I've got an application where I need to measure the relative timing between edges of a couple input signals, with a precision of 5 ns or less. For example, I want to know the time (number of clocks) between the rising edge of signal A and the rising edge of signal B. I'm doing it with an FPGA now, but it would be great if I could use a timer in a microprocessor or something similar. I haven't seen any timers that can run that fast, although I haven't done an exhaustive search. Can anyone recommend a micro that can do the job? Is there something that can even get close, say with a precision under 10 ns?
I should also mention that I'd like the parts cost to be under $10 in quantity.
Thank you and please let me know if you need some more information.