A 5‐GHz energy‐efficient tunable pulse generator for ultra‐wideband applications using a variable attenuator for pulse shaping

A new energy‐efficient tunable pulse generator is presented in this paper using 0.13‐µm CMOS technology for short‐range high‐data‐rate 3.1–10.6 GHz ultra‐wideband applications. A ring oscillator consisting of current‐starved CMOS inverters is quickly switched on and off for the duration of the pulse, and the amplitude envelope is shaped with a variable passive CMOS attenuator. The variable passive attenuator is controlled using an impulse that is created by a low‐power glitch generator (CMOS NOR gate). The glitch generator combines the falling edge of the clock and its delayed inverse, allowing the duration of the impulse to be changed over a wide range (500–900 ps) by varying the delay between the edges. The pulses generated with this technique can provide a sharp frequency roll off with high out‐of‐band rejection to help meet the Federal Communications Commission mask. The entire circuit operates in switched mode with a low average power consumption of less than 3.8 mW at 910 MHz pulse repetition frequency or below 4.2 pJ of energy per pulse. It occupies a total area of 725 × 600 µm² including bonding pads and decoupling capacitors, and the active circuit area is only 360 × 200 µm². Copyright © 2011 John Wiley & Sons, Ltd.     

Breakdown characteristics of oil and paper insulation for a very fast transient voltage

This paper describes the dielectric breakdown characteristics of oil and oil‐impregnated paper for very fast transient (VFT) voltages. Blumlein circuits generate VFT voltages of 60 and 300 ns in a pulse width that simulates disconnecting switching surges in gas‐insulated switch gears. We measured the breakdown voltages of needle‐to‐plane, plane‐to‐plane oil gaps and several pieces of paper between plane electrodes for VFT and lightning impulse voltages. The measured data were formulated in V‐t characteristics and Weibull probability distributions. The inclination n of V‐t characteristics of insulating paper is 150, which is less than n = 13.7 of the plane‐to‐plane oil gap in the VFT time range. The shape parameters of Weibull distribution obtained in this study show that the scattering of breakdown voltages of paper is much less than that of oil. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(4): 16–24, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10043     

RF transmitter using the dual‐pulse position modulation method for low‐power smart micro‐sensing chip

This paper presents a low‐power radio frequency (RF) transmitter using dual‐pulse position modulation (DPPM) for a smart micro‐sensing chip (SMSC) with sensors and large scale integrated circuit (LSI) on the same chip. The DPPM method is presented by a fixed pulse and a variable pulse within the same time frame. The distance between the fixed pulse and the variable pulse describes the amplitude of the input signal. A modulator and a ring oscillator were designed for the RF transmitter using the DPPM method. In the modulator, the pulse width modulation (PWM) signal is generated by the intersective method, and narrow pulses are extracted at the rising and falling positions of the generated PWM signal. The designed oscillator has the function of an oscillation controller. The RF transmitter was fabricated with sensors for an SMSC by complementary metal–oxide–semiconductor (CMOS) technology. The power consumption of the fabricated modulator was 4.5 mW. The power consumption of the proposed RF transmitter was measured as 7.0–7.3 mW at an input signal of 0.8–2.5 V. The RF transmitter using the DPPM method was able to reduce the power consumption by a maximum of 50.3% compared to a transmitter using the PWM method, because in the latter the dissipated power was 8.4–14.5 mW at the same input signal. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Application of step‐response test for evaluation of uncertainty of standard measuring system for lightning‐impulse high voltage

In evaluating the uncertainty of the standard measuring system for lightning‐impulse high voltages, which is composed of a standard voltage divider, a digital recorder, and calibrators, step‐response tests of the standard voltage divider may be useful. In this paper, a convolution algorithm is employed to calculate the output impulse voltage waveforms from measured step‐response waveforms. The uncertainties of peak‐value measurement due to the influence of the nominal epoch, uncertainty of the peak‐value measurement due to dispersion of the AC scale factor, and uncertainty of the virtual front‐time measurement due to long‐term stability are evaluated. Furthermore, the error of the virtual front time of the output waveforms is discussed. The front part of the step‐response waveform, t≤ T₃₀%, does not influence the error of the virtual front time. Therefore, for the standard voltage divider, the step‐response parameters, that is, the experimental response time, partial response time, settling time, and overshoot, have almost nothing to do with the error of the virtual front time. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(2): 24–32, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21279     

