Performance Performance Optimization Global Optimization Global Routing with RLC Routing with RLC Crosstalk Constraints Crosstalk Constraints Ling Zhang, Ling Zhang, Tong Jing, Tong Jing, Xianlong Hong, Jingyu Xu Xianlong Hong, Jingyu Xu Jinjun Xiong, Lei He Jinjun Xiong, Lei He Dept. of CST, Tsinghua Univ Dept. of EE, UC, Los Angeles Dept. of CST, Tsinghua Univ Dept. of EE, UC, Los Angeles
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Performance Optimization Global Routing with RLC Crosstalk Constraints
Performance Optimization Global Routing with RLC Crosstalk Constraints. Ling Zhang, Tong Jing, Xianlong Hong, Jingyu Xu Jinjun Xiong, Lei He Dept. of CST, Tsinghua Univ Dept. of EE, UC, Los Angeles. Outline. Introduction Previous Work - PowerPoint PPT Presentation
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Performance Optimization Performance Optimization Global Routing with RLC Global Routing with RLC
Crosstalk Constraints Crosstalk Constraints
Ling Zhang,Ling Zhang, Tong Jing, Tong Jing, Xianlong Hong, Jingyu Xu Jinjun Xiong, Lei HeXianlong Hong, Jingyu Xu Jinjun Xiong, Lei He
Dept. of CST, Tsinghua Univ Dept. of EE, UC, Los AngelesDept. of CST, Tsinghua Univ Dept. of EE, UC, Los Angeles
Previous Work (1)Previous Work (1)Noise minimizationNoise minimization
Spacing in detailed routingSpacing in detailed routing (K. Chaudhary, A. Onozawa et al, 1993)
Track permutation in detailed routingTrack permutation in detailed routing (T. Gao, C. L. Liu, 1996)
WWire perturbationire perturbation in detailed routing in detailed routing (P. Saxena, C. L. Liu, 1999)
Crosstalk reduction after global routingCrosstalk reduction after global routing (T. X. Xue, E. S. Kuh, D. F. Wang, 1997) (J. J. Xiong, J. Chen, J. Ma, L. He, 2002)
The major contribution of this workThe major contribution of this work We present a performance optimization We present a performance optimization
global routing algorithm, named CEE-Gr, global routing algorithm, named CEE-Gr, with RLC crosstalk constraints.with RLC crosstalk constraints.
To our knowledge, it is the first to study To our knowledge, it is the first to study RLC coupling noise, timing performance, RLC coupling noise, timing performance, and routability simultaneously at global and routability simultaneously at global routing level.routing level.
Gr: Timing and congestion optimization Gr: Timing and congestion optimization CEE: Crosstalk estimation and elimination CEE: Crosstalk estimation and elimination
Gr firstly generates an initial routing solution considering congestion and timing optimization
Then, CEE eliminates the crosstalk from the solution by inserting shields and gets a mid-result
Finally, regard the mid-result as input and send it to Gr for iterations
Congestion and timing optimization Congestion and timing optimization
Based on our previous methodsBased on our previous methods SSTT (search space traversing technology) and RINO SSTT (search space traversing technology) and RINO
(considering independent of net ordering)(considering independent of net ordering) (T. Jing, X. L. Hong, H. Y. Bao, Y. C. Cai, J. Y. Xu, 2001)
Critical-network-based technologyCritical-network-based technology (T. Jing, X. L. Hong, H. Y. Bao, Y. C. Cai, J. Y. Xu et al, 2002)
(2) CEE (1)(2) CEE (1) Eliminate crosstalk in each GRG:Eliminate crosstalk in each GRG:
According to each , this step applies According to each , this step applies simulated annealing method in each region to simulated annealing method in each region to insert shields, so that all region’s crosstalk is insert shields, so that all region’s crosstalk is within bound value. within bound value.
Local Refinement: Local Refinement: Check each net to eliminate possible remnant Check each net to eliminate possible remnant
crosstalk and delete unnecessary shields to crosstalk and delete unnecessary shields to minimize the area. minimize the area.
Consider different congestion situation in Consider different congestion situation in different GRG region in partitioning. Thus, different GRG region in partitioning. Thus, introduce a linear programming problem. introduce a linear programming problem.
The objective is to minimize the number of The objective is to minimize the number of used tracks in most congested GRG region.used tracks in most congested GRG region.
DiscussionsDiscussions CEE-Gr can eliminate all crosstalk by adding shields, CEE-Gr can eliminate all crosstalk by adding shields,
while the initial solution has serious crosstalk.while the initial solution has serious crosstalk. The increase in wire length of CEE-Gr is quite small The increase in wire length of CEE-Gr is quite small
compared to Gr.compared to Gr. The minimum redundancy of delay (The minimum redundancy of delay (requiredDelay-requiredDelay-
currentDelaycurrentDelay) is almost unaffected. ) is almost unaffected. CBUD strategy consumes less shields and small area CBUD strategy consumes less shields and small area
than than CBLP strategy.CBLP strategy. CBLP reduces the maximal used tracks in GRG, which CBLP reduces the maximal used tracks in GRG, which
is helpful for optimization with other constraints and low is helpful for optimization with other constraints and low power design.power design.
Simulated annealing method increases the running Simulated annealing method increases the running time of CEE-Gr.(40 mins for C2)time of CEE-Gr.(40 mins for C2)
Tackle coupling noise, timing performance and routability simultaneously
Take coupling inductance into consideration
Obtain good routing results
Efficiently eliminate crosstalk throughout the global routing phase by inserting shields and has little influence on wire length and timing performance.