An Energy‐Efficient Switching Scheme for SAR ADCs With Unary‐Weighted Capacitor Array and Iterative Averaging Technique

ABSTRACT This paper proposes an efficient switching scheme for SAR ADCs based on a unary‐weighted capacitor array and an iterative averaging technique. By replacing the conventional binary‐weighted array with a unary‐weighted structure, the number of capacitors in the CDAC is significantly reduced. Moreover, a novel iterative averaging technique is employed, which redistributes charge among capacitors through charge presetting in the sampling phase and charge sharing in the conversion phase, introducing no additional switching power consumption or common‐mode variation in this process. For a 10‐bit ADC, the proposed switching scheme achieves an 87.4% area reduction and 100% switching energy saving compared to the conventional switching scheme. Furthermore, benefiting from the improved matching accuracy of the unary‐weighted capacitor array and the minimal charge disturbance per switching, the proposed scheme exhibits very low sensitivity to reference voltage variations and achieves excellent linearity.