A 12-bit 100-MS/s 83 dB SFDR SAR ADC with sampling switch linearity enhanced technique

Abstract

A 12-bit 100-MS/s 83 dB SFDR SAR ADC with sampling switch linearity enhanced technique is proposed. With the variation of input signals, the parasitic capacitance variation of sampling switch is reduced and the total parasitic capacitance is also depressed. Moreover, with substrate boost technique, the on-impedance of sampling switch would decrease. To demonstrate the proposed technique, a design of 12-bit 100-MS/s SAR ADC is fabricated in 40-nm CMOS technology, consuming 2 mW from 1 V power supply with a SNDR >65 dB and SFDR >83 dB. The proposed ADC core occupies an active area of 0.02 mm², and the corresponding FoM is 13.8 fJ/conversion-step with Nyquist frequency.