Patent ID: 8482275

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 PLL circuit configured to generate a plurality of oscillated clocks having different phases; a selector configured to select one of the plurality of oscillated clocks generated by the PLL circuit; and a detection circuit configured to detect a physical quantity signal corresponding to the physical quantity from the sensor signal based on the oscillated clock selected by the selector, wherein the PLL circuit includes: an oscillation circuit including a plurality of delay elements connected in a loop, configured to output the outputs of the plurality of delay elements as the plurality of oscillated clocks, a low-pass filter configured to generate a control voltage for controlling the delay time of the plurality of delay elements, a frequency divider configured to divide the frequency of one of the plurality of oscillated clocks to generate a divided clock, a phase detection circuit configured to detect a phase difference between a reference clock corresponding to the sensor signal and the divided clock, and a charge pump configured to increase/decrease the control voltage based on the phase difference detected by the phase detection circuit, and wherein the detection circuit includes: a frequency division circuit configured to divide the frequency of the oscillated clock selected by the selector, to generate an analog detection signal, and a sync detection circuit configured to detect the physical quantity signal from the sensor signal using the analog detection signal generated by the frequency division circuit.