Development of a laser wavefront sensor for measurement of discharges in air

A laser wavefront sensor of the Shack‐Hartmann type capable of simultaneous measurement at two wavelengths was constructed. The sensor uses a single optical path, and is suited for applications such as high‐voltage discharges in air, in which large insulation distances are necessary. The sensor was used to detect optical path differences due to an impulse discharge in air across a needle–plane electrode gap of gap length 17 mm. Optical path differences were measured at laser wavelengths of 532 and 1064 nm at 1.6 µs after insulation breakdown across the gap. From the difference in optical path differences at the two wavelengths, a line‐integrated electron density distribution in the direction perpendicular to the gap was obtained near the high‐voltage electrode. The distribution had a peak value of 1.4 × 10²⁰m^?2 and a full width at half maximum of 4.4 mm. Because of the coverage of a large observation area including the entire gap, the spatial resolution was 1.4 mm, which was inadequate to obtain the precise form of the electron density distribution. However, the results show the possibility of applying laser wavefront sensing to electron density measurement. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 10–17, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10247     

Test circuit of impulse spark‐over voltage with different rates of rise for gas discharge tubes

The impulse spark‐over voltage of the gas discharge tube (GDT) is strongly related to the rate of rise (RoR) of the voltage. At present, due to the convenience of the test instrument, conventional impulse waveforms, such as 1.2/50 and 10/700 μs, are often adopted to conduct such kind of test for GDT. It has been found that these waveforms are able to generate valid waveforms only with limited RoRs and relatively narrow valid voltage ranges. This paper deals with a simple series RC circuit to test the GDT's impulse spark‐over voltage using a ramp voltage, which is approached by an initial portion of a steeply rising voltage impulse whose normal peak value is several times the breakdown voltage of the GDT. The basic circuit theory is described, and the RoR of the output voltage is correlated with the circuit parameters. Moreover, the series RC circuit in this paper is found to be able to deliver a ramp voltage with more consistent RoR than an RLC circuit. The results in this paper provide some suggestions for the revision of relevant standards (e.g., ITU‐T K.12 and IEC 61643‐311). Circuit parameters for different RoRs ranging from 100 V/μs to 1 kV/ns are also established. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Discharge characteristic investigation on surface discharge initiated by metallic particles attached to gas‐insulated substation insulator

The ultrahigh frequency (UHF) method is used for detecting the three kinds of surface discharges started by metallic particles on the spacer insulators in gas‐insulated switchgear (GIS). Three different designs of the same surface defect are applied to ensure the consistency of the results. The present experiments are made on a 220‐kV GIS, which is close to the actual situations to study the surface discharge characteristic. A measuring system for this purpose consists of an oscilloscope connected to UHF sensors. Partial discharge (PD) data was captured by UHF detection using an oscilloscope and stored as phase‐resolved pulse sequence (PRPS) data. Since PRPS data contain the complete information of the PD, PRPS analysis (PRPSA) pattern and three‐dimensional ϕ − q − n (3D PRPD) pattern can be calculated from the recorded PRPS datasets. The PRPSA data also allows us to obtain the actual test voltage (rms) of every cycle, the number of measuring cycles, and phase information of all PD pulses, together with their peak values, so that a statistical analysis of these data can be discussed. Besides, this paper also focuses on the frequency analysis and time–frequency analysis of the single‐pulse time‐domain signal. It is shown that the characteristic parameters obtained from the PRPS data, frequency spectrum, and time–frequency spectrum have the potential to be used as PD characteristic interpretation and further research on PD pattern identification. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Power‐efficient burst‐mode RF transmitter based on reference‐adaptive multilevel pulse‐width modulation

