NRZ timing recovery technique for band-limited channels

Nonreturn-to-zero (NRZ) data, when transmitted over band-limited channels, suffer from the lack of zero crossings because the elongated tail of each pulse interferes with subsequent ones, causing intersymbol interference (ISI). An NRZ timing recovery technique working with a decision-feedback equalizer (DFE) recovers the clock from the equalized waveform and enables data transmission at a rate ten times higher than the channel bandwidth. The proposed timing recovery technique uses a data-triggered low-jitter phase detector to sustain phase locking even with 600 missing transitions, A data rate of 30 Mb/s in 3-MHz bandwidth is demonstrated with a peak-peak clock jitter of 2 ns using 2-μm CMOS