Browse Prior Art Database

A Net Routing Predictor

IP.com Disclosure Number: IPCOM000102821D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 46K

Publishing Venue

IBM

Related People

Rutter, RS: AUTHOR

Abstract

Disclosed is a method to provide a predicted net routing with little computation time, given coordinates of the logic service terminals to be connected by the net.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 79% of the total text.

A Net Routing Predictor

      Disclosed is a method to provide a predicted net routing with
little computation time, given coordinates of the logic service
terminals to be connected by the net.

      The method applies particularly to nets connecting circuits on
a chip that are to be routed using a global wiring program followed
by a bay packer.  The value of the predicted routing is that during
physical design accurate resistance and capacitance estimates can be
made and used for timing and design decisions without wiring.

      The routing created is an estimated Steiner tree connecting the
logic service terminals.  The coordinates are linearly mapped such
that horizontal and vertical segments of equal length in global
wiring cells are of equal mapped length.  The Steiner tree connecting
the mapped points closely approximates the routing by the global
wiring program.  A percentage length growth is then applied to each
segment to account for elongation caused by actual routing
constraints.  Finally, a segment between the Steiner tree and each
logic service terminal is added.  This accounts for wire used to
actually access the terminal.  The elongation and access values are
determined from experience with the actual programs.

      The method is then:
1.  Map the net coordinates into the global wiring cell weighted
space.
2.  Calculate a minimal rectilinear Steiner tree connecting the
points.
3.  Map the resulting segments from the weighted spac...