A programmable full clock rectifier and sample-and-hold amplifier for biomedical applications

Post-layout Monte Carlo analysis and characterization as function of temperature, process, and mismatch variations of a rail-to-rail full clock fully programmable differential rectifier and sample-and-hold amplifier (RSHA) for biomedical applications are presented in this paper. The RSHA is based on a class AB fully differential two-stage operational amplifier. It uses the Miller compensation capacitor to hold the output and a duplicate of the output stage to ensure proper offset cancellation and common-mode control. The circuit is designed and implemented using a 0.35 μm CMOS technology. Results show that the total harmonic distortion, for an almost rail-to-rail input swing at 10 kHz and at 100 kS/s is equivalent to more than 9 bits in worst case. The dc output offset is below 140 μV and the error introduced by the rectification with respect to the non rectified signal is less than −100 dB. The power consumption is 3 mW with ±1.25 V supplies. The RSHA provides an output valid for more than 85% of the clock cycle.