A smart wind sensor using time-multiplexed thermal Σ Δ modulators

A smart wind-sensor has been implemented in a standard CMOS process. It consists of a two-dimensional thermal flow-sensor that has been integrated with interface electronics. Two thermal ΣΔ modulators are used to cancel flow-induced temperature differences in the sensor. After decimation, their outputs are used to determine wind speed and direction. A third modulator maintains the sensor at a constant temperature above that of the flow. The operation of the various modulators is decoupled by operating them in a time-multiplexed manner. Wind tunnel tests show that the sensor is capable of measuring wind-speed and direction with accuracies of ±5% and ±3° respectively in the range 1 to 25m/s.