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Complex Clocking Situations Using PrimeTime
Paul Zimmer
Cisco Systems
1450 North McDowell Blvd.
Abstract
The world of telecommunications chips is full of messy clocking situations. Muxed clocks are
the norm, and opposite edges and divided clocks abound. These can be difficult to describe to
PrimeTime. This paper will cover the tricks and techniques that the author has developed to
describe these complex clocking situations to PrimeTime so that the design will be properly
constrained and timed and avoid the need to pour over reams of timing reports looking for
problems.
Paul Zimmer
Cisco Systems
1450 North McDowell Blvd.
Abstract
The world of telecommunications chips is full of messy clocking situations. Muxed clocks are
the norm, and opposite edges and divided clocks abound. These can be difficult to describe to
PrimeTime. This paper will cover the tricks and techniques that the author has developed to
describe these complex clocking situations to PrimeTime so that the design will be properly
constrained and timed and avoid the need to pour over reams of timing reports looking for
problems.
