A 0.32 µW, 76.8 dB SNDR Programmable Gain Instrumentation Amplifier for Bio-Potential Signal Processing Applications

In this paper, a novel ultra-low power, programmable gain instrumentation amplifier (PG-IA) for biomedical signal processing applications is presented. The fully differential PG-IA employs a new rail-to-rail current mirror input pair with three stage indirect compensation (RR-CMI) amplifier. The proposed design improves the dc offset by implementing a fully symmetrical structure and is further reduced by using one time calibration after power up. The accuracy of the common mode feedback circuit in the design is analyzed by implementing the same on both p-side and n-side loads. Power consumption is reduced by operating the fully differential amplifier on 1 V supply and calibration & digital logic on 0.5 V supply voltage, generated from internal ultra-low power voltage regulator. The design is integrated with complete analog front end (AFE) system and performance parameters are compared with the recent state of the art designs. The overall PG-IA design is implemented in standard 180nm CMOS technology. Simulation results show the power consumption to be 0.32 µW at 1 V supply, input referred noise of 0.72 µVrms integrated over frequency range of 1 Hz – 1 KHz, SNDR of 76.8 dB, PSRR of 119 dB, CMRR of > 100 dB. The design occupies a die core area of 0.0625 mm2.