An automatic gain control (AGC) and D.C. offset correction method and apparatus for controlling signal power of a received RF signal within a dual mode quadrature receiver is disclosed herein. The AGC apparatus includes an adjustable gain amplifier (18). A quadrature downconverter (20) coupled to the amplifier (18) serves to translate the frequency of the output signal to a baseband frequency which is offset by a predetermined margin from D.C. Two high gain active lowpass filters (76 and 78) provide out-of-band signal rejection for the baseband signals. A D.C. feedthrough suppression loop supresses D.C. offsets produced by a downconverter (20) and the lowpass filters (76 and 78). The AGC apparatus also generates a received power signal based on the power of the output signal. A saturating integrator compares the received power signal to a reference signal and produces the gain control signal by integrating or by refraining from integration based on values of the reference, received power signal, and gain control signals.