Precise delay generation using coupled oscillators

Precise delay generation is a necessity in state-of-the-art integrated test and measurement chips[ll. High time resolution is difficult to achieve. It requires precise delays significantly smaller than an intrinsic gate delay. Precise delays with gate-delay resolution can be achieved by phase locking a ring oscillator to an established clock. An array oscillator, a series of coupled ring oscillators, achieves a delay resolution equal to a buffer delay divided by the number of rings. Using a 2pm n-well CMOS technology, delays as small as 30ps are achieved a t frequencies up to 200MHz.