A PTC‐Inspired Energy Reduction Technique for SAR ADCs Used in CMOS Image Sensor Readouts

ABSTRACT This paper presents a photon transfer curve‐supported switching‐energy reduction technique for the SAR ADCs used in CMOS image sensor readouts. Here, the energy consumptions of the capacitive DAC and the SAR logic are minimized using selective capacitance reduction supported by PTC‐inspired bit‐depth compression. When our proposed method is combined with the ‐based switching energy reduction technique, the peak and average energy consumptions of the DAC are reduced by 91.28% and 93.99%, respectively, compared to the conventional binary‐weighted capacitive DACs for a 10‐bit effective resolution. Compared to conventional ‐based DACs, our proposed ‐based DACs consume 51.86% less energy. Besides decreasing the DAC switching energy, our proposed technique ensures 51% reduction in the energy consumption of the SAR logic compared to conventional ‐based switching due to the reduction in the number of clock cycles needed for the data conversion and its associated switching. Similarly, our proposed approach with monotonic switching scheme results in 25% reduction in the energy consumption of a 10‐bit DAC following monotonic switching.