A 0.06mm2 14nV/√Hz chopper instrumentation amplifier with automatic differential-pair matching

A small-area low-power low-noise instrumentation amplifier (IA) is desired in arrayed sensor devices that are used for high-spatial-resolution biomedical and environment monitoring systems. This paper presents a 0.06mm
²
chopper-stabilized current-feedback IA with 13.5nV/√Hz input-referred noise and less than 3.5μV offset voltage. For significantly reducing the ripple due to chopping, the proposed IA uses a novel digital calibration scheme, namely, automatic differential-pair matching (ADPM), which enables a small die area and low-power operation. The proposed IA is implemented in a standard 0.18μm CMOS and achieves a noise efficiency factor (NEF) of 7.2 while drawing 194μA. The active area of the IA is 7.8× smaller than that of the state-of-the-art [1-5] while it maintains low output ripple, low noise, and low power.