| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a physical quantity sensor for enlarging a frequency detection range by making frequency-voltage characteristics linear. Ž<P>SOLUTION: The physical quantity sensor 1 includes: an oscillation circuit 30 for outputting an oscillation signal O1; an oscillation circuit 40 for outputting an oscillation signal O2; a phase comparator 50 for outputting a phase difference signal (a) wherein phases of O1 and O2 are compared with each other; a loop filter 60 for outputting a filter signal b from the phase difference signal (a); a differentiation circuit 70 for outputting a differential signal c from the filter signal b; a phase delay determination part 80 for outputting a determination signal d as to whether or not the phase of O2 advances from the phase of O1; a comparator 100 for outputting a comparison signal e for determining whether or not voltage of the differential signal c is larger than predetermined voltage Vref; an exclusive-OR circuit 110 for outputting a control signal f wherein the determination signal d and the comparison signal e are exclusive-ORed; a differential amplitude circuit 120 for outputting a differential amplitude signal g wherein the differential signal c and power supply potential Vcc are differentially amplified; and a selection circuit 130 for outputting one of the differential signal c and the differential amplitude signal g based on the control signal f. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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