Equivalent Time Sampling Technique Research Articles

AC Power Cycling Test Setup and Condition Monitoring Tools for SiC-Based Traction Inverters

AC power cycling tests allow the most realistic reliability assessment by applying close to real stress to the device or module under test to meet functional safety standards, which is highly critical for traction applications. This paper presents a comprehensive guideline and shares critical know-how to develop a 120 KVA AC power cycling test setup for high-power Silicon Carbide (SiC) modules. As of today, traction applications can not generate an early warning signal for drivers to replace critical components on time. For this purpose, the suitable precursors for all dominant failure mechanisms are discussed, and the corresponding condition monitoring tools are proposed to monitor the device aging on power converters. These condition monitoring tools are integrated into the built-in desaturation protection circuit of the electric vehicle (EV) gate driver for low-cost, practical implementation. The on-resistance of all twelve switches is monitored online as a temperature-sensitive electrical parameter (TSEP) to measure the junction temperature of the devices. To avoid heavy processing load in the microcontroller, the out-of-order equivalent time sampling technique is developed for data sampling, which leads to a measurement error of less than 1.5%. In addition, the design considerations regarding common mode noise and aging effect on DESAT protection are investigated, and experimental findings are presented.

5 Gs/s 등가 시간 샘플링을 통한 K-Band UWB 레이다 송수신기

In this paper, a K-band complementary metal-oxide-semiconductor (CMOS) ultra-wide-band (UWB) radar is presented. Using an equivalent time sampling technique with a delay-locked loop (DLL), virtual 5 Gs/s high-speed sampling is implemented without using a high-speed analog–digital converter. The receiver comprises a low-noise amplifier, radiofrequency variable amplifier, mixer, and baseband analog, whereas the transmitter comprises switching and driver amplifiers. For the UWB signal, a voltage-controlled oscillator-based impulse generator provides a periodic pulse signal using a switching amplifier controlled by a DLL clock. The proposed UWB radar SoC is fabricated using a 65 nm CMOS wafer, and the measured conversion gain and noise figure of the radar receiver are 79 dB and 7.4 dB, respectively, at 24 GHz. Consequently, we confirm that the measurement of the 11.3 m standard sphere is feasible.

Metallic Ratio Equivalent-Time Sampling and Application to TDC Linearity Calibration

In LSI testing, equivalent time sampling techniques are frequently used because the input signals to the device under test and the sampling clock are controllable; when repetitive input signals are applied to the analog device under test, its output signals can be also repetitive. In this paper, we investigate an efficient waveform acquisition method with equivalent-sampling using the metallic ratio of the sampling frequency and the input frequency, which is expected to be used for on-line, short-time and simple analog/RF/mixed-signal IC testing. We reveal that metallic sampling technique can be a powerful tool for the TDC linearity calibration with the histogram method.

E-DTDOA Based Localization for Wireless Sensor Networks With Clock Drift Compensation

A high time resolution localization scheme, using ultra-wide band ranging signal with bandwidth of 2GHz, is proposed for a fully asynchronous wireless sensor network (WSN). The proposed scheme is specifically useful for sensor nodes which are designed to operate at very low ADC sampling rate, in the order of 2–3 MHz, but still achieves the sampling resolution in the order of sub-nanoseconds. To achieve low sampling rate, equivalent time sampling (ETS) technique is used at the sensor nodes. Reconstructed signal obtained by ETS technique, that require periodic transmission of the same signal repetitively, is severely affected by the variation in transmitter and receiver clock drift as against the real time sampling where the variations are due to receiver node clock drift only. Thus, it requires a protocol to precisely estimate the transmitter and receiver clock parameters. A scheme, which uses a novel mathematical equivalent time of arrival (E-TOA) model for ETS based system, for clock drift estimation is presented. Based on clock drift estimation parameters, receiver nodes are tuned to the same frequency. E-TOA measurements are further used to propose an equivalent differential time difference of arrival (E-DTDOA) based ranging algorithm, which relaxed the time synchronization requirement between the wireless nodes, and still achieving high time resolution. The E-DTDOA range measurements are subsequently used to obtain precise localization of the target node/s. The feasibility of the algorithm proposed is demonstrated experimentally using in house designed wireless sensor nodes.

초고속 이동체 탐지에 적합한 초광대역 CMOS RFIC 기반 레이다 시스템

This paper presents CMOS UWB RFIC based radar system for high speed target detection. The system can achieve resolution of 15 cm and detection range of 15 m. For developed system, single chip CMOS UWB IC is implemented. To reduce the measuring and processing time, envelope detection and equivalent time sampling technique are used. Measurement results show that the bandwidth and center frequency of UWB pulse can be adjusted in the range of 0.5 GHz∼1.0 GHz, 3.5 GHz∼4.5 GHz, respectively. Signal processing time including scan time over 15 m distance is about 150 μsec.

Graphene metamaterial modulator for free-space thermal radiation.

We proposed and demonstrated a new metamaterial architecture capable of high speed modulation of free-space space thermal infrared radiation using graphene. Our design completely eliminates channel resistance, thereby maximizing the electrostatic modulation speed, while at the same time effectively modulating infrared radiation. Experiment results verify that our device with area of 100 × 120 µm2 can achieve a modulation speed as high as 2.6 GHz. We further highlight the utility of our graphene metamaterial modulator by reconstructing a fast infrared signal using an equivalent time sampling technique. The graphene metamaterial modulator demonstrated here is not only limited to the thermal infrared, but may be scaled to longer infrared and terahertz wavelengths. Our work provides a path forward for realization of frequency selective and all-electronic high speed devices for infrared applications.

