Patent ID: 8069009

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 sampling phase adjustment circuit configured to adjust the phase of a sampling clock having a predetermined sampling frequency; an analog-to-digital converter circuit configured to convert the sensor signal to a digital sensor signal in synchronization with the sampling clock phase-adjusted by the sampling phase adjustment circuit; and a detection circuit configured to detect the physical quantity based on the digital sensor signal from the analog-to-digital converter circuit, wherein the detection circuit includes 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 a reference clock having a frequency corresponding to the frequency of the sensor signal, and a multiplier circuit configured to multiply the digital sensor signal from the analog-to-digital converter circuit by the digital detection signal from the detection signal generator circuit, to detect a physical quantity signal corresponding to the physical quantity, and wherein the sampling phase adjustment circuit is configured to operate in synchronization with a multiplied clock having a frequency higher than the sampling frequency, to delay the sampling clock by a predetermined number of pulses of the multiplied clock.