| 摘要 |
PURPOSE:To decrease the number of connection pins of a tap coeficient setting element and reduce the tap area by constituting a circuit having the same performance with plural roll-off filters by using shift registers and one resistance block. CONSTITUTION:When a signal SQ from the Q output terminal of an FF15 is at a low level and variable terminsl of switch circuits 171-17n are conneced to A- side fixed contacts respectively, outputs of (n) stages of shift registers 13 are obtained at the movable terminals of the circuits 171-17n. Then, the output of a resistance block 18 which sums up the signals is supplied to sample holding circuits 211 and 212 and the sum signal sampled and held by the circuit 211 is outputted from a terminal 251. On the other hand, when the signal SQ is at a high level and the circuits 171-17n are connected to B-side fixed terminals, the sum signal obtained through the resistance block is supplied to the circuits 211 and 212 and the sum signal sampled and held by the circuit 212 is outputted from a terminal 251. |
