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Automatic Length Compensation for Analog Integrated Circuit Routing. Lars Schreiner (Cadence Design Systems, Inc.). Erich Barke (University of Hannover). Matthew A. Smith (Foley & Lardner LLP). Volker Meyer-zu-Bexten (ATMEL Germany GmbH). Overview. Problems to be Solved. Approach.
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Automatic Length Compensation for Analog Integrated Circuit Routing
Lars Schreiner (Cadence Design Systems, Inc.) Erich Barke (University of Hannover) Matthew A. Smith (Foley & Lardner LLP) Volker Meyer-zu-Bexten (ATMEL Germany GmbH)
Overview • Problems to be Solved • Approach • Results • Summary
Overview • Problems to be Solved • Approach • Results • Summary
PARSY • Analog Router • One goal (of many): balance parasitic loads on interconnects • During routing length differences between bus traces occur LOCAL GLOBAL Terminal: Beginning of a “Net Bundle”
Length Compensation Create a Geometry Equalizes Trace Lengths L=100 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=100 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=100 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=100 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=120 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=120 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=120 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=120 L=110 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=120 L=120 L=120
Length Compensation Create a Geometry Equalizes Trace Lengths L=120 L=120 L=120
A More Difficult Case L=150 L=200 L=100 L=200 L=120
A More Difficult Case Find the longest trace(s) L=150 L=200 L=100 L=200 L=120
A More Difficult Case Make all lengths 200 L=150 L=200 L=100 L=200 L=120
A More Difficult Case L=150 L=200 L=100 L=200 L=120
A More Difficult Case L=150 L=200 L=100 L=200 L=120
A More Difficult Case L=150 L=200 L=100 L=200 L=120
A More Difficult Case L=150 L=200 L=100 L=200 L=120
A More Difficult Case L=200 L=200 L=100 L=200 L=120
A More Difficult Case L=200 L=200 L=100 L=200 L=120
A More Difficult Case L=200 L=200 L=100 L=200 L=120
A More Difficult Case L=200 L=200 L=100 L=200 L=120
A More Difficult Case L=200 L=200 L=100 L=200 L=120
A More Difficult Case L=200 L=200 L=100 L=200 L=200
A More Difficult Case L=200 L=200 L=100 L=200 L=200
A More Difficult Case Middle trace uncompensated L=200 L=200 L=100 L=200 L=200
A More Difficult Case Middle trace uncompensated Needs room for compensation geometry L=200 L=200 L=100 L=200 L=200
A More Difficult Case Middle trace uncompensated Needs room for compensation geometry HOWEVER L=200 L=200 L=100 L=200 L=200
A More Difficult Case Middle trace uncompensated Needs room for compensation geometry HOWEVER To make room, other traces must be moved (lengthened) L=200 L=200 L=100 L=200 L=200
Problem To Be Solved • General Length Compensation Problem for Parallel Traces
Problem To Be Solved • General Length Compensation Problem for Parallel Traces • Arbitrary Number of Traces
Problem To Be Solved • General Length Compensation Problem for Parallel Traces • Arbitrary Number of Traces • Arbitrary Lengths, Widths and Spacings
Characteristics of a Good Solution • Compensates Trace Lengths
Characteristics of a Good Solution • Compensates Trace Lengths • Introduces Minimal Extra Trace Length
Characteristics of a Good Solution • Compensates Trace Lengths • Introduces Minimal Extra Trace Length • Keeps Footprint Small
Characteristics of a Good Solution • Compensates Trace Lengths • Introduces Minimal Extra Trace Length • Keeps Footprint Small • Introduces Few Additional Bends
Characteristics of a Good Solution • Compensates Trace Lengths • Introduces Minimal Extra Trace Length • Keeps Footprint Small • Introduces Few Additional Bends • Flexible and Easy to Implement
Overview • Problems to be Solved • Approach • Results • Summary
Overview • Problems to be Solved • Approach • Results • Summary
Ripple Compensation • Multiple copies of a simple compensation geometry
Ripple Compensation • Multiple copies of a simple compensation geometry RH
Ripple Compensation • Multiple copies of a simple compensation geometry RH • A fixed height RH is chosen for the compensation geometry
Ripple Compensation • Multiple copies of a simple compensation geometry RH • A fixed height RH is chosen for the compensation geometry • Number of ripples determined by dividing length to be added by 2RH