A wind sensor with an integrated low-offset instrumentation amplifier

A wind sensor with on-chip interface electronics has been implemented in a standard CMOS process. The sensor consists of a heated chip that is cooled non-uniformly by the wind. The resulting temperature gradient is measured by on-chip thermopiles, and from this information both wind speed and direction are determined. An on-chip chopper amplifier boosts the thermopile signals before they are transported off-chip. When chopped at 1 kHz the input offset of this amplifier is less than 20 /spl mu/V. Thermal crosstalk between the on-chip circuitry and the sensor is negligible, since the power dissipated by the on-chip circuitry (1.5 mW) is much less than that used to heat the sensor (600 mW).