Inversion Circuit Research Articles

Low-cost capacitor voltage inverter for outstanding performance in piezoelectric energy harvesting

The purpose of this paper is to propose a new scheme for piezoelectric energy harvesting optimization. The proposed enhancement relies on a new topology for inverting the voltage across a single capacitor with reduced losses. The increase of the inversion quality allows a much more effective energy harvesting process using the so-called synchronized switch harvesting on inductor (SSHI) nonlinear technique. It is shown that the proposed architecture, based on a 2-step inversion, increases the harvested power by a theoretical factor up to square root of 2 (i.e., 40% gain) compared with classical SSHI, allowing an increase of the harvested power by a factor greater than 1000% compared with the standard energy harvesting technique for realistic values of inversion components. The proposed circuit, using only 4 digital switches and an intermediate capacitor, is also ultra-low power, because the inversion circuit does not require any external energy and the command signals are very simple.

Eric Vittoz and the Strong Impact of Weak Inversion Circuits

In a groundbreaking and now classic 1977 paper, Eric Vittoz and J. Fellrath meticulously characterized and developed models for devices operating in the weak inversion region, as well as a variety of circuit building blocks that could operate and exploit the exponential characteristics in this region. Their killer application -- the electronic watch -- employed techniques that are now used in a score of low-voltage, micropower applications, such as biomedical devices, hearing aids, pagers, sensor interfaces, motion detectors for pointing devices, and a variety of portable instruments. This tribute to Vittoz as an educator and industrial researcher is by Yannis Tsividis of Columbia University, an esteemed scientist and educator in his own right.

Three-channel KrF laser with distributed magnetic-switch-based charging circuit

A novel magnetic-switch-controlled L−C inversion circuit is proposed for discharge pumped excimer lasers of three separate channels. The charging circuit is controlled by one thyratron and one common “distributed” magnetic switch. Stable synchronization of the channels and the capability for amplification or generation of three separate pulses of constant delay are unique features of this scheme.

Reliable Self-Starting Simmer Circuit for a Marx-Bank Driver

A reliable self-starting simmer circuit for use as a Marx-bank driver, in which a stable glow discharge is obtained using the high voltage main power supply instead of an additional simmer power supply, is presented. Highly energetic excitation sources having very short pulse width are needed in powerful dye and excimer lasers. For this reason, multi-stage Marx-bank circuit and LC inversion circuits have been developed. However, these circuits have defects in the interference between the main discharge circuit and the pre-ionization circuit, and an occasional switching failure of the spark gap switch, resulting in an unstable main discharge. The circuit presented seeks to address these issues.

AC Electronic Transformer

PROBLEM TO BE SOLVED: To reduce the size of an AC transformer by providing a polarity inversion circuit on an input line and inverting the winding current at high speed so that the flux has no chance of growing significantly thereby reducing the volume of a magnetic body. SOLUTION: A high frequency circuit comprises a polarity switching high frequency switch 2 and a high speed reswitching switch 4 provided, respectively, at the input and output so that the switch elements are bi-directional. When the switch element is driven in synchronism with the input side, polarity is reinverted to reproduce the original low frequency component. Consequently, the voltage is converted while sustaining the waveform accurately and bidirectivity of current flow is sustained automatically without requiring any control and the size of a power converter can be reduced as required depending on the switching frequency.

A series-resonant DC/AC inverter for impedance-load drives

A DC/AC inverter without cycloconversion configured by a half-bridge series-resonant inversion (HB-SRI) circuit is presented. The inverter is a series resonator with two auxiliary switches in shunt with the resonant capacitor so as to configure adaptively the output current suitable for impedance load. The output sinusoidal voltage is synthesized by a series of equal-amplitude quasisinusoidal pulses (QSPs) and the corresponding current is formed by unequal QSPs and adaptively phase-shifts to the impedance load. The presented HB-SRI is operated by frequency modulation with a constant-on time control. System modeling and waveform syntheses for the output sinusoidal voltage and its current are clearly derived, A typical design example of a 500 W HB-SRI inverter is examined to assess the system performance. The power efficiency is over 90% when the inverter output is above 200 W. The total harmonic distortions (THDs) for various impedance loads are all within 6%.

