A sub-1V CMOS Instrumentation Amplifier for an AFE Interfacing with Sensors

This paper presents the design of a low-noise capacitively-coupled instrumentation amplifier with a sub-1V power supply, which is suitable for low-power sensor data acquisition systems. This amplifier is part of an Analog Front-end (AFE) which is implemented in a standard 130nm bulk CMOS technology. Beside the high-impedance input amplifier, the AFE includes a programmable switch-capacitor bandpass filter and a sigma-delta modulator. A chopper modulation technique is implemented to further reduce the flicker noise, with a positive feedback network to compensate the resulting low input impedance. The preliminary post-layout simulated results of the instrumentation amplifier achieves a total power consumption of 2.6μW, with an open loop gain of 87dB and a GBW of 584kHz and with the input reffered noise of 4.6μVrms and a NEF value of 4. The maximum CMRR of the amplifier is 101dB and the PSRR minus is greater than 66dB. For a sub 1V power supply, the input frequency range is up to 10 kHz.