David A Hedges

US Patent:

52045595, Apr 20, 1993

Filed:

Jan 23, 1991

Appl. No.:

7/645981

Inventors:

Ira Deyhimy - Thousand Oaks CA
Robert N. Deming - Thousand Oaks CA
William C. Terrell - Thousand Oaks CA
David W. Hedges - Sunnyvale CA

Assignee:

Vitesse Semiconductor Corporation - Camarillo CA

International Classification:

H03K 1900
H03K 513

US Classification:

307480

Abstract:

A circuit for controlling clock skew has a plurality of delay elements placed in each of the clock output paths in a clock distribution circuit. The delay elements may be selectively switched into or out of each clock output path in order to adjust the delays of each clock output path so that the skew between clock outputs is minimized. The delay in each clock output path is determined by measuring the frequency of a ring oscillator created by connecting a feedback loop across the delay elements. The frequency of oscillation is measured as delay elements are switched into or out of each clock output path until the frequency reaches close to a target frequency.