Robust subthreshold logic for ultra-low power operation

Digital subthreshold logic circuits can be used for applications in the ultra-low power end of the design spectrum, where performance is of secondary importance. In this paper, we propose two different subthreshold logic families: 1) variable threshold voltage subthreshold CMOS (VT-Sub-CMOS) and 2) subthreshold dynamic threshold voltage MOS (Sub-DTMOS) logic. Both logic families have comparable power consumption as regular subthreshold CMOS logic (which is up to six orders of magnitude lower than that of normal strong inversion circuit) with superior robustness and tolerance to process and temperature variations than that of regular subthreshold CMOS logic.

A low latency architecture for computing multiplicative inverses and divisions in GF(2/sup m/)

A low latency architecture to compute the multiplicative inverse and division in a finite field GF (2/sup m/) is presented. Compared to other proposals with the same complexity, this circuit has lower latency and can be used in error-correction or cryptography to increase system throughput. This architecture takes advantage of the simplicity to computing powers (2/sup l/) of an element in the Galois Field. The inverse of an element is computed in two stages: power calculation and multiplication. A division can be performed using only one more multiplication in the inversion circuit.

Energy characteristics of a XeCl-laser with excitation by anLC-inverter

We present results of research on the effect of the parameters of an XeCl-laser excitation system patterned after an LC-inverter on the energy characteristics of the laser. The effect of each of the parameters and their collection is established. We obtained conditions for matching the parameters of the excitation circuit of an XeCl-laser on satisfaction of which the lasing energy acquires a maximum value. It is shown that the energy characteristics of the laser are determined by the processes occurring in the inversion circuit and by the dynamics of the voltage across the interelectrode spacing.

Finite field inversion over the dual basis

In this transaction brief we consider the design of dual basis inversion circuits for GF(2/sup m/). Two architectures are presented-one bit-serial and one bit-parallel-both of which are based on Fermat's theorem. Finite field inverters based on Fermat's theorem have previously been presented which operate over the normal basis and the polynomial basis. However there are two advantages to be gained by forcing inversion circuits to operate over the dual basis. First, these inversion circuits can be utilized in circuits using hardware efficient dual basis multipliers without any extra basis converters. And second, the inversion circuits themselves can take advantage of dual basis multipliers, thus reducing their own hardware levels. As both these approaches require squaring in a finite field to take place, a theorem is presented which allows circuits to be easily designed to carry out squaring over the dual basis.

Continuously tunable high-pressure CO/sub 2/ laser for spectroscopic studies on trace gases

A high-pressure CO/sub 2/ laser with unique characteristics in terms of continuous tunability and emission bandwidth is presented. It is operated at a pressure of 11.5 bar and transversely excited by short, high-voltage pulses generated by a double LC inversion circuit. Auxiliary discharges parallel to the electrodes provide a sufficient free-electron density through UV ionization of the laser gas mixture. The laser resonator consists of a near-grazing-incidence grating setup in which the grating is positioned at a large incidence angle of 77/spl deg/. A theoretical model for the calculation of the emission bandwidth is presented and its predictions are compared to direct measurements and show excellent agreement. The achieved very narrow bandwidth of 0.018 cm/sup -1/ constitutes the ultimate wavelength resolution of any detection system using this laser as radiation source. It allows the resolution of any fine structure in the spectra of absorbing gases at atmospheric pressure. Continuous tunability has been achieved over 76 cm/sup -1/ between 932 cm/sup -1/ and 1088 cm/sup -1/ with minimum pulse energies in excess of 10 mJ. The narrow bandwidth precludes the occurrence of mode-pulling effects so that the laser exhibits a linear wavelength tuning behavior throughout the entire emission range. The calibration of the laser wavelength is performed by photoacoustic measurements on low pressure CO/sub 2/ gas. An absolute accuracy of /spl plusmn/10/sup -2/ cm/sup -1/ is achieved. A great potential improvement in detection selectivity can thus be expected from a scheme with the high-pressure CO/sub 2/ laser as radiation source.

