DVCC-based very low-offset current-mode instrumentation amplifier

This paper presents an alternative implementation of a chopper-modulated current-mode instrumentation amplifier. The structure provides very low-offset voltage at the output due to chopper modulation and residual offset removal path. The residual offset removal path is based on low-pass filtering using grounded capacitances which provides compact design structure compared to various chopper-modulated instrumentation amplifier designs. Rail-to-rail input common-mode range is possible due to transmission gate-based input chopper switching scheme. The design is made using a 0.35-mu m CMOS process with +/- 1.65V supply voltage. The area of the amplifier is 234 mu mx344 mu m, including all the filtering elements. The proposed circuit with residual offset removal path provides less than 1 mu V input referred offset voltage. The advantage of the proposed instrumentation amplifier is its large bandwidth, simple design scheme and compact area compared to chopper-modulated voltage mode amplifiers.