| 摘要 |
PURPOSE:To eliminate pop noise at switching, by switching a signal source according to the switching instruction signal of a switch through a output from a comparator when a DC voltage is equal to a pulsating voltage superimoposing a signal on the DC voltage. CONSTITUTION:A comparator 8 which inputs an output of a pulsating signal source 6 superimposing a voltage of a DC power supply 4 on a signal from a signal source 5 and an output of a reference voltage source 7 having the same DC voltage as the DC power supply 4, is provided, and a muting circuit 10 is constituted, which switches a signal from the signal source 6 with an output (e) of the comparator 8 and a switching instruction signal (f) from a switch 9. When a pulsating voltage of the signal source 6 is equal to the DC voltage 7, an output 11 switching a signal from the signal source 6 according to the switching state of a switch 9 through an output (e) of the comparator 8 is obtained. Thus, the cause of pop noise due to a transient phenomenon at switching can be eliminated and a circuit which is ease in semiconductor circuit integration can be achieved. |
