Mixed capacitor switching scheme for SAR ADC with highest switching energy efficiency

Abstract

A high energy-efficiency mixed capacitor switching scheme is proposed for the successive approximation register (SAR) analogue-to-digital converter (ADC). The new switching scheme combines a new switching method, monotonic switching method and split-capacitor technique. The new switching method achieves no switching energy consumption until the fourth comparison, and the low-power monotonic switching method is utilised for the remaining comparisons. Moreover, fewer bit capacitors are needed at the same resolution because of the split-capacitor technique. The proposed method achievesa 99.4% reduction inswitching energy when compared with the conventional SAR architecture.