In a radio circuit (299) that forwards a signal pair (I, Q) by a first channel (291, I) and by a second channel (292, Q), a gain controller (200) monitors differences between the overall gains (G1, GQ) in the channels and corrects a gain imbalance by feeding back a gain determining control signal (W) to one of the channels. The controller has first (221-224) and second (211-214) pluralities of single-bit comparators, operating at a high sampling rate, to monitor the signal pair at the channel inputs (281, 282) and at the channel outputs (283, 284), respectively, and to provide difference signals (DELTA X, DELTA Y) to an integrator (280) that calculates the gain control signal (W) at a decimated sampling rate (FR). |