Integrated control circuit for adaptive sampling

A fully integrated controller for non-uniform data sampling suitable for the pre-processing of signals in a power- and size-restricted sensor front-end is presented. The sample rate is dynamically varied based on signal activity determined by the 2nd derivative of the input voltage. The derivative is realized with high-pass filters having 647 Hz cut-off frequency. A digital circuit generates the time-stamps and the trigger for an external analog-to-digital converter. Measured results of a 0.35 μm CMOS implementation show a sample rate variation of 7:1 and a system power advantage compared to conventional front-ends. The circuit dissipates 48 μW from ±1.5 V supplies and consumes an active area of 0.068 mm².