PURPOSE: To execute highly precise multiplication with a simple constitution by executing pulse width-modulation in accordance with either of two analogue signals, executing amplitude-modulation with setting the signal which has been pulse width-modulated to correspond to the other analogue signal and obtaining the multiplied value of two analogue signals with averaging them.
CONSTITUTION: Only the amplitude of the signal (c) which has been pulse width- modulated in a duty variable free-running multi vibrator 1 corresponds to that of the input analogue signal B and changes in a pulse amplitude modulation circuit 2 with a pulse width as it is. When the input analogue signal B has the same sine wave as the input analogue signal A, the pulse amplitude modulation circuit 2 outputs a signal (d) in which the wave height value of the waveform of the signal (c) is set to correspond to the amplitude of the waveform of a signal (b) so as to be changed. The areas of respective pulses in the signal (d) show the multiplied values A×B of the signal A and the signal B. Namely, the signal (d) is averaged in a low-pass filter circuit 3, and an output signal (e) becomes the multiplied value of the input signal A and the input signal B. Thus, an accurate operation is attained and the multiplication circuit of low-cost can be obtained.
TAKAO KATSUTOSHI
KUSADA TOKUTARO
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