Abstract: A switched- capacitor summer 400 includes an operational amplifier 206 having an input and an output, first and second parallel capacitors 307, 401, first switching circuitry 308, 404 and second switching circuitry 402, 403. First switching circuitry 308, 404 discharges first capacitor 307 during a first timing phase and couples second capacitor 401 between the input and the output of operational amplifier 306 during a first timing phase. Second switching circuitry 402, 403 couples a first capacitor 307 between the input and output of operational amplifier 306 during the second phase to transfer charge from capacitor CS to capacitor 307 and charge up capacitor CH during the second phase.