Hi,
For ADC Clk (becouse they need usual 50+/-5% duty) I would design with a "clock circuit", they has on chip PLL, some are "delay less" too...
You can find such ICs from National,fFairchild, nxp, Quality Semi, one (some older) examplar is: QS5V993A has 40 MHz from 10MHz in, you has 4x Outputs, with programmable phases...
If you likes/needs exactly 50% duty to produce (& dont become QS5V like ICs); a relative simple way is to make 80MHz & divide it by 2 (FF)= a garantied 50% pulse output
Good luck!
K.
Added after 10 minutes:
I learnd; Quality Semi is yet IDT...
w*w.qualitysemi.com/?app=search&searchType=parametric&catID=58697
i.e.:74FCT388915T