Abstract
It is a low jitter clock circuit designing,it has introduced the pin function,internal configuration,electric charator,theory of operation,mode of operation,application circuit and pin package.The AD9540 is Analog Devices’ first dedicated clocking product specifically designed to support the extremely stringent clocking requirements of the highest performance data converters. The device features high performance PLL circuitry including a flexible 200MHz phase frequency detector and a digitally controlled charge pump current.The device also provides a low jitter,655MHz CML-mode, PECL-compliant output driver with programmable slew rates.External VCO rates up to 2.7GHz are supported. Extremely fine tuning resolution is another feature supported by this device.Information is loaded into the AD9540 via a serial I/O port that has a device write-speed of 25Mb/s.The AD9540 frequency divider block can also be programmed to support a spread spectrum mode of operation.
Key words: data conversion divider resolution PLL circuit charge pump VCO