Burst‐mode operation of power amplifier (PA) based on multilevel pulse‐width modulation (MPWM) has been frequently discussed as a potential solution to achieve higher efficiency in radio frequency (RF) transmitters. In this paper, a novel multilevel PWM modulator is proposed that utilizes adaptive triangular reference waveforms. As compared with conventional MPWM modulators, the proposed architecture provides significant wider design space such that the efficiency of system can be effectively optimized. A general transmitter architecture based on the proposed concept is analyzed in terms of power efficiency. Efficiency optimization procedures are presented according to input magnitude statistics. Based on the proposed modulator, an optimized 2.4‐GHz RF transmitter is designed in a 0.18‐μm complementary metal‐oxide‐semiconductor (CMOS) process. The circuit‐level simulations show that it delivers 25.8‐dBm peak output power with 46.1% peak efficiency. For a 20‐MHz worldwide interoperability for microwave access (WiMAX) signal with 8.5‐dB peak‐to‐average‐power ratio (PAPR), this transmitter achieves 28.8% (average) efficiency at 17.3‐dBm (average) output power with an error vector magnitude (EVM) of 2.97% rms.     

Switched‐capacitor‐voltage‐multiplier boost DC–AC inverter with adaptive stages

A multistage switched‐capacitor‐voltage‐multiplier inverter (SCVMI) is proposed with a variable‐conversion‐ratio phase generator and a sinusoidal pulse‐width‐modulation controller for boost DC–AC conversion and high‐efficiency regulation. Its power unit contains: SCVM booster and H‐bridge. The SCVM booster includes two m_c‐stage switched‐capacitor cells and two n_c‐stage switched‐capacitor cells in the interleaving operation to realize DC–DC boost gain of m_c × n_c at most. Here, the variable‐conversion‐ratio phase generator is suggested and adopted to change the running stage number and topological path for a suitable gain level of m × n (m = 1, 2, ?,m_c, n = 1, 2, ?,n_c) to improve efficiency, especially for the lower AC output. The H‐bridge is employed for DC–AC conversion, where four switches are controlled by sinusoidal pulse‐width‐modulation not only for full‐wave output but also for output regulation as well as robustness to source/loading variation. Some theoretical analysis and design include: SCVMI model, steady‐state/dynamic analysis, conversion ratio, power efficiency, stability, capacitance selection, output filter, and control design. Finally, the closed‐loop SCVMI is simulated, and the hardware circuit is implemented and tested. All the results are illustrated to show the efficacy of this scheme. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation of diamondlike carbon films using nanopulse generator employing SI thyristor

Diamondlike carbon (DLC) films show high hardness, high electric resistivity, and the self‐lubricant characteristic, and many applications and synthesis methods have been reported. Pulse plasma chemical vapor deposition (CVD) is one of the synthesis methods suitable for DLC films on complicated form work, such as molding and extruding die. Ordinary, microsecond‐order pulse is used in this method. This paper describes the development of the synthesis method using nanosecond‐order pulse plasma CVD for DLC films. To realize this process, a static induction (SI) thyristor with an inductive energy storage (IES) circuit was used. Compared with microsecond, nanosecond‐order pulse plasma CVD method shows the characteristics of high electron temperature and exponential relationship between pulse frequency and growth rate. The characteristics of the thus‐obtained DLC films show two broad peaks of the disordered band at 1360 cm^?1 and the graphitic band at 1580 cm^?1 by Raman spectroscopy and hardness of 16.0 GPa and elastic modulus of 170 GPa. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(4): 1–7, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20341     

A high‐resolution hybrid digital pulse width modulator with dual‐edge‐triggered flip‐flops and hardware compensation

In this paper, a hybrid architecture of digital pulse width modulator (DPWM) which applies a counter, a phase‐shifted circuit, and a carry chain is proposed. Dual‐edge‐triggered flip‐flops are used in the phase‐shifted circuit to generate signals with 45° phase shift, which not only improves the resolution of the DPWM but also reduces the resource consumption in the carry chain. Furthermore, a hardware compensation method is used to solve the duty cycle increment phenomenon that affects the regulation accuracy of converter. An 11‐bit DPWM with the proposed architecture is implemented and tested by Xilinx Artix‐7 FPGA. The experimental results show a high resolution of 32 ps and a good linearity where R² is 0.99 and verify the effect of duty cycle compensation.     

