Targeting ultra-low power consumption with non-uniform sampling and filtering

Today signal processing systems uniformly sample analog signals without taking advantage of their intrinsic properties. For instance, temperature, pressure, electrocardiograms, speech signals significantly vary only during short moments. The digitizing system does not take into account this specificity and furthermore is highly constrained by the Shannon theory which fixes the sampling frequency at least twice the input signal frequency bandwidth. It has been proved that Analog-to-digital Converters (ADCs) using a non equi-repartition in time of samples leads to interesting power savings compared to Nyquist ADCs. A new class of ADCs called A-ADCs (for Asynchronous ADCs) based on level-crossing sampling (which produces non-uniform samples in time) and asynchronous technology has been developed. This article will present a fully non-uniform filtering technique associated to such an ADC which is able to drastically reduce the power consumption.