MAX3872: Choosing an Optimal Filter Capacitor for the MAX3872 Multi-Rate CDR


The MAX3872 is a clock and data recovery (CDR) with limiting amplifier IC, designed to operate at multiple data rates. It is intended for regenerator and receiver applications and contains a fully integrated phase-locked loop (PLL). The PLL is a second-order feedback system that requires an external capacitor for the loop filter. This capacitor is a significant factor in multi-rate designs because it determines the acquisition time and jitter peaking at a particular data rate. This design note is intended as a guide for choosing the optimal filter capacitor to minimize acquisition time, while meeting the jitter peaking specifications at all the data rates required for the application. Read full article.