Modeling and Jitter Improvement of SRD-Based Ultra-Wideband Pulse Generator

Step recovery diode (SRD)-based ultra-wide band (UWB) pulse generators (PGs) suffer from jitter caused by AM-to-PM conversion, SRD shot noise, and clock jitter. These noise sources significantly impact the accuracy of UWB systems if very high precision ranging/positioning is required. Jitter behavior caused by the transmitter and receiver is mostly detrimental in the equivalent time-sampling receiver. Thus, a mathematical model for simulation of the jitter and amplitude variation effect in the equivalent time-sampling technique has been developed and used in SystemVue simulations. A criterion as an estimate of system accuracy is defined as signal-to-distortion ratio (SDR) and used. Similarly, a model for AM and PM noise analysis for an SRD-based UWB PG is developed that was validated experimentally. In addition, SRD shot-noise contribution on output jitter was evaluated using the proposed model. Based on these models, methods to reduce the output jitter of the system have been recommended. Simulation showed that clock jitter and SRD shot noise led to pronounced output jitter, with shot noise the primary cause. For a typical SRD-based UWB PG, an output jitter of around 3 ps has been achieved using improvement techniques based on the proposed method, compared to a 15-ps jitter before improvement. These measured results are in good agreement with our predictions.

Towards Low Cost, High Speed Data Sampling Module for Multifunctional Real-Time UWB Radar

There is a need for the development of a low cost, low jitter, fast processing hardware for various ultrawideband (UWB) radar applications, such as dynamic real-time imaging and micro-Doppler human motion detection with high range resolution. Achieving such high range resolution is typically limited by the availability of low cost gigahertz sampling speed electronics. In order to achieve dynamic real-time imaging, a fast refresh rate and high-speed processing are essential, but they are typically very expensive and difficult to obtain. To circumvent the need for these very expensive processors, an equivalent time sampling method has been successfully applied to implement a compact data acquisition module with a low cost solution. The developed integrated compact module supports dual sampling channels with a maximal 100 giga-samples per second (GSPS) equivalent time sampling rate and relatively low jitter. The equivalent time sampling technique achieves a relatively high effective capture rate, however, this is at a cost of complicated timing control logic and sampled data reconstruction. The developed module includes a novel, robust, efficient, low-jitter data preprocessing scheme implemented in field-programmable gate arrays (FPGAs), and a faster back projection method based on look-up table for real-time 2D imaging. In the work presented here, the design details of the newly developed system as well as its performance are discussed. Various examples of utilizing the developed radar for real-time high resolution target imaging and micro-Doppler detection are also presented.

125 mW 102.4 GS/s Ultra-High-Speed Sampling Circuit for Complementary Metal–Oxide–Semiconductor Breast Cancer Detection System

For application to an impulse-radio ultra-wideband (IR-UWB) portable breast cancer detection system, a 102.4 GS/s sampling circuit is developed. The high sampling rate is realized by an equivalent-time sampling technique and a low-power multi-clock generation circuit using a phase interpolator. The phase interpolator achieved a minimum phase resolution 9.8 ps. Using the sampling circuit, a tumor phantom buried by a breast phantom was detected.

32 GS/s ultra-high-speed UWB sampling circuit for portable imaging system

A 32 GS/s ultra-high-speed ultra-wideband (UWB) sampling circuit has been developed by use of a 65 nm CMOS technology. An equivalent time sampling technique was applied using an internal clock generator to achieve its low power consumption and high sampling rate. The generator consists of an eight-stage 2 GHz phase-locked loop, a 16-to-1 multiplexer and a frequency divider. Both a 20 mW low power consumption and a 32 GS/s high sampling rate were achieved. Gaussian monocycle pulse signals with a centre frequency of 450 MHz could be successfully converted to digital codes.

Measurements of hydroxyl concentrations and lifetimes in laminar flames using picosecond time-resolved laser-induced fluorescence

Picosecond time-resolved laser-induced fluorescence (PITLIF) can potentially be used to obtain measurements of minor species concentrations in rapidly fluctuating flames. Previous studies demonstrated this potential for atomic sodium by monitoring the temporal fluorescence signal with both an equivalent-time and a real-time sampling method. In this developmental study, PITLIF is used to determine hydroxyl concentrations in laminar CH(4)-O(2)-N(2) flames by the measurement of both the integrated fluorescence signal and the fluorescence lifetime. The quenching environment can be monitored with real-time sampling, and thus the necessary quenching rate coefficient is obtained in 348 us, which is fast enough for use in many turbulent flows. Fluorescence lifetimes of OH are also measured at different equivalence ratios in laminar flames by the use of the equivalent-time sampling technique. These results compare favorably with predicted lifetimes based on relevant quenching cross sections and calculated species concentrations.

Digital spectra of nonuniformly sampled signals: fundamentals and high-speed waveform digitizers

A digital spectral representation of a nonuniformly sampled signal is derived, and a spectrum analysis of a nonuniformly sampled sinusoid is presented. It is found that the spectrum of a nonuniformly sampled sinusoid comprises uniformly spaced line spectra; in addition, the signal-to-noise ratio is obtained in closed form. The theories are then applied to analyze the harmonic distortion introduced in high-speed waveform digitizers due to time-base errors. Specifically, waveform digitizers are analyzed which utilize interleaving/multiplexing and random equivalent time-sampling techniques and the monolithic A/D converter technology to extend their capabilities. Theoretical results are confirmed by experimental results with a real waveform digitizer.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>