A system and method for amplitude modulating a carrier signal with an audio or other information input signal relies on multivibrators and comparators initiating a logic controlled processing technique for providing two sinusoids, each a fundamental frequency waveform, the two having a mutual phase relationship defined by intermediate processing steps such that they differ in phase from 0 to 180 electrical degrees. The comparators output first resultant pulses when the carrier signal is greater than the amplitude of the audio or other information input signal. The first resultant pulses are input to a logic processing network to trigger multivibrators which output overlapping 180.degree. wide pulses, respective phase shifted resultant signal waveforms being formed from the respective comparator outputs. In the output stage, the respective resultant waveforms are amplified and filtered to form the two sinusoids which are added vectorially to form an amplitude modulated output signal which varies linearly with the audio or information input signal.