based current-/voltage-controlled four-slope operation square-/triangular-wave generator. The proposed circuit can adjust the duty cycle of the output waveforms in a current- or voltage-controlled manner, and an external resistor is used to independently control its oscillation frequency. In addition, the DC level of the triangular wave can be adjusted by tuning an input voltage source. This paper also presents a CFOA-based dual-mode pulse width modulation (PWM) signal generator derived from the proposed square-/triangular-wave generator. The literature review in this paper includes previous designs, circuit operations, and the non-ideal effects and design considerations of the proposed circuits. Prototype circuits built with commercially available CFOA integrated circuits (ICs) (AD844ANs) and discrete passive components were used to execute experimental tests to verify the feasibility of the proposed circuits. The experimental results of this study are in agreement with the theoretical analysis.

A Frequency Synchronization Method for a Self-Oscillating PWM Signal Generator

This brief proposes a frequency synchronization method for a full-digital self-oscillating pulsewidth modulation (PWM) signal generator. The self-oscillating PWM signal generator (PSG) generates a variable switching frequency, which results in poor drive performance for a three-phase power inverter or converter. The proposed frequency synchronization method utilizes an additional carrier signal, such as a triangular wave, to fix the switching frequency of a self-oscillating PSG. The switching frequency is synchronized by the triangular wave. As a test case, a switching frequency of 312.5 kHz is used for a performance evaluation of the proposed PSG with a sampling frequency of 12.5 MHz. A first-order noise-shaped output has been obtained. A high-precision PWM signal with low distortion and high resolution of the effective duty cycle has been achieved within the bandwidth. The proposed synchronized self-oscillating PSG is implemented in a three-phase brushless dc motor driver system to confirm the three-phase synchronization performance. Undesirable ripple current from asynchronous operation was not observed. The switching frequencies were synchronized among the three phases.

The Development of Virtual Experiment Platform for Signal Analysis and Processing Based on LabVIEW

A virtual experiment platform for signal analysis and processing based on LabVIEW is developed. Combined with basic principle and method of signal analysis and processing closely six extensible and workable virtual experiment modules are designed. These modules include signal generator, time domain and frequency domain analysis module, band-pass filter, modem, power-spectrum analysis and boundary checkout of sine signal. A simulation and analysis module of shaft orbit is developed on that basis. In the module some shaft orbit shapes corresponding to typical failures of rotors can be simulated, and the amplitude and frequency spectrum of radial displacement of rotor can be analyzed in real time.

Design and Analysis of System for Radar Reconnaissance Based on UML

The design of the software in the training system of reconnaissance radar analysis, which is object-oriented, fully makes use of the development thought of UML. It makes clear the requirements of system function, constructs the use case digrams of the system and the relevant class diagrams. Using the tool of UML dynamic modeling, it respectively describes the scene generator module, radar signal generator module, reconnaissance radar analysis training module of the target system in detail. The users interface and the data base structure of the system are designed in great detail and all the subsystem in target system are designed and developed.

Measurement of Amplifier Open-Loop Amplitude Frequency Characteristics Based on Virtual Instrument

In the electronic measurement field, how to measure the open-loop amplitude frequency characteristics of the amplifier automatically is a question to be overcame. And now , the system ,which under the integrated development environment that the virtual instrument software LabVIEW provides, to measure the open-loop amplitude frequency characteristics of the amplifier is developed by combining the modern electronic measurement technology and computer data processing technology. The virtual signal generator which is based on the data acquisition card, signal acquisition, correlation analysis, frequency response analysis, etc is included in the system. This design mainly includes the hardware circuit and the software program. The hardware circuit consists of the low noise preamplifier, measured operational amplifier, data acquisition card, power supply, computer, etc. Modular design is adopted in the software part, which includes the design of soft panel, signal generation, collection and analysis module. The advantages of the virtual instrument, such as the digital signal processing, waveform data automatic storage, graphical programming, are fully used in the modern electronic measurement. Simple structure, low cost, high level of test automation are its characteristics.

Graphene mechanical oscillators with tunable frequency

Oscillators, which produce continuous periodic signals from direct current power, are central to modern communications systems, with versatile applications including timing references and frequency modulators. However, conventional oscillators typically consist of macroscopic mechanical resonators such as quartz crystals, which require excessive off-chip space. Here, we report oscillators built on micrometre-size, atomically thin graphene nanomechanical resonators, whose frequencies can be electrostatically tuned by as much as 14%. Self-sustaining mechanical motion is generated and transduced at room temperature in these oscillators using simple electrical circuitry. The prototype graphene voltage-controlled oscillators exhibit frequency stability and a modulation bandwidth sufficient for the modulation of radiofrequency carrier signals. As a demonstration, we use a graphene oscillator as the active element for frequency-modulated signal generation and achieve efficient audio signal transmission.

