An offset compensation method with low residual drift for integrated thermal flow sensors

A new offset compensation approach for integrated
thermal flow meters is described. The method is based on micromachined
differential flow sensing structures with the heater split
into two identical and symmetrical sections. The power unbalance
between the two heaters is used to compensate the intrinsic sensor
offset. The effectiveness of the approach is proven by means of experiments
performed on micro flow meters fabricated by postprocessing
chips produced with a commercial microelectronic process.
The tests were devoted to demonstrate the robustness of the offset
compensation with respect to variation of both the gas temperature
and type.