High Frequency Output Research Articles

Design of CMOS-based low-power high-frequency differential ring VCO

ABSTRACTAn improved design of four-stage CMOS differential ring voltage-controlled oscillator (VCO) with high-output frequency, low phase noise, and low power consumption is proposed in this paper. A new differential delay cell has been used for differential ring VCO which utilises dual-delay-path topology to attain both high-output frequency and low phase noise. The simulation results have been obtained in TSMC 0.18-µm CMOS process with a supply voltage (Vdd) 1.8 V. The proposed design of VCO exhibits an output oscillation frequency range from 1.619 to 3.712 GHz. The power consumption for this frequency range varies from 4.628 to 10.545 mW with control voltage variation from 0.1 to 1.0 V. The proposed design occupies compact layout area of 0.207 mm2 and achieves – 89 dBc/Hz phase noise at 1 MHz offset from 3.712-GHz carrier frequency. Improved performance for this design has been achieved in terms of output oscillation frequency, phase noise, and power consumption.

UHF Band High-Speed CP-2FSK Modulator’s Design

Aimed at requirements of signal transmission rate in the UAV data link, the UHF band CP-2FSK modulator design method based on Direct Digital Synthesis technology is given, and hardware circuit implementation of the UHF band CP-2FSK functions, get UHF band modulation signal CP-2FSK of code rate up to 67.2 Mbps baseband signal. The transmission experiments of the image signal in UAV data link had been achieved. It suggested the modulator has many advantages such as low power consumption, high output frequency, high transmission rate, occupied channel bandwidth. It meets the design requirements of the UAV data link telemetry data transmission and achieve high-speed transmission UAV telemetry data downlink.

Design of a System to Generate a Four Quadrant Signal at High-Frequency

AbstractIn order to research biological cells, a well-established physical method can be used, that is electrorotation. To achieve electrorotation system, a signal oscillator or a signal generator is always needed. The signal generator is used for generating signals with phase shift and transfers it to the electro chamber. The frequency range of the output signal is generally between 20 Hz to 100 MHz for the signal generator, but for high frequency range, like 100 MHz to 1 GHz, the signal generator is hard to control and the linear properties for the output signal is not good enough to do the electrorotation. So design a signal generator to generate a signal with high frequency range is indispensable, and this is good for researching the biological cells in high frequency environment. The project finished by doing research for some available signal generators, like Phase-Locked Loop (PLL) and Direct Digital Synthesis (DDS), and the final system with high frequency output signal has been designed after the...

FPGA-Based Space Vector Pulse Width Modulated Single-Phase to Three-Phase Converter

ABSTRACTConversion of single-phase power supply into three-phase power supply has always been a commercial approach. There is an ever-increasing demand of high-speed electrical machines for a wider range of applications. This paper presents a single-phase to three-phase converter which can generate high frequency output voltage in a single stage to drive high-speed induction motor. A modified space vector pulse width modulation (PWM) technique has been implemented to reduce the total harmonic distortion factor in the output of the converter. In order to generate approximately sinusoidal three-phase output, genetic algorithm has been used as a mathematical tool to estimate the switching angles of different devices in the converter. Detailed design and simulation analysis is presented for single-phase to three-phase converter-fed induction motor drive. A laboratory prototype of the proposed converter is developed through Xilinx field programmable gate array. Test results are presented to validate the proposed design and simulated results of the system.

Multiple output second-generation current conveyor utilizing high frequency output stage

Multiple output second-generation current conveyor utilizing high frequency output stage

Real-Time Motion Tracking for Mobile Augmented/Virtual Reality Using Adaptive Visual-Inertial Fusion.

In mobile augmented/virtual reality (AR/VR), real-time 6-Degree of Freedom (DoF) motion tracking is essential for the registration between virtual scenes and the real world. However, due to the limited computational capacity of mobile terminals today, the latency between consecutive arriving poses would damage the user experience in mobile AR/VR. Thus, a visual-inertial based real-time motion tracking for mobile AR/VR is proposed in this paper. By means of high frequency and passive outputs from the inertial sensor, the real-time performance of arriving poses for mobile AR/VR is achieved. In addition, to alleviate the jitter phenomenon during the visual-inertial fusion, an adaptive filter framework is established to cope with different motion situations automatically, enabling the real-time 6-DoF motion tracking by balancing the jitter and latency. Besides, the robustness of the traditional visual-only based motion tracking is enhanced, giving rise to a better mobile AR/VR performance when motion blur is encountered. Finally, experiments are carried out to demonstrate the proposed method, and the results show that this work is capable of providing a smooth and robust 6-DoF motion tracking for mobile AR/VR in real-time.

