Optimizing Pulse Shaping for Baseband Digital Transmission with Self-Bit Synchronization

An effort is made to devise pulse shaping methods for self-bit-synchronizing systems that minimize both intersymbol interference and pattern-dependent jitter. Attention is confined to minimum-phase shaping which is considered from the standpoint of baseband applications. A short review of jitter analyses is also provided. It lays stress on discerning jitter components that accumulate along repeater chains from those that do not. Pulse shaping functions for the signal path, i.e., Nyquist's problem under minimum-phase constraint, are investigated first and found to result in Bessel filtering as well as its steepest descent modifications. It is observed that reducing intersymbol interference leads to increased pattern-dependent jitter. Next, pulse shaping functions for the timing path are developed. A broad sense symmetrical waveform concept produces a method of synthesizing shaping networks that can drastically reduce waveform dependent jitter, at the sacrifice of increased intersymbol interference. Finally, simultaneous minimizations of intersymbol interference and timing jitter are attempted. A minimal oscillatory tail shaping method incorporating a predistortion technique is shown to be quite efficient for this purpose and thus attractive for simple implementations.