The Design and Optimization of a 25 kS/s 10 bit Micropower Current S/H Cell for Weak Current Bio-medical Applications

In this paper, a micropower current sample-and-hold front-end is designed for weak current bio-medical applications in a 0.35-mum standard CMOS process. The design reduces the distortion of the current-mode sample-and-hold stage by exploiting the exponential I-V relationship of weakly-inverted MOS transistors. The design and optimization process for the stage is introduced in the paper. With the optimized design, SPICE simulation shows that the sample-and-hold stage can achieve over 60 dB SNDR at the sampling rate of 25 kS/s, with the input signal at the Nyquist frequency of 12.4 kHz. The input current range is 100 nA. The power consumption of the stage is about 3.6 muW.