Research and Simulation of Two-Phase Interleaving Boost Converter

本文介绍了交错并联技术的基本原理及其优点，详细分析两相交错并联Boost变换器基本原理，分别采用PI控制和数字电流滞环控制方法，简单叙述了两种控制方法的原理并进行优缺点的分析与对比。使用MATLAB仿真，结果显示采用交错并联技术能在很大程度上减小流过开关管的电流，降低开关损耗和输出电压、输出电流纹波；相对于PI控制，采用数字电流滞环的控制方法使得整个电路的性能得到提升。 This paper introduces the basic principle and unique advantages of interleaving technology, and analyzes the efficacy of the two-phase interleaved boost converter in detail. In the control part of the circuit, a PI control strategy and digital hysteresis current control strategy are respectively adopted for the sake of comparison. Via MATLAB simulation, interleaving technology is shown to possess a number of important advantages compared to other methods, such as high frequency output voltage ripple with lower switching frequency, reducing current flowing through the switch tube, reducing switching loss, decreasing output voltage ripple, and output current ripple. Compared to the PI control method, the digital hysteresis current control method makes the performance of whole circuit is improved.

Magnetostrictive stress induced frequency shift in resonator for magnetic field sensor

A static/quasi-static magnetic field sensor is developed by using a double ended trip-beam tuning fork (TBTF), a TbxDy1-xFe2-y plate and several piezoelectric Pb(Zr1−xTix)O3 (PZT) plates. The TBTF is boned horizontally across two ceramic supports which are fixed on the ends of the TbxDy1-xFe2-y plate. The magnetostrictive stress induces an axial force in the TBTF, which causes the resonance frequency of the TBTF to increase. The theoretical analysis shows that the magnetostrictive stress increases approximately linearly with the increase of the external DC field, and so does the resonance frequency shift of the TBTF. The magnetostrictive stress can get to 32.65MPa at the field of 1000Oe, and the total frequency shift respectively achieves 2.97% and 16.67% under the assumption of 10% and 60% transmission efficiencies (as the sectional area of the magnetostrictive plate being 6mm×1mm). A Be-bronze TBTF based sensor was fabricated, and the frequency shift of 2.1% was obtained by applying a DC magnetic field in the range of 0–1000Oe. The magneto-mechanical damping in the magnetostrictive plate has no influence on the quality factor of the TBTF which is found to be relatively constant after an initial increase. The results show the great potential to realize a high sensitivity magnetic sensor featuring high quality factor and digital frequency output.

Surface circulation at the Strait of Gibraltar: A combined HF radar and high resolution model study

AbstractObservations from a high frequency radar system and outputs from a high resolution operational ocean model working at the Strait of Gibraltar have been analyzed and compared during the period February 2013 to September 2014 in order to evaluate their capability to resolve the surface circulation of the region. The description of the mean circulation patterns has been statistically assessed, showing good agreement, particularly in the central region of the strait corresponding with the Atlantic Jet (AJ) stream, although some short scale features are not reproduced by the model. In the frequency domain very high concordance is observed. Tidal maps of diurnal and semidiurnal constituents are in good agreement with previous observations. The analysis of the model and radar response to the wind forcing reveals that the low resolution of the model wind‐forcing field and its deeper superficial level smoothes the wind effect on the simulated currents. The first three EOF modes account for the 86% of model and radar variances. The coincidence between the observed and simulated patterns is very significant for the first two modes, which account for the mean velocity field and the latitudinal shifting of the AJ consequence of the flow‐topography interaction. The third mode captures the wind‐induced circulation, and greater discrepancies are found in this case. Results underline the complementary character of both systems: radar observations improve the model description, resolving short scale processes, while the model completes the radar information when the time or spatial coverage is poorer.

