A novel architecture for current-feedback instrumentation amplifiers with rail-to-rail input range

This paper presents a fully-differential currentfeedback instrumentation amplifier with rail-to-rail input common-mode (CM) voltage range. Gm mismatches due to input CM variations have been reduced exploiting an original commonmodes equalization loop. Chopping modulation is adopted to improve the performances of the amplifier in terms of offset and low frequency noise, while the intrinsic low-pass transfer function of the amplifier is exploited for the reduction of the offset-ripple. A prototype has been designed using the UMC 0.18um MM/RF CMOS process. Simulations, performed with a supply voltage of 1.5 V, showed that a maximum relative gain error of nearly ±1.5 %, against rail-to-rail input CM voltage variations, can be achieved