PLL102-03

Low Skew Output Buffer

47745 Fremont Blvd., Fremont, California 94538 Tel (510) 492-0990 Fax (510) 492-0991 www.phaselink.com Rev 02/23/06 Page 5

Output-Output Skew

REF

CLKOUT

The skew between CLKOUT and the CLK(1-4) outputs is not dynamically adjusted by the

PLL. Since CLKOUT is one of the inputs to the PLL, zero phase difference is maintained

from REF to CLKOUT. If all outputs are equally loaded, zero phase difference will

maintained from REF to all outputs.

If applications requiring zero output-output skew, all the outputs must equally loaded.

If the CLK(1-4) outputs are less loaded than CLKOUT, CLK(1-4) outputs will lead it; if the

CLK(0-4) is more loaded than CLKOUT, CLK(1-4) will lag the CLKOUT.

Since the CLKOUT and the CLK(1-4) outputs are identical, they all start at the same time,

but difference loads cause them to have different rise times and different times crossing

the measurement thresholds.

CLK(1-4)

Zero Delay

REF

CLKOUT

CLK(1-4)

Advanced

REF

CLKOUT

CLK(1-4)

Delayed

REF input and all outputs loaded equally

REF input and CLK(1-4) outputs loaded equally,

with CLK(1-4) less loaded than CLKOUT.

REF input and CLK(1-4) outputs loaded equally, with

CLK(1-4) more loaded than CLKOUT.