Delta-Measurement Low-Power SAR ADC Architecture with Adaptive Threshold-First Switching

A delta-measurement successive approximation register (SAR) analog-to-digital converter (ADC) architecture with adaptive threshold-first switching scheme is designed to achieve low power for biomedical signals. Delta-measurement architecture achieves the delta voltage from the current sample to the last one with few the least weighted capacitors switched when the input signal changes slowly. Adaptive threshold-first switching scheme is utilized to decrease the number of successive approximation (SA) cycles. Analysis demonstrates the proposed delta-measurement architecture will not introduce nonlinearity. Simulation results show that this work can decrease the number of SA cycles, and can save more than 90% switching energy than the most effective LSB-first switching scheme when dealing with slowly-changing signal.