| 摘要 |
PURPOSE:To reduce the number of MOS transistors (TRs) of the entire circuit by using a counter so as to reduce the number of MOS TRs required for signal processing by one bit in a pulse width modulation circuit by the count control using a counter. CONSTITUTION:The titled circuit includes control circuits 23, 29, the control circuit 23 inputs a pulse from a counter 22 and outputs alternately control pulse signals X, Y at every time this signal is inputted and a modulation output signal C where H, L level are converted is outputted. The control circuit 29 inputs a output signal signifying a prescribed numeral from a register 30 and the signals X, Y, and when the signal X is inputted, the output signal from the register 30 is used as a preset signal to be outputted to the counter 22 as it is, and when the signal Y is inputted, the complement signal of the output signal from the register 30 is used as a present signal and outputted to the register 30. The output signal from the register 30 is used as a preset signal and the length of H/L of the modulation output signal is decided by inputting alternately the signal to the counter 22, then one counter is enough for the circuit.
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