Browse Prior Art Database

Method for Analyzing Timing On a Multi-Frequency Chip

IP.com Disclosure Number: IPCOM000101042D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Chapman, RJ: AUTHOR

Abstract

When logic based on one frequency entirely surrounds logic that is on a different frequency and the surrounded logic signals cross the boundary to communicate with logic on the same frequency, excluding the logic to perform timing analysis is difficult.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 73% of the total text.

Method for Analyzing Timing On a Multi-Frequency Chip

       When logic based on one frequency entirely surrounds
logic that is on a different frequency and the surrounded logic
signals cross the boundary to communicate with logic on the same
frequency, excluding the logic to perform timing analysis is
difficult.

      Generally, logic is divided up so that a part of logic
operating on one frequency is separated from logic operating on
another frequency, either on separate chips or parts of a chip.  See
the figure for an illustration of such a situation on a single chip.
If it is necessary to have a portion of logic running at one
frequency (Section C in the figure) completely surrounded by logic
operating at another frequency (Section B in the figure) and it must
communicate across this surrounding logic with yet another part of
logic running at its same frequency difficulty is increased when the
logic is generated using the Logic Synthesis System (LSS) where
logical "macros" are stitched together with connecting blocks (blocks
labelled "PA81" in the figure).

      The normal procedure is to exclude all logic associated with
one frequency while analyzing the logic on the other frequency.  This
is not appropriate in the situation described above.  For example, if
all of the logic in section B were excluded to analyze the logic in
sections A and C (since they are on the same time base and
communicate with each other they should be analyzed together) the
con...