A 1–20-GHz All-Digital InP HBT Optical Wavelength Synthesis IC

An integrated circuit (IC) for heterodyne optical phase locking in a 1-20-GHz offset range is hereby reported. The IC, implemented in a 500-nm InP HBT process, contains an emitter coupled logic digital single-sideband mixer to provide phase locking at a ± 20-GHz offset frequency, and a wideband phase-frequency detector designed to provide loop acquisition up to ±40-GHz initial frequency offset. The all-digital IC design has phase-frequency detection gain independent of IC process parameters or optical signal levels, and provides a wide offset locking range. A 100-ps delay decreases the overall loop delay, making wideband loop filter design possible. In addition, a medium-scale high-frequency logic design methodology is presented and fully discussed.