Multistage multiphase switched‐capacitor DC–DC converter with variable‐phase and PWM control

A closed‐loop multistage multiphase switched‐capacitor converter (n‐stage p‐phase MPSC) is proposed with a variable‐phase control (VPC) and a pulse‐width‐modulation (PWM) technique for low‐power step‐up conversion and high‐efficiency regulation. In this n‐stage MPSC, n voltage doublers are connected in series for boosting the voltage gain up to 2ⁿ at most. Here, VPC is suggested to realize a variable multiphase operation by changing the phase number p and topological path for the more suitable level of voltage gain so as to improve the power efficiency, especially for the lower output voltage Besides, PWM is adopted not only to enhance output regulation for different desired outputs, but also to reinforce output robustness to source/loading variation. Further, some theoretical analyses and designs include: n‐stage p‐phase MPSC model, steady‐state analysis, conversion ratio, power efficiency, output ripple, stability, capacitance selection, and control design. Finally, the closed‐loop MPSC is simulated, and the hardware is implemented and tested. All the results are illustrated to show the efficacy of the proposed scheme. Copyright © 2011 John Wiley & Sons, Ltd.     

A 5‐Gbps low‐power low‐jitter voltage‐mode transmitter with two‐tap pre‐emphasis and impedance calibration in 65‐nm CMOS

A low‐power low‐jitter voltage‐mode (VM) transmitter with two‐tap pre‐emphasis and impedance calibration for high‐speed serial links is presented. Based on a comprehensive analysis of the relationship between impedance, supply current, and pre‐emphasis of the output driver, an impedance control circuit (ICU) is presented to maintain the 50 Ω output impedance and suppress the reflection, a self‐biased regulator is proposed to regulate the power supply, and an edge driver is introduced to speed up the signal transition time. Therefore, the signal integrity (SI) of the transmitter is improved with low power consumption. The whole transmitter is implemented in 65‐nm CMOS technology. It provides an eye height greater than 688 mV at the far end with a root‐mean‐squared jitter of less than 6.99 ps at 5 Gbps. The transmitter consumes 15.2 mA and occupies only 370 μm × 230 μm. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

PD time‐sequential properties of SF6 and SF6 gas mixture including CO2

This paper deals with partial discharge (PD) time‐sequential properties of SF₆/N₂/CO₂ ternary gas mixture as well as SF₆ and SF₆/N₂ gas mixture under AC and positive DC voltage applications. The measurements were carried out by changing the gas pressure up to 0.6 MPa and applied voltage with the N‐shape characteristics of breakdown voltage versus gas pressure for each tested gas considered. We obtained experimental results of the gas pressure dependence of maximum peak value of PD current pulse as well as the relationship between the time interval of PD pulses and the peak value of PD pulse. We discuss the mechanism of increase in breakdown voltage by adding CO₂ into SF₆/N₂ gas mixtures in terms of change of PD type from streamer to leader discharge. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(3): 32–40, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20073     

Active‐terminated transmitter and receiver circuits for high‐speed low‐swing duobinary signaling

In this work, we propose transmitter and receiver circuits for high‐speed, low‐swing duobinary signaling over active‐terminated chip‐to‐chip interconnect. In active‐termination scheme port impedance of transmitter and receiver is matched with characteristic impedance of the interconnect. Elimination of the passive terminators helps in reducing the transmitted signal level without degrading the 0signal detectability of the receiver. High‐speed current‐mode receiver and transmitter circuits are designed, so that the input port impedance of the receiver and the output port impedance of the transmitter are matched with characteristic impedance of the link. These Tx–Rx pair is used to validate the proposed active‐termination scheme. We also propose a duobinary precoder architecture suitable for high‐speed operation and a low‐power broadband equalizer topology for compensating the lossy long interconnect. The duobinary transmitter and receiver circuits are implemented in 1.8 V, 0.18 µm Digital CMOS technology. The designed high‐speed duobinary Tx/Rx circuits work up to 8 Gb/s speed while transmitting the data over 29.5 in. FR4 PCB trace for a targeted bit error rate (BER) of 10^?15. The power consumed in the transmitter and receiver circuits is 42.9 mW at 8 Gb/s. Copyright © 2010 John Wiley & Sons, Ltd.     

