Self-calibrating closed-loop circuit for configurable constant voltage thermal anemometers

A new circuit is described which applies a configurable voltage across an RTD while the current flowing through it is measured with a current mirror. The circuit also allows working with voltages above the IC supply voltage to cope with the high power RTD dissipation normally required in thermal anemometers. The circuit is periodically calibrated to cancel the errors and amplifier offset and therefore improves measurement accuracy. Experimental measurements of the circuit fabricated using 0.35 μm AMS technology show the functionality and improved power efficiency.