Micropower high-performance SC building block for integrated low-level signal processing

A switched-capacitor instrumentation amplifier which uses correlated-double sampling to reduce the amplifier offset is discussed. Additional offset caused by clock-related charge injection is cancelled by a symmetrical differential circuit topology and a three-phase clocking scheme. An experimental low-power test cell has been integrated, showing 100 μV equivalent offset voltage and input noise equal to 270 μV. For a fixed gain equal to 10- and 9-kHz sampling frequency, the power dissipation is 36 μW (power supply: 5 V); the circuit measures only 0.2 mm/SUP 2/.