17.5 A 0.07mm2 2-channel instrumentation amplifier with 0.1% gain matching in 0.16μm CMOS

Extremely small-area sensor front-ends are required for cost-constrained automotive applications. Instrumentation amplifiers (IA) for such front-ends must process multi-channel sensor outputs and provide gain matching over the channels for proper sensor operation. Angular sensors are a typical example, in which the sine and cosine outputs of a resistive magnetic sensor must be processed with adequate gain matching to avoid unacceptable angular errors. This paper presents a 2-channel instrumentation amplifier in 0.16μm CMOS with 0.1% gain matching and occupying 0.035mm² per channel. This represents a 13.3× area improvement with respect to state-of-the-art designs with similar gain accuracy [1]-[4], while maintaining low noise (18.7nV/√Hz), low offset (17μV) and high power efficiency (NEF=12.9). The accurate gain matching in a limited area is enabled by the adoption of a dynamic element matching (DEM) scheme and by the use of a high chopping frequency.