A Floating Differential DAC Expands the Output Voltage Range for Electrochemical Measurements

To operate a variety of electrochemical sensors, a potentiostat requires a large output voltage range. In order to implement this with a fully integrated potentiostat, we expand the digital-to-analog converter’s (DAC) output voltage range by providing a floating reference voltage with a current mirror and two amplifiers in a negative feedback configuration. A segmented 16 bit resistor string (R-string) DAC uses the floating reference voltage to generate excitation signals within the supply voltage range. We show that our floating differential DAC supports an output voltage range from 0.32V to 2.61V when operated at a supply voltage of 3 V. Furthermore, the static and the dynamic performance of the DAC are maintained during output voltage range expansion. These properties suggest that our DAC is suitable for integration in an electrochemical measurement system.