The AD9540 is a 655MHz low jitter clock generator from ADI company. It has excellent intrinsic jitter performance, 25Mb/s write-speed serial I/O control, 200MHz phase frequency detector inputs, 655MHz programmable input dividers, programmable RF divider, 8 programmable internal clock rates, 93 fS resolution programmable edge delay, 1.8V power supply, 3.3V power supply, programmable charge pump current, multi-chip synchronization, dual-mode PLL lock detect and 655MHz CML mode PECL compliant driver.