Theoretical analysis of the loop-gain modulator

A recently introduced concept in amplitude modulation circuits is based on the modulation of the loop gain of a sinusoidal feedback oscillator. A model for the loop-gain modulator is proposed and discussed. The linearity of modulation for either the class-A or class-C stage is excellent for modulation indexes that approach unity. This linearity is comparable to that of the collector modulation circuit. The modulation source power requirement is minimized by placing this source in the base circuit of the transistor. The power requirement for the modulation source is two to three orders of magnitude less than that of the collector modulation circuit