A 1–20 GHz InP HBT phase-lock-loop IC for optical wavelength synthesis

We report a PLL IC for locking, at a controlled frequency offset between 1 and 20 GHz, the optical phase and optical frequency of a slave semiconductor laser to that of a reference semiconductor laser. The IC, implemented in a 500 nm InP HBT process, contains an ECL digital single-sideband mixer to provide phase-locking at a +/− 20 GHz offset frequency, and also contains a wideband phase-frequency detector to provide loop acquisition given up to +/−40 GHz initial frequency offset.