Bit-rate transparent electronic data regeneration in repeaters for high speed lightwave communication systems

Two types of system are subject to resynchronization in direct data transmitting communication links: 1/ Bit-rate invariant systems: where the bit-rate of the system is predefined and the only variation of the data rate is due to unwarranted effects originating from local oscillator drift on the transmitter side, temperature effects, influence of the surrounding, etc. 2/ Bit-rate variant systems: where the bit-rate of the systems is not predefined and may vary dynamically during operation. The system is then operating as a super-set of the bit-rate invariant system. The ultimate structure is then a bit-rate transparent system. The latter has been investigated in this paper. Two approaches are presented for realization of bit-rate transparent data regeneration: locked oscillator, phase-locking structures (partially bitrate transparent); freerunning (unlocked) oscillator, sampling structures (fully bitrate transparent). Both approaches are suitable for single chip integration and for bit-rates up to 10 Gb/s, however, the performance is a trade off between acceptable bit-rate variation range and jitter constraints on the regenerated data. The latter may be translated as the phase/frequency jitter on the internally recovered retiming signal (i.e. clock)