A wideband amplitude modulator as a special silicon integrated circuit

A transistor circuit for silicon integrated circuit construction incorporating a new design of modulator is described. The circuit is associated with a microphone amplifier and r.f. input stage. The output consists of an amplitude modulated carrier in which the a.f. components have been suppressed. The circuit is suitable for modulation frequencies well into the video range and carrier frequencies up to about 20 MHz, the behaviour being predictable over a wide range of conditions. The specifications meet those laid down for integrated circuits generally.