Image Number 11 for United States Patent #7499819.
A flow measuring device has a sensor element for outputting a nonlinear signal according to a flow rate. In the device, a first signal processing system obtains a first signal by filtering the nonlinear signal output from the sensor element, thereafter corrects a sensitivity of the filtered signal. A second signal processing system obtains a second signal by linearizing the nonlinear signal from the sensor element, thereafter filters the linearized signal and corrects a sensitivity of the filtered signal, and then non-linearizes the linearized signal with a corrected sensitivity. An amplifier amplifies a differential signal between the first and second signals. A correcting section corrects the nonlinear signal by using the amplified differential signal.