Frequency Synthesizers’ Low Jitter Ease High-Speed Timing Issues

The MAX3671/MAX3673 are a pair of low-jitter frequency synthesizers with nine phase-aligned LVPECL outputs for high-speed systems. These devices use a low-noise VCO and PLL architecture to generate high-frequency (312.5-MHz), low-jitter (0.3 ps RMS) clock signals from a 62.5-MHz reference-clock input. Configured through a trio of four-level control inputs, the MAX3671 simultaneously generates two different frequencies for both Ethernet port clocking and MAC clocking, while the MAX3673 generates outputs for CPRI/UMTS reference clocking (122.88 MHz and 245.76 MHz). This capability eliminates the need for an costly high-frequency oscillator and a fanout buffer, thus saving board space and cost. The MAX3671 is suited for Ethernet interface applications such as enterprise switches and routers, and the MAX3673 is useful in wireless base stations that require CPRI reference clocking. The MAX3671/MAX3673 are fully specified over a temperature range of -45°C to +85°C and operate from 3.3 V, ±5%. They are available in a lead-free, 56-pin TQFN package. Prices start at $10.26 each in lots of 1000; evaluation kits are available to speed designs. MAXIM INTEGRATED PRODUCTS, Sunnyvale, CA. (800) 998-8800.