A 21.8b sub-100μHz 1/f corner 2.4μV-offset programmable-gain read-out IC for bridge measurement systems.

High-resolution read-out integrated circuits (ROICs) are often used in DC measurement systems such as bridge transducers. Since these typically output small-amplitude signals with a bandwidth of a few hertz, a highly linear gain ROIC is required with a resolution above 20b [1,2]. In previous work, high-precision instrumentation amplifiers (IAs) followed by analog-to-digital converters (ADCs) were reported [1-4]. However, IA topologies based on switched-capacitor (SC) or multiple operational amplifiers (opamps) suffer from a poor power-noise tradeoff due to noise folding [2], or the number of amplifiers [3], respectively. Current-feedback IAs (CFIAs) are more power-efficient, but require highly linear feedback resistors [4,5]. This drawback can be addressed by capacitively-coupled IAs (CCIAs), which are even more power efficient [1].