A 2.1/5.2-NEF/PEF Capacitively Coupled Instrumentation Amplifier with Fast - Settling for Biosensor

This paper presents a power-efficient and quickly-settled chopper-stabilized capacitively coupled instrumentation amplifier (CCIA) for neural recording applications. To achieve a relatively-low high-pass corner frequency while achieving fast-settling, a duty-cycled resistor (DCR) based very-large time constant (VLT) integrator is proposed. By stacking inverters and splitting the input capacitor network, the input stage of the CCIA achieves four-time current reuse, significantly improving the power-efficiency. A prototype in 180-nm CMOS technology has 2.2µV input-referred noise (IRN) with 5kHz bandwidth (BW) while consuming only 2.92µA current from a 1.2V supply, achieving a noise efficiency factor (NEF) of 2.1 and a power efficiency factor (PEF) of 5.2. Simulations show that it can settle within 10ms after powering on with a maximum electrode DC offset of 50 mV.