Analog Multiplier Based Single Phase Power Measurement

Present paper proposes a power measurement technique of a single phase electrical load. The proposed method is a low cost power measurement technique. The load which is taken into consideration is either resistive load such as bulb or inductive load like single phase induction motor. This method is based on a low cost analogue IC (AD633) which does the analogue multiplication of the two input signals. In fact, AD633 is well suited for applications such as power measurement, modulation and demodulation, automatic gain control, voltage-controlled amplifiers, and frequency doublers. In present work AD633 is employed for power measurement. The AD633 output voltage give the multiplication of corresponding current and voltage signals of the load and produces pulsating signal/voltage at the double of the supply frequency. The higher frequency output of AD633 is attenuated by a low pass filer of an appropriate cut-off frequency (90 Hz). The corresponding DC component of the multiplier IC output obtained at the output of the active RC low- pass filter is found to be proportional to the average load power consumed. The output of RC low pass filter was plotted against different values of load using MATLAB code. The linearity of these plots was checked through the linear curve fit and the original plots for the validation purposes

The Design of Signal Generator Based on FPGA High Resolution

In view of the digital geophone self-test system application demand for a variety of high quality waveform signal. This paper introduces a kind of design method of direct digital synthesis waveform signal generator based on FPGA. It mainly discusses the principle of the method of frequency synthesis technology, design thinking and implementation method. And using the design method of pipeline structure to improve circuit structure of 48 bits phase accumulator, so as to improve the running speed, and further increase the resolution of frequency synthesis. The test shows that the signal generator can produce sine wave, square wave, sawtooth wave, triangle wave. The frequency resolution can reach 0.18μHz. The highest output frequency is up to 20MHz, and frequency switch time is 20ns.

Design and Implementation of 2by3 Prescalerusing Different Logic in CMOS 45nm Technology

Frequency division is one of the important applications of flip-flops. A wide-band frequency synthesizer implemented by phase-locked loop (PLL) uses prescaler (also called N/N+1 counter) as fundamental block. In PLL high frequency output of VCO is coupled directly to the prescaler directly. As process technology is reducing, channel length and supply voltage is decreasing rapidly. Therefore prescaler has to work at high frequency as well as low operating voltage. Using pass transistor or CMOS Technology are the incorporation of additional logic gates between the flip-flops to achieve the two different division ratios, the speed of the prescaler is affected by creating another propagation delay and the increases the switching power.

Design of Excitation Source for Ultrasonic Guided Waves Based on DDS Technology

According to the characteristics of ultrasonic guided wave inspection, An exciting power, used for exciting ultrasonic guided waves in pipeline is designed based on DDS and FPGA. The excitation source consists of FPGA, D/A conversion circuit, a low-pass filter circuit and power amplifier circuit. Constructing DDS based on FPGA as the controller and signal generator. Filter circuit and power amplifier circuit are designed in this paper. The experiment results show that the excitation source can have high voltage and high frequency output capability, and can generate desired signal type with a good accuracy to fit the requirements in practice. It can be conveniently used for pipeline ultrasonic guided wave detection.

Field‐programmable gate array‐based linear–non‐linear control with high‐resolution digital pulse width modulator and high‐speed embedded analogue‐to‐digital converter for multi‐phase voltage regulator modules

Power converters for applications with high switching frequency and tight output voltage regulation such as voltage regulator modules (VRM) for microprocessors power supplies require fast dynamic response to meet the specifications. An existing control technique known as linear-non-linear (LnL) control strategy allows improving the transient converter response by means of an easy rule for the saturation of the duty cycle. The use of a digital implementation can optimise the transient response of the multi-phase VRM with LnL. However, digital control leads to other problems derived from time discretisation and finite word length effects. The limited resolution and the sampling delay are critical issues for digital control implementation of multi-phase VRM with LnL control. As a result, a high-resolution digital pulse width modulator (DPWM) and high-speed analogue-to-digital (A/D) converter are required to obtain proper performance of the converter. This study is focused on the digital implementation of the well-known LnL control in a multi-phase VRM taking advantage of low-cost field-programmable gate array resources. A detailed description of the digital implementation of the main converter control blocks, which are the A/D converter, the compensator and the DPWM, is provided in the paper.

PROBABILISTIC PROPERTIES AND EVALUATION OF DESCRIPTIONS OF INITIAL SIGNAL OF NONLINEAR SYSTEM AT ACTION OF PERIODIC WHITE NOISE

We prove the theorem of moment functions of higher frequency output process chasoinvariantnoyi nonlinear system, provided that the input is valid on its periodic white noise. Grounded statistical methods for evaluation of periodic functions torque output process nonlinear system.