High-speed circuits for TE discharge lasers and high-voltage applications

Pulsed transverse electric (TE) glow discharges used to produce population inversions in gas lasers at 1–20 atm require high-speed, high-voltage, high-current capacitor banks. In this article we first review and compare the circuits in common use to produce the required fast, self-sustained glow discharges in CO2, excimer, and N2 lasers. The parameters and circuit types given will be useful to future designers of pulsed gas lasers to design and to optimize any proposed circuit in order to yield any desired operating conditions and parameters. The n-stage circuit types presented are capacitor-transfer (C-C), L-C inversion, Marx bank, and fourfold L-C inversion, with their double-sided counterparts, and also their transmission-line counterparts, such as the Blumlein circuit. A one-parameter differential equation is developed which describes the general series C-L-R circuit. Electrical pulses measured on various lasers are compared with the differential equation solutions for various bank impedances and load resistances. We then present the design and measurements of a new automatically preionized, double-sided, L-C inversion circuit for an 800-mJ, TE CO2 laser, and compare it to previous systems. Methods to lengthen the discharge pulse, and some novel active mode locking techniques are discussed. We compare the L-C inversion circuit, the fourfold L-C inversion circuit, the conventional Marx bank, and the ‘‘double Marx bank’’ for lasers and other applications, such as pulsed particle accelerators. Finally, we discuss capacitor bank interconnections, electro-optic probe systems, and various triggering methods.

Self-consistent modelling of X-ray preionized XeCl-laser discharges

In this theoretical work a 0-D model for a self-sustained X-ray preionized XeCl-laser discharge is presented. The model is self-consistent in the sense that it simultaneously solves, contrarily to the usual decoupling procedure, the Boltzmann equation for electrons, the kinetic equations for excited and ionic species, the equations for the electrical circuit and the laser photon density. It includes a rather complete kinetics of HCl(v) vibrational excitation, dissociation and dissociative attachment. The influence of electron collisions with excited species and of e-e Coulomb collisions on the plasma parameters and transport coefficients is discussed. Some evidence of the non-stationary equilibrium between the electron distribution and the reduced electric field E/N is given. Results of the model are compared with experimental ones corresponding to a XeCl-laser discharge driven by a L-C inversion circuit. The model predicts well the main trends for the variation of the laser energy in a large range of experimental conditions. The discrepancy between experiment and model for absolute values of the laser energy is discussed.

Integrated inversion channel optoelectronic devices and circuit elements for multifunctional array applications

An approach to laser-based optoelectronic integration is described. It is shown that by using a single epitaxial growth structure and a common processing sequence, all the electrical and optical devices required for a complete optoelectronic integrated circuit (OEIC) are realized. The demonstrated individual device performance and the implementation of an integrated combination of devices are discussed. Such applications as the implementation of a basic building block for a 2*2 smart-pixel switching node are discussed. A comparison to other laser- and modulator-based approaches is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Use of Insulated Gate Bipolar Transistors in an All Solid State Exciter for Multikilowatt Average-power, TEA CO2 Lasers.

