A smart wind sensor using thermal sigma-delta modulation techniques

A smart wind sensor realized in a standard CMOS process combines a two-dimensional thermal flow sensor and three auto-zeroed comparators on a single chip. The comparators form the basis of three thermal sigma-delta modulators that control and digitize the heat distribution in the chip. One modulator maintains the chip at a constant temperature above that of the flow, while the other two cancel orthogonal components of a flow-induced temperature gradient. The bit-stream outputs of the modulators are decimated off-chip and used to determine wind speed and direction. Wind tunnel tests show that the sensor is capable of measuring wind speed and direction with an accuracy of +/-4% and +/-2degrees, respectively, over the range 2-18 m/s. (C) 2002 Elsevier Science B.V. All rights reserved.