Large-signal Equivalent Circuit Model Research Articles

A large-signal equivalent circuit model for substrate-induced drain-lag phenomena in HJFETs

A large-signal HJFET model is developed for drain-lag phenomena caused by deep traps beneath the channel. The model is based on the self-backgating and Shockley-Read-Hall (SRH) statistics. It is shown by two-dimensional (2D) device simulation that electron capture in deep traps is much faster than electron emission under large-signal conditions; therefore, drain current exhibits different responses for rising and falling steps of applied voltage. In the circuit model, electron capture and emission in deep traps are expressed by a parallel circuit consisting of a diode and a resistor, which are physically deduced from SRH statistics. The model agrees well with the 2D simulation results and experimental current-transient data for large-signal voltage steps. In addition, this model accurately describes small-signal drain-conductance dispersion and temperature effects on the trapping phenomena.

A parameter extraction method using cutoff measurement for a large-scale HSPICE model of HBT's

We present an accurate parameter extraction method for the HBT large-signal equivalent circuit model in which several extrinsic parasitics are connected to HSPICE BJT model. The measured Gummel plot are used to extract DC model parameters of HBT using HSPICE. Capacitances are then obtained from S-parameter measurements of the HBTs biased to cutoff. The other parameters are determined from the active device S-parameters. The large-signal modeled Gummel plot and S-parameters show good agreement with the measured ones, respectively.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New physical timing models of bipolar nonsaturation logic using current-domain analysis technique

A new large-signal equivalent circuit with input and output current signals for a nonsaturated bipolar junction transistor has been developed. Based upon this equivalent circuit, physical timing models of direct-coupled transistor logic (DCTL) and nonthreshold logic (NTL) have been derived through a general modeling methodology. It is shown from extensive comparisons with SPICE simulation results that the models have a maximum error of 25% in single-stage delay calculation and 10% in multi-stage delay calculation. Experimental results on NTL ring oscillators also partly substantiate the developed current-domain large-signal equivalent circuit and physical timing models. Good accuracy, wide applicable ranges of device/circuit parameters and input waveforms, and less CPU time and memory consumption than full transient simulations make the physical timing models feasible in optimization and CAD of high-speed bipolar ICs.

Intrinsic GaAs MESFET equivalent circuit models generated from two-dimensional simulations

An accurate, physically based two-dimensional GaAs MESFET model is used to generate small-signal and large-signal equivalent circuit models useful for the evaluation of GaAs device structures and GaAs integrated circuits. The models and the simulation techniques described provide a useful means of evaluating RF performance on the basis of the physical properties of the FET. As an example, the small- and large-signal device characteristics are evaluated as a function of drain-source bias voltage and lattice temperature for a 0.8- mu m gate length FET. The small-signal results show severe degradation of frequency response with increase of drain-source bias voltage because of a high electric field in the conduction channel. The large-signal results show that the decrease in RF power capability with temperature increase is primarily due to declining current capability with temperature.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Multimode analysis of semiconductor lasers through a large signal nonlinear equivalent circuit model

AbstractA multimode rate equation analysis of the semiconductor laser including the effects of nonlinear gain is presented. A large signal equivalent circuit model is used to determine the response of the laser. The analysis has been applied to the direct intensity modulation of individual longitudinal modes as well as to the transient response of the laser under different excitation schemes.

Large signal nonlinear distortion prediction for a single-mode laser diode under microwave intensity modulation

The large-signal nonlinear distortions from a directly-modulated single-mode GaAlAs laser diode are closely predicted by using a large-signal equivalent circuit model. Criteria for determining intrinsic parameter values are described. The simulations are done in the time domain and then transformed to the frequency domain by FFT. Second harmonics, two-tone third-order intermodulation, multicarrier intermodulation, and intermodulation due to two arbitrarily separated tones have all been simulated and match well with corresponding measured results.

Approaches to resists for two-level RIE pattern transfer applications : E. Reichmanis, G. Smolinsky and C. W. Wilkins Jr.Solid St. Technol., 130 (August 1985)

The paper presents a compact D-band monolithic sub-harmonic mixer (SHM) with 3 μm planar hyperabrupt schottky-varactor diodes offered by 70 nm GaAs mHEMT technology. According to empirical equivalent-circuit models, a wide-band large signal equivalent circuit model of the diode is proposed. Based on the extracted model, the mixer is implemented and optimized with a shunt-mounted anti-parallel diode pair (APDP) to fulfill the sub-harmonic mixing mechanism. Furthermore, a modified asymmetric three-transmission-line coupler is devised to achieve high-level coupling and minimize the chip size. The measured results show that the conversion gain varies between −13.9 dB and −17.5 dB from 110 GHz to 145 GHz, with a local oscillator (LO) power level of 14 dBm and an intermediate frequency (IF) of 1 GHz. The total chip size including probe GSG pads is 0.57 × 0.68mm2. In conclusion, the mixer exhibits outstanding figure-of-merits.

Large-Signal Equivalent-Circuit Model of a GaAs Dual-Gate MESFET Mixer (Short Papers)

A large-signal equivalent-circuit model of a GaAs MESFET mixer containing twelve elements, of which eight are voltage-dependent, is solved in the time domain for Iocal oscillator and frequencies of 9.5 GHz and 10.0 GHz, respectively. The results variation of conversion gain with local oscillator and signal power and are in good agreement with measured values. The model is formulated in such a way that material/device/circuit interactions can be yielding information on the preferred device structures and biasing conditions.

JFET Transient Radiation Response

A comprehensive study of transient radiation response mechanisms in Junction Field Effect Transistors at dose rates less than 1 × 1010 Rad (si)/sec has been performed. Theoretical models of device response have been developed and represented in terms of a large signal equivalent circuit model. Experimental verification has been achieved through radiation testing at the AFCRL Linac Facility on specially built JFETs supplied by Siliconix, Inc. The complete results of the work are documented in Reference 1, and the conclusions are presented in this paper.