Low-power and low-noise fully differential difference amplifier for sub-nanoampere on-chip potentiostat

Abstract

In this paper, we present a low-power, low-noise and wide dynamic range biosensor for neurotransmitter detection that exhibits high sensitivity and linearity. The design uses a fully differential difference amplifier (FDDA) to decrease the number of amplifiers in the control part, with reduced overall power consumption as a result. Moreover, this amplifier provides an output voltage swing that is almost twice that obtained with single-ended amplifiers. Finally, the two differential pairs at the FDDA input eliminate the need for impedance isolation buffers and matching resistors, consequently reducing system noise for improved sensitivity and accuracy. Designing this biosensor in 180 nm technology led to a current sensitivity of 900 fA, an input-referred noise of 6.9 µVrms and a power consumption of 53.9 µW.