A precision low-power mismatch-compensated sample-and-hold circuit for biomedical applications

This paper presents a new micro-power precision sample-and-hold (S/H) circuit for biomedical applications. In conjunction of low-power op-amp circuit design, the switched-capacitor capacitive-reset gain circuit with capacitor-mismatch compensation technique has been used. With this combination, the S/H has features of insensitive to capacitor mismatch, offset, and finite open-loop gain of op-amp whilst offering rail-to-rail characteristic. Operating at 1.8 V supply, the S/H circuit consumes 6.69 μA for low power design. At a sampling frequency of 128 kHz and in response to 1-Vpp and 1-kHz sinusoidal input, the S/H circuit has achieved less than 0.081 mV of hold-pedestal , -75.96 dB of total harmonic distortion (equivalent to 12.62 bits of ENOB) and 8.30 × 10^-3 μA/MHz of Figure of Merit (FOM).