An Adaptive Resolution Asynchronous ADC Architecture for Data Compression in Energy Constrained Sensing Applications

An adaptive resolution (AR) asynchronous analog-to-digital converter (ADC) architecture is presented. Data compression is achieved by the inherent signal dependent sampling rate of the asynchronous architecture. An AR algorithm automatically varies the ADC quantizer resolution based on the rate of change of the input. This overcomes the trade-off between dynamic range and input bandwidth typically seen in asynchronous ADCs. A prototype ADC fabricated in a 0.18 μm CMOS technology, and utilizing the subthreshold region of operation, achieves an equivalent maximum sampling rate of 50 kS/s, an SNDR of 43.2 dB, and consumes 25 μW from a 0.7 V supply. The ADC is also shown to provide data compression for accelerometer applications as a proof of concept demonstration.