Dielectric characteristics of oil‐filled transformer in the presence of nonstandard lightning surge waveforms

To achieve a rational insulation design for transformers, it is important to evaluate dielectric strength against surges actually impinging on equipment on‐site. This paper deals with the breakdown voltage characteristics of an oil gap under nonstandard lightning surge waveforms combined with oscillatory voltages. It is found that the breakdown voltages of the oil gap under nonstandard impulse waveforms are higher than standard lightning impulse voltages. The results can be ascribed to V–t characteristics of the oil gap in short‐time impulse voltage ranges. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 39–45, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10229     

An accurate time‐domain model of transmission lines with frequency‐dependent parameters

Linear lossy two‐conductor transmission line can be modelled as dynamic two ports in the time domain, via the describing input and transfer impulse responses. This convolution technique is very effective when dealing with networks composed of transmission lines with frequency‐dependent parameters and non‐linear and/or time‐varying circuits. The paper carries out an accurate analysis of this model, in the most general case of lines with frequency‐dependent parameters. For such lines it is not possible to evaluate analytically the impulse responses, nor is it possible to catch them numerically, due to the presence of irregular terms, such as Dirac pulses, terms that numerically behave as Dirac pulses, and functions of the type 1/t^ρ with 0 < ρ <1. A simple method is proposed to evaluate exactly all the irregular terms of the impulse responses: once these irregular parts have been extracted, the regular remainders are easily evaluated numerically. This method is applied to analyse lines with frequency‐dependent parameters of practical interest, such as superconductor transmission lines, power lines above a finite conductivity ground, lines with frequency‐dependent dielectric losses and lines with normal and anomalous skin‐effect. Numerical simulations are carried out for illustration. Copyright © 2000 John Wiley & Sons, Ltd.     

Analysis and evaluation of waveform parameters for oscillating impulse voltage

This paper describes the effect of residual inductance of the impulse generator circuit. The analysis of waveform and the evaluation of waveform parameters were made for an oscillating lightning impulse. The peak value (overshoot factor or k‐factor), oscillation frequency, 30% value, 90% value, time to half‐value, and virtual origin are derived from the solution of third‐order derivative equation of the equivalent circuit. The comparison with the oscillating and standard lightning impulse was made. Also, the effects on overshoot, front time and the load‐side capacitance are theoretically clarified. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Breakdown characteristics of gas‐insulated switchgear for nonstandard lightning impulse waveforms under nonuniform electric field

To improve the insulation specification of gas‐insulated switchgear (GIS), it is necessary to recognize the insulation characteristics of SF₆ gas during actual surges (called nonstandard lightning impulse waveforms) occurring at field substations. The authors observed the insulation characteristics of SF₆ gas gap under various types of nonstandard lightning impulse waveforms and compared them quantitatively with those obtained with standard lightning impulse waveforms. The experimental results were used to derive an evaluation method for real surges, which was applied to typical surges for various UHV and 500‐kV systems. In the preceding study, therefore, only the case of a quasi‐uniform electric field (with a typical range of field utilization factors in the bus of a GIS) was investigated. In the present investigation, the insulation characteristics of an SF₆ gas gap for a nonuniform electric field were observed experimentally and an evaluation method for converting nonstandard lightning impulse waveforms equivalently to the standard lightning impulse waveform was investigated. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 11–18, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21144     

Quasi‐V2 hysteretic control boost DC–DC regulator with synthetic current ripple technique

Conventionally, a high accuracy operational amplifier (OPA)‐based current sensor is used for sensing current message under a full load range, which increases the cost characteristic. Instead of a high accuracy OPA‐based current sensor, this paper describes using a switching inductor quasi‐V² hysteretic control boost dc–dc regulator with a proposed current‐sensing technique named emulated‐ramp feedback (ERF), which can improve transfer efficiency under a full load range. Two control systems are presented in this paper. The first system, a hysteretic voltage control switching boost converter with ERF, achieves the hysteretic voltage control in a boost regulator and lowers the cost characteristic without using compensator. The second system, a quasi‐V² hysteretic voltage control switching boost converter with ERF, demonstrates the compatibility of ERF technique in rippled‐based control boost converters. The regulator was implemented with TSMC 0.25‐µm HV CMOS process. Experimental results show the second system can work under the specification of 5–12 V with a 0 to 300‐mA load range. Additionally, this system attained a recovery time is 27/95 µs for step‐up/step‐down in a 100 to 300‐mA continuous conduction mode load current, and a peak efficiency of 92.1% with a chip area of only 1.014 mm². Copyright © 2016 John Wiley & Sons, Ltd.