Patent ID: 6215989
Filing Date: 2001-04-10
Classification: H03G

Abstract:
A variable gain circuit comprising:a gain control signal correction circuit configured to correct a gain control signal Vx which varies linearly to a gain in decibel expression to obtain a corrected gain control signal Vy as follows:Vy=Vt.times.ln{exp (b.times.Vx/Vt)-1}where, Vt is a thermal voltage, and b.gtoreq.0; anda gain control circuit, configured to control a gain of an input signal according to the corrected gain control signal Vy, having a following gain:Ia/I.sub.sig =1/[1+exp (Vy/Vt)]where I.sub.sig is an input signal current, and Ia is an output signal current.