A New Phase-Locked Oscillator Adaptable to Input Signals with Periodical Phase Jumps

A new polyphase phase-locked oscillator (P-PLO) is proposed which overcomes one of the greatest difficulties in the passive bus configuration: timing extraction from signals in multiplexed channels with different mean phases. The proposed oscillator generates appropriate retiming clock pulses for each channel independent of other channels. Moreover, since pulse overlaps between channels may appear at the first and last bits of each channel, the oscillator shifts retiming clock phases of these bits to avoid sampling overlaps. A performance analysis method extended from the conventional Markov chain model is also proposed. The theoretically obtained jitter and retiming margin characteristics correspond closely to experimental results. This circuit is also shown to be adaptable to point-to-point configurations which, like passive bus, will be used in the ISDN basic interface recommended as one of the 1-series interfaces by CCITT. This allows easy rearrangement of interface wiring, e.g., changing from the passive bus to point-to-point configuration, without any adjustment of the network terminator.