8-bit Controller for a DEM-based INAMP

The Dynamic Element Matching (DEM) based instrumentation amplifier relies on a digital controller to generate multiple signal paths between the nodes of a resistor network to decrease the gain error through averaging. In this paper, we assess the feasibility of combining the appealing DEM, i.e., very accurate resistive ratios ranging between 1 and 15, with the associated versatile and scalable digital controller. In the evaluation we performed a comparison in terms of footprint, gain accuracy and power consumption, against commercial precission amplifiers, while focusing on the design of the digital controller and additional circuitry implemented in a commercial 180nm technology. The gain precision of a typical amplifier is improved by more than 1800 times, with the error converging to as low as 10s of ppm, for gaussian mismatch distribution between -1% and 1% with the cost of DEM digital circuitry which adds about 30000 sq. microns of chip area which will consume $194\mu A$.