Design of a Self-Oscillating PWM Signal Generator With a Double Integration Loop

A novel digital self-oscillating pulse width modulation (PWM) signal generator with a hysteresis comparator is proposed in this study. The proposed generator, referred to as a “2nd-order PWM signal generator” in this paper, utilizes a double integration loop based upon the concept of delta-sigma modulation for precise conversion. A simple 2nd-order PWM signal generator was initially investigated, but it was found to exhibit impractical behavior: the period of the PWM output signal increased slowly with time. An analysis of the limit cycle state of this simple generator using describing function theory shows that the amplitude of the limit cycle is extremely large. Proportional integral (PI) compensation is therefore used to adjust the limit cycle state by varying the proportional gain and the coefficient of the integral. The use of PI compensation suppresses the amplitude of the limit cycle, thus making the 2nd-order PWM signal generator practical. An analysis of this modified generator reveals that the period of the PWM signal can be controlled by the hysteresis width of the comparator and by the proportional gain. As a test case, a switching frequency of 300 kHz is used for the performance evaluation of the proposed PWM signal generator with a sampling frequency of 12.5 MHz. A noise-shaped output is obtained, and a high-precision, ultra-low-distortion PWM signal with a high effective duty cycle resolution is achieved.

Design of Common Modulation Signal Generator Based on Single-Chip Microcomputer

The common modulation signal generator is mainly composed of STC12C5A60S2 SCM (single-chip microcomputer), DAC0832 chip and their peripheral circuits. Controlled by the SCM, the required analog current is produced by DAC0832, then the current is converted a-5V~5V voltage by the amplifier OP07. Through the control of the switches, the triangle, square, sine and pulse waves can be outputted from generator. Among which, the amplitude of triangle and square and sine waves can be adjusted. The width of square wave and the pulse can be adjusted. Many modulation cases can be showed on the LCD screen. It is proved that the design on the generator is reasonable, the generator performance is stable and reliable, its structure is simple, and its function is high versatility. Admittedly, the designing on modulation signal generator accords with requirement.

SWITCHING POWER AMPLIFIER AND METHOD OF CONTROLLING THE SAME

A switching power amplifier having a pulse width modulation (PWM) signal generation unit that converts an input audio signal into a PWM signal with a predetermined carrier frequency, a correction unit that corrects the difference between an audio signal included in the PWM signal and a negative feedback output audio signal to generate a corrected PWM signal, a low pass filter that removes a high-frequency component from the corrected PWM signal, a frequency modulation unit that modulates the corrected PWM signal so that the corrected PWM signal has a switching frequency different from the carrier frequency of the input PWM signal to generate a modulated PWM signal, and a power amplification unit that amplifies a power of the modulated PWM signal.

A Design Based on Bioimpedance Spectroscopy Method in Human Abdominal Adipose Measurement System

This article describes a measurement of human abdominal fat device designed based on BIS (bioimpedance spectroscopy), the device adopts four electrodes multi-frequency bioelectrical impedance measurement system, including the programmable signal generator module and the amplitude and phase detection module. Program controlled signal generator module can generate the high output impedance of the constant current source in the eight frequency points constant current source between 5KHz and1MHz; amplitude phase detecting module can detect the human body electrical impedance real part and imaginary part information. Therefore, the device can be accurate measurement of human abdominal impedance information in the whole frequency range. Meanwhile, according to the selected electrode fixed position and the appropriate measurement scheme, can calculate the corresponding depth of abdominal fat content.

Design of Parallel Electrical Resistance Tomography System for Measuring Multiphase Flow

ERT (electrical resistance tomography) is effective method for visualization of multiphase flows, offering some advantages of rapid response and low cost, so as to explore the transient hydrodynamics. Aiming at this target, a fully programmable and reconfigurable FPGA (field programmable gate array)-based Compact PCI (peripheral component interconnect) bus linked sixteen-channel ERT system has been presented. The data acquisition system is carefully designed with function modules of signal generator module; Compact PCI transmission module and data processing module (including data sampling, filtering and demodulating). The processing module incorporates a powerful FPGA with Compact PCI bus for communication, and the measurement process management is conducted in FPGA. Image reconstruction algorithms with different speed and accuracy are also coded for this system. The system has been demonstrated in real time (1400 frames per second for 50 kHz excitation) with signal-noise-ratio above 62 dB and repeatability error below 0.7%. Static experiments have been conducted and the images manifested good resolution relative to the actual object distribution. The parallel ERT system has provided alternative experimental platform for the multiphase flow measurements by the dynamic experiments in terms of concentration and velocity.

Realization of the Detecting Method for Aircraft Digital Image Transmission System Based on Multi-Processor

The technologies of image block, pyramid and multi-threading were used in this program to design the high-speed image generation display module and the processes of image data scheduling and mapping and solve the problems of large-capacity image data modeling and high-speed displaying. The technology of direct digital frequency synthesis (DDS) was used to design the Doppler shifting signal generation module and the multi-processor parallel system architecture, which can analog the Doppler frequency shifting of the data communication signals and solve the problem of the authenticity of communication signals during the simulated flight.