A switched capacitor differential circuit switches first and second differential input signals (Vinp1, Vinp2) to respective inputs (A, B) of an operational amplifier (12) via respective first and second signal paths. Each signal path includes a coupling capacitor (13, 14) and two switching devices (2, 3 and 4, 5) to switch the input signals to charge the capacitors at a first phase of a clock signal and to discharge the capacitors onto the inputs of the amplifier at a second phase of the clock signal. In order to remove common mode spikes from transferring to the amplifier, a pair of comon mode capacitors (16, 17) are coupled between the inputs and a common node (15), which is coupled via a pair of switches (6, 7) to the first and second signal paths between the capacitors and the second of the switching devices so that the coupling capacitors are discharged relative to the common node.