Routing of Analog Busses with Parasitic Symmetry Lars Schreiner, Markus Olbrich, Erich Barke, Volker Meyer zu Bexten

Lars Schreiner: ISPD Contents Motivation Net Bundle Routing Trapezoid Methodology Results Conclusions/Future Work

Lars Schreiner: ISPD Contents Motivation Net Bundle Routing Trapezoid Methodology Results Conclusions/Future Work

Lars Schreiner: ISPD Motivation Groups of wires (net bundles) have to be routed symmetrically -Symmetry = equal capacitive coupling and resistance for each wire Automatic balancing of wire length Automatic generation of shielding patterns Automatic generation of slotted/split wires

Lars Schreiner: ISPD Example of a Net Bundle with Parasitic Symmetry

Lars Schreiner: ISPD Contents Motivation Net Bundle Routing Trapezoid Methodology Results Conclusions/Future Work

Lars Schreiner: ISPD Steps of Net Bundle Routing Calculation of virtual terminals and net order Path search for net bundle Routing of the net bundle to the terminals Calculation of wire length differences and adjustment area search Use of Module generator for wire implementation

Lars Schreiner: ISPD Basic Procedure T2a T2b T1a T1b = Virtual Terminal = Terminal 1234

Lars Schreiner: ISPD Separation of Terminal/Net Bundle Routing Nets are treated and routed together as bundles. Technology independent module generators can be used. Problem complexity is reduced. Keeping symmetry is easier.

Lars Schreiner: ISPD Net Ordering During Path Search (1) „False“ net order of the right terminal bundle Consideration during path search necessary terminal bundle virtual terminal BUS-module from Module generator

Lars Schreiner: ISPD Net Ordering During Path Search (2) Possible solution of example

Lars Schreiner: ISPD Contents Motivation Net Bundle Routing Trapezoid Methodology Results Conclusions/Future Work

Lars Schreiner: ISPD T- and L-Structures of Trapezoid Methodology = = Generator call: BUS N=3 LENGTH=4e-5 WIDTH=5e-6 LAYER=2 BEVELSTART=45 BEVELEND=0 -45° 0°

Lars Schreiner: ISPD Benefits of Trapezoid Methodology Universal use for many geometries -Lines, T- and L-structures are implemented by the same module generator Technology information hidden in module generator -Router gets only necessary technology information -Shielding and Slotting are hidden in the generator Easy maintainability and adaptation to new technologies

Lars Schreiner: ISPD Adjustment Modules Shorter wires have to be stretched Two cases: -Adjustment to the favorable site -Adjustment to the unfavorable site Problem: Bent or terminal connection Solution: Adjustment modules

Lars Schreiner: ISPD Examples of Adjustment Modules

Lars Schreiner: ISPD Benefits of Adjustment Modules Wire length balancing is done by module generator. Different net bundle modules are generated for balancing bents, asymmetries, etc. Resistive differences are adjusted. Capacitive balancing is possible.

Lars Schreiner: ISPD Contents Motivation Net Bundle Routing Trapezoid Methodology Results Conclusions/Future Work

Lars Schreiner: ISPD Hand Made vs. Router

Lars Schreiner: ISPD Symmetric Coupling Consideration During Path Search

Lars Schreiner: ISPD Contents Motivation Net Bundle Routing Trapezoid Methodology Results Conclusions/Future Work

Lars Schreiner: ISPD Conclusion Routing of net bundles Consideration of routing constraints -Parallel wires -Symmetric capacitive coupling -Wire length difference calculation -Symmetric terminal connection Module generators -Trapezoid methodology -Adjustment modules

Lars Schreiner: ISPD Future Work 45° Routing Twisted wires Inductances