AMPLITUDE MODULATION CIRCUIT WHICH MAKES MODULATION FREQUENCY RESPONSE STABLE AND AMPLITUDE MODULATION

摘要

PURPOSE: To make constant the responsiveness of modulated wave by varying the amplitude of a modulating signal according to the difference between the amplitude of an input signal and the amplitude of the modulating envelope of an output signal and varying the amplitude of a gain control signal according to the difference between the amplitudes of the modulating envelope, and the modulating signal or each input signal. CONSTITUTION: A 2nd differential amplifier 18 is added to a conventional circuit, and an amplitude modulator is replaced with a variable gain amplitude modulator 20. The amplitude modulator 20 generates an output signal shown by Vrf, m, p=Vrf, i Vm Vp Km. Here, Vp is a gain control signal, Vp Km is the variable gain of the amplitude modulator 20, Vrf, i is career wave, and Vm is a modulating signal. This amplitude modulating circuit generates a modulated output signal Vrf, o, and this has a career wave signal frequency Wrf which is determined by the frequency of the career wave signal, an amplitude Vrf, o, and a modulating frequency Wc which is determined by the amplitude and the frequency of the modulating signal Vc. Thus, the responsiveness of the modulated wave is to be constant.