Generation of high-speed waveforms using nonlinear delay lines

Abstract

In nonlinear delay lines employing back biased p-n junctions as variable capacitors, the velocity of propagation is a function of signal amplitude. This effect may be used to produce short-risetime pulses which may be of high repetition rate. Two circuit applications are discussed, these being the processing of sinewaves to produce fast-edge triangular pulses, and also the processing of long-risetime pulses to produce short-risetime pulses. The analysis employed is in the time domain, and stems from linear delay-line theory, relying upon certain qualifications and restrictions being imposed when applied to nonlinear delay lines. This approach produces good agreement with experimental results. The questions of `ringing? and overshoot are discussed in some detail, and design criteria are obtained for eliminating these undesirable features from delay lines.