Patent ID: 8013647

Claim:
A physical quantity detection circuit used for a physical quantity sensor that outputs a sensor signal according to a physical quantity given externally, the circuit comprising: a first phase adjustment circuit configured to receive a reference clock having a frequency corresponding to the frequency of the sensor signal and operate in synchronization with a first operation clock having a frequency higher than the frequency of the reference clock, to delay a transition edge of the reference clock by a predetermined number of pulses of the first operation clock: and a detection circuit configured to detect a physical quantity signal corresponding to the physical quantity from the sensor signal using a transition edge of the reference clock delayed by the first phase adjustment circuit as the reference, wherein the first phase adjustment circuit includes a phase adjustment counter configured to start counting the number of generated pulses of the first operation clock in response to a transition edge of the reference clock and generate a timing signal once the number of generated pulses reaches a predetermined value, and the detection circuit includes an analog-to-digital converter circuit configured to convert the sensor signal to a digital sensor signal, a detection signal generator circuit configured to generate a digital detection signal corresponding to a sine wave signal in response to a transition edge of the timing signal generated by the phase adjustment counter, and a multiplier circuit configured to multiply the digital sensor signal obtained by the analog-to-digital converter circuit by the digital detection signal generated by the detection signal generator circuit, to detect the physical quantity signal.