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Clock Deglitcher using Post Integration

IP.com Disclosure Number: IPCOM000117400D
Original Publication Date: 1996-Feb-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Benayoun, A: AUTHOR [+4]

Abstract

Disclosed is a method to improve the clock stability to avoid erroneous sampling due to external EMC, ESD, crosstalk or bad contacts. The oversampling method is generally used to overcome this problem on data but cannot be applied to very high speed clock. The idea is to analyze five continuous clock state samplings.

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Clock Deglitcher using Post Integration

      Disclosed is a method to improve the clock stability to
avoid erroneous sampling due to external EMC, ESD, crosstalk or bad
contacts.  The oversampling method is generally used to overcome this
problem on data but cannot be applied to very high speed clock.  The
idea is to analyze five continuous clock state samplings.

The advantages of the current solution are the following:
  o  Optimized for any kind of non repetitive error
  o  Suitable for very high speed clocks

Applications of the invention:
  o  All communication lines except very high speed lines where other
      methods will be less expensive.

      The described mechanism allows to deglitch and replace any
missing state on any kind of continuous clock, even high speed clock
as no oversampling needs to be performed.

      An input clock INPUT is clocked by CLK2:  clock having twice
the frequency of the input clock.

      CLOCK1 is the result of the sampling of INPUT by CLK2.

      CLK2 is the INPUT clock doubled to start the mechanism and
becomes the CLOCKOUT clock doubled when the system is stabilized:
after detection of some transitions on CLOCKOUT.  This may be
achieved by a counter started by CLOCKOUT which will change thanks to
a selector the input clock of the clock doubler on the flight.
Similarly, when CLOCKOUT disappears, a counter will reset the above
mentioned selector to the initial input.

      -CLOCK1 (inverted...