| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a phase compensation synchronous detection circuit capable of always controlling the phases of a synchronized detection signal and a reference signal into a coincident state. <P>SOLUTION: A phase control oscillating signal of a frequency lower than that of the reference signal is input into a control terminal of a phase shift circuit, and periodic phase shift is applied to the reference signal input into the synchronous detection circuit. The periodic phase shift component is taken from the output side of the synchronous detection circuit, and the periodic phase shift component is synchronously detected by a synchronous detection circuit for phase difference detection using the phase control oscillation signal as the reference signal. When there is no phase difference between the synchronized detection signal and reference signal input into the synchronous detection circuit, the synchronous detection circuit for phase difference detection outputs an alternating signal including no direct current. When there is phase difference, it outputs a phase difference detection signal including positive or negative direct current component. The phase difference detection signal is integrated and is applied to the control terminal of the phase shift circuit, and the phase of the reference signal is shifted to be compensated so as to eliminate the phase difference between it and the synchronized detection signal. <P>COPYRIGHT: (C)2008,JPO&INPIT |
