A microphone circuit has a clip detection circuit (30) which detects when an analogue to digital converter (ADC, 12) output has reached a threshold. A variable capacitance (34a, 34b, 34c, 34d), which functions as a variable input load associated with the microphone (11), is controlled based on the clip detection circuit output, the feedback is thus based on the ADC out-put level, and the processing of this signal can be implemented without requiring baseband processing of the signal—it can simply be based on a state of the ADC output.