Thanks BradtheRad for the reply.
What I want to design is a delay circuit that delays the incoming signal by 3/4 and 1/2. For example lets say that the incoming signal is 100 mbps and the delay circuit should delay the signal by 1/2 and 3/4 i.e. 5 ns and 7.5 ns respectively.
Does the solution that you have provided for 3/4 delay works for delaying the signal by 1/2 also by adjusting the potentiometer?
Thanks a lot!
If you play with the values then you should be able to get delays anywhere on the pulse period.
However the 555 will not operate as fast as 100 MHz. You'll need to find a different one-shot (monostable multivibrator). It may be necessary to build one from discrete (and fast) devices.
My schematic illustrates the concepts at work (if you wish to experiment):
1) Apply the pulse to a capacitor, to give you a ramp wave. (Invert the pulse first, if need be.)
2) Adjust a comparator to trigger at a certain point on the ramp wave. (The input stage in the 555.)
3) The comparator output goes high for a time that you set, then goes low.
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Another concept is to make a schmitt trigger. You do this by adding a hysteresis loop to the comparator. Then it will trigger at a high point on the triangle wave, and then trigger at a low point. This is a tricky adjustment to get right.
There are schmitt triggers packaged in IC form, which are sufficiently fast for your purposes.