PURPOSE: To exercise control over the absolute gain either to increase or decrease freely by amplifying once the reference voltage and then controlling it to have a required value by trimming.
CONSTITUTION: The reference voltage V1 is amplified by an amplifier 1, and the voltage V2 is produced. The level of the V2 is decided by resistance R1 and R2 and divided by the resistances R3 and R4 of a trimming circuit 2 to be delivered via a buffer amplifier 3. The output voltage V4 of the amplifier 3 can be set either larger or smaller than the voltage V1 since the voltage V2 is larger than the V1. Therefore the absolute gain can be increased or decreased by using the voltage V4 as the reference voltage of either an A/D converter or a D/A converter.
ITOU AKIHIKO
YAMAMURA TAKESHI
KONDOU HIROSHI
HAGA AKIRA