The diurnal cycle of marine cloud feedback in climate models

We examine the diurnal cycle of marine cloud feedback using high frequency outputs in CFMIP-2 idealised uniform +4 K SST perturbation experiments from seven CMIP5 models. Most of the inter-model spread in the diurnal mean marine shortwave cloud feedback can be explained by low cloud responses, although these do not explain the model responses at the neutral/weakly negative end of the feedback range, where changes in mid and high level cloud properties are more important. All of the models show reductions in marine low cloud fraction in the warmer climate, and these are in almost all cases largest in the mornings when more cloud is present in the control simulations. This results in shortwave cloud feedbacks being slightly stronger and having the largest inter-model spread at this time of day. The diurnal amplitudes of the responses of marine cloud properties to the warming climate are however small compared to the inter-model differences in their diurnally meaned responses. This indicates that the diurnal cycle of cloud feedback is not strongly relevant to understanding inter-model spread in overall cloud feedback and climate sensitivity. A number of unusual behaviours in individual models are highlighted for future investigation.

A portable high-frequency digitally controlled oscillator (DCO)

A novel digitally-controlled oscillator (DCO) is reported. Utilizing a new capacitive load, the new DCO is capable of producing much higher output frequencies than existing DCOs. All other components are fully digital and modular, allowing portability to any CMOS process and customization for different applications. At the heart of the DCO is a digital ring oscillator (DRO) that utilizes the new shunt-capacitive loads. Unprecedented higher frequencies are obtained through a novel idea of electrically removing the effect of un-enabled loads. Simple design conditions for achieving proper operation of the DRO are provided and verified through simulations with several technologies. Spice simulations verified the correct and superior operation of the DCO even with device mismatch. A custom layout of the DRO was generated using LFoundry's 150nm technology. The total DRO area was found to be 418µm2. Comparison with other DCOs and VCO shows that the new DCO outperforms conventional DCOs in all aspects; maximum attainable frequency, power efficiency and required number of control bits to achieve a certain resolution.

Optical flow sensor through near-field grating diffraction

A novel optical flow-meter has been developed, especially designed for very-high flow speed. The system is a variant of laser Doppler velocimeter (LDV), realized by means of an optical phase-grating. Standard LDV generates a fringes pattern by means of two laser beams, intersecting at an angle α. For fast flow rates, the fringe period has to be very long, in order to avoid too high output frequencies, therefore a very low angle α is required. For the realization of such pattern we propose a different approach, employing an optical grating, working in the near-field range. This technique has been demonstrated by measuring the flow-speed distribution in a water-jet machine.

Design of the Broadband Standard Signal Generator for Laser Locating System of the Mine Hoisting Container

As the key junction between the ground and underground, hoisting systems as well as mines themselves are of vital importance to coalmine production. Laser ranging method is studied as a new solution of getting the real-time position directly. Furthermore, multi-scale phase based laser ranging principles are utilized in the system. The paper is aimed to conduct research into the problems existing in standard signal generating while using laser to locating the hoisting container, and to design standard sine generator circuits with DDS technology and DDS devices AD9850 to generate multiple frequency standard signals. In view of the serious noise disturbance in high frequency output, 4-order Chebyshev low-pass filter is designed, by using the integrated analog filters LT 6600-15, to filter the sine signals from AD9850 and to effectively weaken the noise disturbance. The established practical circuits are tested, obtaining trillion level high frequency and low frequency sine signals and fulfilling the requirements for the location system of hoisting containers.

Beatless Synchronous PWM Control for High-Frequency Single-Pulse Operation in a Matrix Converter

In this paper, a beatless control that enables unity input power factor for the single-pulse operation in the matrix converter is proposed. The proposed method controls the output voltage to synchronize with the output current in terms of voltage–time product during the high output frequency operation. Following the proposed synchronous control method, the beat current is suppressed by approximately 1% at output frequency 1432 Hz. The experimental results also demonstrate that the input current waveform achieves sinusoidal waveform with unity power factor. In addition, the voltage transfer ratio of the matrix converter is improved from 0.866 to 0.955 in the high output frequency region. The maximum efficiency 96.4% is achieved at a 1.34-kW RL load.