Numerical device simulation of the composite triple-beat distortion of a cable television amplifier

The composite triple-beat (CTB) distortion of a cable television amplifier was simulated using numerical device simulation. The structures for the underlying bipolar transistors were created using numerical process simulation. Subsequent time-domain device simulation was performed in a mixed device-circuit mode for a 77-carrier input signal with a random phase relationship between carriers. Using a novel mathematical technique, the turn-on transient of the amplifier was subtracted from the periodic part of the output signal in order to reduce the simulation time required to resolve the CTB distortion. A Fourier transform mapped the resulting signal into the frequency domain, where the CTB distortion could be determined directly. This simulation methodology demonstrates the capability of correlating circuit level radio frequency figures of merit with the process conditions in a technology.