Small-signal Equivalent Circuit Model Research Articles

A discrete element small-signal equivalent circuit for forward-biased p+n diodes containing deep levels

A discrete element small-signal equivalent circuit model for p- n diodes containing deep defect levels is developed, by extending an existing model for undamaged devices. With the aid of a simple analytical expression which accurately describes the forward bias d.c. current, the enhanced small-signal conductance due to carrier recombination in the depletion region is included in the model. The influence of trapped charge on the space charge capacitance is incorporated using a simplified version of the analysis of Beguwala and Crowell. The predictions of the model are verified by experimental data from silicon p + n diodes, in which deep levels have been induced by electron irradiation. It is shown that the deep level activation energies may be estimated from the forward bias capacitance-voltage characteristics, yielding values which agree well with those obtained by established techniques.

Small signal equivalent circuit model for the metal-insulator-semiconductor tunnel diode : V. A. K. Temple and J. Shewchun, Solid-St. Electron.21, 807 (1978)

Small signal equivalent circuit model for the metal-insulator-semiconductor tunnel diode : V. A. K. Temple and J. Shewchun, Solid-St. Electron.21, 807 (1978)

Microwave characterization of GaAs MESFET and the verification of device model

The elements in the small-signal equivalent circuit model of a microwave GaAs MESFET have been related to the device parameters (i.e., device structure, semiconductor properties, and operating point) by device theories. This equivalent circuit is experimentally verified by small-signal 3-GHz microwave measurements at room and liquid-nitrogen temperatures. The method used for determining the values of equivalent circuit parameters is briefly described.

Application of the small-signal transmission line equivalent circuit model to the a.c., d.c. and transient analysis of semiconductor devices

It is shown that the use of the small signal transmission line equivalent circuit model is not restricted solely to the small signal a.c. analysis of semiconductor devices. Simple algorithms are described which allow it to be used to compute the d.c. and the large signal transient properties of semiconductor devices to any desired precision. The approach is demonstrated by computing the a.c., d.c. and transient properties of an N + P junction diode.

Circuit Model for Characterizing the Nearly Linear Behavior of Avalanche Diodes in Amplifier Circuits

A nonlinear circuit model for avalanche diodes is proposed. The model was derived by assuming that the bias dependence of the elements in a known small-signal equivalent-circuit model for existing diodes arises in a manner consistent with the theory of an idealized Read-type device. The model contains a nonlinear RL branch, a controlled source, and a linear depletion capacitance. The model is used in the nearly linear sense to predict intermodulation distortion (IMD) and gain compression in avalanche diode amplifiers. Computed results for amplifiers with existing diodes are shown to be in good agreement with experiment.

Exact analytical solution of high frequency lossless MOS capacitance-voltage characteristics and validity of charge analysis

The small signal equivalent circuit model is employed to obtain the exact nonuniform transmission line for high frequency MOS capacitance calculations. The semiconductor capacitance, given by the open circuit input capacitance of the line, is described by a simplified Riccati equation which is valid for arbitrary impurity distribution in an extrinsic semiconductor. Numerical solutions are obtained using the fourth order Runge-Kutta method for the case of constant impurity concentration. The validity range (measured by the amount of surface band bending) and the accuracy of the various approximations of the capacitance calculations using charge analysis are established by comparing with the exact solution from the transmission line. It is shown that for doping greater than 10 14/cm 3, the complete minority carrier depletion model gives accuracy better than 10 −6 C 0 for carrier concentration ratio of (majority/minority) > 500 at the oxide-semiconductor interface, or U IS > 2 U F −6. For stronger surface inversion, the high frequency charge analysis formula can be used with equal or better precision. It is noted that the exact transmission line model used here to verify the charge models is particularly valuable for substrates with spatially varying impurity concentration.