Switched Capacitor Analog Midrange Detector Circuit for 8 Voltage Inputs: Design Principles, Characterization and Performance Demonstration

Changing electrode potentials during electrochemical measurements requires dynamic positioning of the electrode's reference point at runtime. An analog implementation of a midrange detector circuit serves as the sense part to continuously adjust absolute electrode potentials. The midrange detector topology is based on a sourcefollower winner-take-all circuit and a switched capacitor mean creation. The topology allows simultaneous monitoring of 8 voltage input channels. The maximum error is 100 mV over the commercial temperature range of −20 • C to 70 • C which is equivalent to a 5 bit implementation with analog-to-digital converters (ADCs). With a maximum power consumption of 12.06 pW per decision at a sampling frequency of 1.5 MHz the topology is an efficient way to realize dynamic electrode positioning. The application demonstrates that analog computation when applied with care is resource efficient while still having good performance compared to the strategy of immediate analog-todigital conversion and digital signal processing. This statement is justified by the fact that only the pure analog conversions necessary to reach the specifications would require 12.6 pW with the best published ADCs at the moment.