Elimination of DC offset in analog baseband circuit with minimized transients

摘要

An analog baseband circuit includes first and second DC (direct current) offset cancellers and an offset canceller controller. The first DC offset canceller includes a first filter and a first PGA (programmable gain amplifier) with a first gain step for eliminating a first dc component from an input baseband signal. The second DC offset canceller includes a second filter and a second PGA with a second gain step less than the first gain step for eliminating a second dc component from an output of the first DC offset canceller. The offset canceller controller controls the first and second filters to operate in a fast mode when a gain of the first PGA is changed.