School of Integrated Circuit Science and Engineering, University
of Electronic Science and Technology of China, Chengdu 611731, China
E-mail: liujiaxin@uestc.edu.cn
The kT/C cancellation technique can effectively reduce the DAC size for
SAR ADCs and thus relax the burden for input drivers and reference
buffers. However, the prior kT/C cancellation technique suffers from a
hard trade-off between the noise, amplifier bandwidth and linearity. In
this work, an improved kT/C noise cancellation technique is proposed to
break the trade-off. It uses presampling to hold the input signal
unchanged during the noise cancelling phase, leading to significantly
relaxed requirements on the bandwidth and linearity of the amplifier.
The proposed technique is verified in a 14-bit 200MS/s SAR ADC with the
DAC size of 128 fF. Simulation results show that this work achieves 75.6
dB SNDR and consumes 1.56 mW power.