There is a link to a delay line conponent it the 3rd posting of this thread. In my honest opinion I think the delay line is the most reliable way to attain a suitable delay that is repeatable. I would not use an R/C delay in a production product nor would I use a string of 6 inverters as Kai talked about. The variation of delays that either of the solutions gives, over a wide range of manufactured products, is bound to result in some products failing to meet the worst case timing. When working out design problems where it is necessary to play games such as moving the edges of control pulses around it is mandatory to perform a full worst case timing analysis and ensure that the design works for all timing combinations between minimum and maximum. (It can be problematic doing this full analysis because often the minimum propagation delays are not given in the data sheets, I will generally analyze these cases with min values that are 1/3 the max spec. Thus if a data sheet calls out a gate prop delay of 18 nsec, but no min value, then I will use 6 nsec as the minimum.

To some this may seem severe to analyze in this manner, but if you intend to make products that will see large scale production across many fabrication lots of the the components used inside the product then this is well worth the effort. You will almost always find that this also adds some cost to the product as well because of additional or higher performance components are selected to ensure the timing design.

Michael Karas