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METHOD FOR INCREASING MAXIMUM NUMBER OF PORTS IN AN I/O MACRO

IP.com Disclosure Number: IPCOM000005931D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2001-Nov-16
Document File: 2 page(s) / 96K

Publishing Venue

Motorola

Related People

Barbara O'Neil: AUTHOR

Abstract

Using a grid router to route a gate array requires that all macro ports (connection points) fall on a grid point. In the case of l/O macros on the periphery of the array (fig. 1) this requires that the ports fall on a common multiple of the x and y grid increments. For Mosaic III the horizontal pitch is 6.0 urn and the vertical pitch is 4.5 urn. (fig. 2). This requires the ports to be on an 18 urn pitch.

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MOTOROLA Technical Developments Volume 10 March 1990

METHOD FOR INCREASING MAXIMUM NUMBER OF PORTS IN AN l/O MACRO

by Barbara O'Neil

   Using a grid router to route a gate array requires that all macro ports (connection points) fall on a grid point. In the case of l/O macros on the periphery of the array (fig. 1) this requires that the ports fall on a common multiple of the x and y grid increments. For Mosaic III the horizontal pitch is 6.0 urn and the vertical pitch is 4.5 urn. (fig. 2). This requires the ports to be on an 18 urn pitch.

   On Mosaic Ill ETI arrays the pad pitch is 4 mils. lb maximize the number of chip l/O while minimizing die size the l/O buffer macro must also fall on a 4 mil pitch. This restricts the width of the l/O buffer macro to approximately 100 urn. With the macro port pitch restricted to 18 urn this leaves only 6 possible ports per l/O macro. (fig. 3)

   To be able to offer our customers the versatility they would like the l/O macro library must include bidirectional macros with functions up to the complexity of a latch. If we have only six ports available we would not be able to meet our versatility goals. For example an or/nor twin ouput input combined with a 2 to 1 mux output would require 4 ports for the input and 3 ports for the output. This would not be possible with the present port configuration.

   The 18 urn port pitch restriction leaves us with available routing channels between port locations. By utilizing those routing channels we...