carry chain delay differs a lot between two LEs in same LAB - carry chain delay differs a lot between two LEs in same LAB I implemented TDC based on carry chain in Cyclone IV. By measuring the bin size based on code density method, after lots of random test, the delay destribution varies a lot for each delay element in the carry chain. Especially, the delays for two dalay elements(logic element)next to each other in same LAB differ a lot (see the figure). My question is: why most carry signal 'falls' in the odd-indexed position? ths a lot! Replies: Re: carry chain delay differs a lot between two LEs in same LAB That is exactly what i want, thanks a lot Replies: Re: carry chain delay differs a lot between two LEs in same LAB Perhaps the below article may help clarify your questions. https://arxiv.org/ftp/arxiv/papers/1805/1805.12390.pdf