Hi,

I would like to know if there is a quick and cheap way of generating a clock 90 degree offset in phase from a given clock. I do not have a 2x faster clock which I may use to do this. The jitter on the shifted clock is not important, and the input has a 50% duty cycle.

Regards
Vivek

A couple of flavors to solve this:

A ring oscillator with multiple delay elements gets you all kinds of phases with respect to the input. Probably the most common solve used here.

Another approach:

LPF until you got a sinusoid
Create a V to I converter
Dump the I into a series RC
Differentially observe the V across the resistor
Differentially observe the V across the capacitor

90 degrees of phase difference, Voila!
Mind you, that one requires some items to support the operating voltage on the capacitor from not wandering away. However, that approach was used in peak detectors in disk drive read channels for a number of years.

Jerry