A Low-Noise Instrumentation Amplifier For Sensors Using A Noise-Efficient 0.2V-Supply Input Stage

In low-bandwidth, low-noise applications of wireless sensor nodes, the sensor front-end amplifier presents a power consumption bottleneck since its current draw is noise-limited and cannot be scaled with the low data rate, as is possible with the DSP and RF blocks. Prior work to improve the energy-efficiency of low-noise instrumentation amplifiers (LNIAs) for sensors includes chopper IAs, inverter-based LNAs, current-reuse through amplifier stacking, and low supply voltage amplifier design reaching 0.45V. This work presents an analog front-end (AFE) that achieves an Power Efficiency Figure (PEF) of 1.6 by using a chopper LNIA with a 0.2V-supply inverter-based input stage followed by a 0.8V-supply folded-cascode common-source (FCCS) stage. The high input-stage current needed to reduce the input-referred noise is drawn from the 0.2V supply, significantly reducing power consumption. The 0.8V stage provides high gain and signal swing, improving linearity.