A 70 dB DR 10 b 0-to-80 MS/s Current-Integrating SAR ADC With Adaptive Dynamic Range

A charge-domain SAR ADC is presented which integrates the current of a variable-gain transconductor on its sampling capacitor, rather than being driven by a power hungry voltage buffer. The sampling circuit uses nonlinear MOS capacitors as sampling capacitor for passive amplification to relax the comparator noise requirements without compromising linearity. The prototype in 40 nm low power CMOS process consists of a 1.1-17.6 mS transconductor, combined with a 10 b 0-80 MS/s charge-sharing SAR ADC. It achieves 70 dB DR while consuming less than 5.45 mA from a 1.1 V supply and achieves a peak SNDR of 56.85 dB at 40 MS/s.