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Method for Multiple Glitch-Free Clock Selection

IP.com Disclosure Number: IPCOM000057069D
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-14

Publishing Venue

IBM

Related People

Authors:
Buckland, PA Dillinger, JR Hoffman, RD Hurlimann, DE [+details]

Abstract

Many electronic circuits require different clock sources at various times without causing any glitches on the clock output. A method is described to switch between these clock sources with a minimal amount of circuitry. The main problem is that glitches occur upon switching from one clock source to another, causing the target circuitry to go into an indeterminate state, resulting in improper operation of the logic. The method of switching between asynchronous clock sources without causing glitches on the output clock is done with a minimal amount of circuitry because of the uniqueness of the clock selection circuitry. (Image Omitted) Fig. 1 shows the block diagram of the clock. The clock selection circuitry is shown in Fig. 2.