| 摘要 |
PURPOSE:To perform monolithic IC-implementation and to vary gain settings, by using an analog switch consisting of a field effect transistor as a switching means, and using a locked resistance network as a feedback resistance circuit. CONSTITUTION:A locked resistance network 13 is inserted between the output terminal of a differential amplifier 11 and a reference terminal 17. An optional connection point in the network 13 is selected previously in accordance with a necessary gain setting program, and then connected to the out-of-phase input terminal of the amplifier 11 through an analog switch network 12 by lines 14a- 14d. A signal V2 is inputted to the in-phase input terminal 15, and the differential input signal of a signal V1 is inputted to the terminal 17. In this case, gain G is (R1+R2)/R1, where R1 is the value of resistance between the terminal 16 of the network 13 and the network 12 and R2 is the value of resistance from the network 12 to the output terminal 16 of the amplifier 11. Therefore, the network 12 is operated by a control signal to change connection points in the network 13, so a feedback resistance value varies accordingly to vary the gain of the amplifier 11. |
