To provide a pulse-width modulation circuit having a new constitution capable of being applied to a multichannel type audio device or the like, and using a monostable multivibrator.
The pulse-width modulation circuit pulse-width modulates an audio signal, and outputs the modulation signal. The pulse-width modulation circuit has a monostable multivibrator circuit 1 generating output pulses by a synchronism with a trigger pulse signal having a constant frequency and a constant-current circuit 2 supplying the monostable multivibrator circuit 1 with a constant charging current. The monostable multivibrator circuit 1 has a capacitor C1 for a charging charged by the constant charging current supplied from the constant-current circuit 2; and first and second transistors Q1 and Q2 using the potential of the input audio signal as a reference potential in the case of the start of the charging or the case of a completion by the capacitor C1 for the charging, and changing the pulse width of the output pulses on the basis of a charging time by the capacitor C1 for the charging.
HANDA JINKO
KASAI JOJI
FUJIOKA SO
Tatsuya Tanaka
Tsukasa Senba
Hiroshi Furusawa