Efficient 8X Oversampling Asynchronous Serial Data Recovery Using IDELAY Application Note (XAPP861) - Xilinx Virtex-4 and Virtex-5 devices a have high-precision programmable delay element associated with every input pin. These delay elements, called IDELAY, can be used to implement an oversampler that uses very few FPGA logic resources and, more importantly, just a single DCM and two global clock resources to do 8X oversampling. This solution provides better jitter tolerance than techniques that use multiple DCMs.