Patent ID: 7162029

Claim:
A gain controller, comprising: an input terminal for receiving a time-varying input signal; another input terminal for receiving a digital gain control signal; a modified R2R ladder network coupled to the input terminal for receiving the time-varying input signal and to the another input terminal for receiving the digital gain control signal; a mixer coupled to the modified R2R ladder network wherein the mixer produces an output signal, which is the time-varying input signal scaled by a gain factor, and the mixer performs a current-to-voltage conversion; and wherein the modified R2R ladder network further comprises: resistors for R2R branches of the modified R2R ladder network; switches coupled to the R2R branches; and a switch controller for controlling the switches in conformity with the digital gain control signal; and wherein the mixer further comprises: an operational amplifier having one input coupled to a common mode voltage and an output that provides the output signal; and a feedback resistor having one end coupled to another input of the operational amplifier and another end coupled to the output of the operational amplifier; and wherein an output of the modified R2R ladder network is a current fed into the feedback resistor and the another input of the operational amplifier.