A 36V voltage-to-current converter with dynamic element matching and auto-calibration for AC ripple reduction

A 36V precision voltage-to-current converter for 0-24mA loops is presented. It utilizes dynamic element matching (DEM) and an auto-calibration technique to achieve low DC inaccuracy (0.2%) and low DEM ripple (0.007%). Measurement results show that the auto-calibration suppresses the DEM ripple by a factor of 14, thus eliminating the need for a bulky off-chip ripple-suppression filter. The prototype chip is implemented in a 0.35μm CMOS process occupying 0.84mm². It has a quiescent current of 0.5mA and a rise time of 10.2μs for a 1mA-23mA output step.