Using insulated gate bipolar transistors (IGBT), we constructed an efficient, all solid state exciter for high efficiency, high power operation of a transversely excited atmospheric (TEA) CO2 laser. The exciter was composed of a high-voltage pulse generator and a two-stage magnetic pulse compressor. Forty-eight series and two parallel IGBTs were used as the main switch of the pulse generator. The maximum switching voltage as high as 36 kV was achieved with a transfer energy of about 100J. The pulse generator, employing an LC inversion circuit, produced a 65 kV, 7.5μs pulse, which was compressed to 0.5μs by the pulse compressor. The use of an IGBT stack decreased energy waste in a snubber circuit, resulting in a high efficiency of more than 90%. By applying the exciter to a TEA CO2 laser with a discharge volume of 0.5l, an average laser power of 4.6 kW was attained at a repetition rate of 550 pps for a switching energy of 78J. The overall efficiency of the laser was as high as 10.5%. A repetition rate of 1.1 kpps was attained, resulting in an average laser power of 3.4 kW by reducing the switching energy to 42J.

High gain, multiatmosphere CO2 laser amplifier

A novel TE discharge, 15-mm aperture, multiatmosphere, CO2 laser amplifier is described, with measured electrical characteristics and gain measurements on the 9.294-μm, 9R(16) line. The electrical circuit used in this amplifier is a realistic alternative to the Marx bank or conventional LC inversion circuit and, similarly, it would be useful for excitation of other gas lasers as well. This automatically preionized, double-sided, fourfold LC inversion circuit uses only one spark gap, and it is shown to provide small-signal gains of 5.7% cm−1, at 120 J l−1 atm−1 and 10 atm. The generalization to an n–stage device, which would be suitable for higher pressures, and larger apertures, is discussed.

Synchronizable, injection-locked, Q-switched, mode-locked, and cavity-dumped ten-atmosphere CO2 laser

A novel, active, mode-locking scheme for producing single, line-tunable, high-power ultrashort CO2-laser pulses is described. Using an auxiliary grating-tuned cw CO2 laser for injection locking on the 9R(16) line, the Q-switched, mode-locked, and cavity-dumped 10-atm CO2 laser produces single, detection-limited (&amp;lt;500 ps) pulses of 5-mJ energy at λ=9.29 μm. Details are given on the traveling-wave GaAs Pockels cells, both of which are controlled by a single, ultraviolet (UV) triggered spark gap. The time-locked output pulse is delayed by precisely 300.7 ns with &amp;lt;±50 ps jitter against the UV triggered spark gap, so the laser pulse is synchronizable to an external event to &amp;lt;±250 ps. To drive the transverse-electric (TE) 10-atm amplifier section, instead of the conventional Marx bank or inductance-capacitance (LC) generator, a new type of circuit is used. The automatically preionized, double-sided LC inversion circuit uses only one spark gap, and a detailed description with operating characteristics is provided.

The effect of circuit inductance on the operation of a TEA CO2laser

The effect of the inductance in an LC inversion circuit on the stable operating voltage range and output of a TEA CO2 laser has been investigated. The inductance value determines the laser electric/optical energy conversion efficiency and output peak power. In addition, the rate of dissociation of CO2 in the laser discharges was found to depend on the inductance. The observations are shown to be consistent with a change in the value of the ratio of electric field to neutral gas number density, E/N, at which energy is deposited into the discharge.

A Quick-Look Decoder with Isolated Error Correction and Node Synchronization

In a low-noise environment, a simple inversion circuit can be used for quick-look decoding of a convolutional code. The bit error performance of the raw inversion circuit is improved by a simple pattern-recognition technique operating on the syndrome stream, which is also used to acquire node sync.

Properties of pulsed gas lasers pumped by LC inversion circuit made of BaTiO3 and SrTiO3 series ceramic capacitors

Properties of pulsed gas lasers pumped by LC inversion circuit made of BaTiO3 and SrTiO3 series ceramic capacitors were experimentally investigated. The effects of a decrease in capacitance at higher charging voltages on TEA CO2 and TE N2 laser performances were clarified in terms of discharge voltage, current, power pulse, real stored energy and the energy deposited into the discharge load. Laser performances of the TEA CO2 and TE N2 lasers with the SrTiO3 series capacitor used as an energy storage element of the LC inversion circuit were found to be superior to that of the BaTiO3 series capacitor used.