Variable gain amplifier

Abstract

Abstract PURPOSE:To eliminate the influence of variance in the no-resistance of a switch by switching an input-side resistance and a negative feedback resistance through a switching means, and thus varying a gain. CONSTITUTION:A signal e<1> inputted to a terminal 1 is amplified by an amplifier 4 and outputted from a terminal 2. Switching means 8 and 9 are provided to the input side of the amplifier 4 and a negative feedback path. When the switching means 8 and 9 are closed, the resistance of the input side is R2+DELTAr1 (where DELTAr1 is the on-resistance of the switching mean 8) and the resistance of the negative feedback path is R1+DELTAr2 (DELTAr2 is the on-resistance of the switching means 9). When the switching means 8 and 9 are opened, on the other hand, the off-resistances are made sufficiently great by resistances R3 and R4, so they are disregarded. Forming the switching means in the same IC results in that r1=r2, and also equalizes temperature characteristics, so gain variation due to variance of the switching means is eliminated.

Inventors

• 👤 Tetsuya Kono
• 👤 哲也 河野
• 👤 Tetsuo Takeshita
• 👤 竹下　鉄夫
• 👤 Kazuo Hamasato
• 👤 和雄 浜里

Bibliographic Details