| 摘要 |
PURPOSE:To simplify the LPF to obtain the DC voltage, by branching the output of pulse width modulation into a plurality of paths, and superimposing this output signal on different DC potential with a plurality of voltage dividing resistors for synthesis. CONSTITUTION:The frequency division output of the sweep out counter circuit 16 of the pulse width modulation circuit 11 is input to the counter circuit 21 to constitute the change-over means. In the circuit 21, the output signal in 2 bits is input to the gate circuit 22, where the pulses in four states of the circuit 21 are independently output to control the gate circuit 23 with the pulses in this state. The gate circuit 23 switches and selects the path of conduction of the pulse width modulation output from the circuit 11, depending on the state of pulse from the circuit 22. The output of the circuit 23 is input to the synthesis circuit 24 synthesizing the DC components. The circuit 24 divides the power supply voltage VP at the resistances R1- R4 to control the conduction of the transfer gates TG0-TG4 with the output pulse from the circuit 23, and the pulse width modulation signal is superimposed on the DC potential divided for output and the DC voltage is output via the LPF25. |
