Characteristics of negative-resistance nonsinusoidal oscillators

This paper discusses the general characteristics of negative-resistance oscillators for which the voltage waveform across the active device consists not only of the fundamental voltage component but also of substantial harmonic voltage components. It is shown that a stability criterion, equivalent to that described by Kurokawa for sinusoidal voltage oscillators, must be satisfied at each frequency. The waveform components are derived from the fact that, when oscillating, the diode dynamic admittance at each frequency must always be equal to the negative of the load admittance at that frequency. The analysis is applied to two different practical circuits which give rise to LSA relaxation oscillations and good agreement is obtained between theory and experiment.