A 2.1 μW area-efficient capacitively-coupled chopper instrumentation amplifier for ECG applications in 65 nm CMOS

This paper describes a capacitively-coupled chopper instrumentation amplifier for use in electrocardiography (ECG). The amplifier´s gain is accurately defined by a capacitive feedback network, while a DC servo loop rejects the DC offset generated by the electrode-tissue interface. The high-pass corner frequency established by the servo loop is realized by an area-efficient switched-capacitor integrator. Additional feedback loops are employed to boost the amplifier´s input-impedance to 80 MΩ and to suppress the chopper ripple. Implemented in a 65 nm CMOS technology, the amplifier draws 2.1 μA from a 1 V supply and occupies 0.2 mm².