| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a parallel type four-phase phase control circuit capable of always keeping a phase difference π/2 in an orthogonal phase control part constant, thereby evading the occurrenve of receiving sensitivity penalty caused by a phase shift. <P>SOLUTION: The four-phase phase control circuit branches a part of an output optical signal of an optical coupling part, receiving the branched optical signal for a monitor and converting it into an electric signal, and detecting an AC component of power of the converted electric signal, and controls the phase of the orthogonal phase control part so that this power is minimized. <P>COPYRIGHT: (C)2007,JPO&INPIT |
