Time Domain Analysis Of Circuits Research Articles

Energy-based control of numerical errors in time-domain simulation of dynamic circuits

In this paper, we consider the accuracy of integration algorithms such as the implicit Euler and the trapezoidal methods, which are largely employed in the time domain circuit analysis. These algorithms require one to make hypotheses on the intersample shape and on the "energy content" of the sampled waveforms. For example, the implicit Euler algorithm supposes functions to be piecewise constant, When these hypotheses are violated, some errors are introduced by the integration process into the solution waveform. We consider the energy of the sampled functions, and through energy balance equations, estimate the accuracy of the integration algorithm. Furthermore, we propose an implicit algorithm to determine an adequate integration time step during numerical time domain analysis. This algorithm is based on a global energy balance equation and not on the conventional estimation of the local truncation error. It avoids the "cut and try" mechanism used in SPICE to determine the time step that satisfies the desired error tolerance.

A new ideal switch model for time-domain circuit analysis

An ideal switch model may be needed for the simulation of various real and idealized circuits. A straightforward implementation of an ideal switch model may, unfortunately, produce a zero pivot during the circuit matrix decomposition. In order to avoid such problems a new model of the switch is proposed that retains the structure of the non-zero elements in the circuit matrix, no matter what is the state of the switch. This excludes singularity problems. The switch is viewed as a nonlinear two-terminal element changing its resistance from zero to infinity, thus simulating a closed and open switch, respectively.

Corona Considerations in Submarine Cable Communications Systems

Underwater repeatered telephone cable systems are series powered by high-voltage dc. Each repeater and equalizer contains a power separation filter (PSF) for extracting the dc current from the center conductor of the coaxial cable while allowing signal transmission. Corona discharges occurring across the high-voltage components are coupled through reactive components to the repeater's terminals. Each of the experimentally observed pulse shapes emanating from a discharge in the power filter must be evaluated to determine the effect on both system data transmission and reliability objectives. The response to surface corona discharges across the dielectric of the high-voltage capacitors has been successfully duplicated without high voltage by applying current pulses to the appropriate electrodes. This technique in conjunction with artificial contamination of dielectric surfaces and cataloging of the resultant discharge waveforms has led to identification of the major corona sources in the telephone repeater and consequently, to a factory testing program for components and assembled networks that assures satisfactory corona "free" units. The experimental results have also been successfully simulated numerically with a time domain circuit analysis comiputer program which has proved useful in establishing limits for the testing program.