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C2 Part 4: VLSI CAD Tools Problems and Algorithms

C2 Part 4: VLSI CAD Tools Problems and Algorithms. Marcelo Johann. EAMTA 2006. Outline. THIRD PART Layout Compaction Logic Synthesis, BDDs Technology Mapping Simmulation vs Formal Verification Voltage Drop by Random Walks FOURTH PART High-Level Synthesis

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C2 Part 4: VLSI CAD Tools Problems and Algorithms

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  1. C2 Part 4: VLSI CAD Tools Problems and Algorithms Marcelo Johann EAMTA 2006

  2. Outline THIRD PART • Layout Compaction • Logic Synthesis, BDDs • Technology Mapping • Simmulation vs Formal Verification • Voltage Drop by Random Walks FOURTH PART • High-Level Synthesis • CDFG, Allocation, Scheduling, Generation

  3. Function representations Truth Tables Lists the output for every input combination • For n variables, 2n lines Formulas F=x1.x2.~x5 + ~x3(x2.x4.x5 + ~x2) + x2.x3 • Not Canonical in general, canonical is large BDDs A graph that packs a truth table • Average sized, powerful representation

  4. BDDs Source: Wikipedia

  5. BDD - good ordering BDD graph for the Boolean formula x1 * x2 + x3 * x4 + x5 * x6 + x7 * x8 using a good variable ordering

  6. BDD - bad ordering BDD graph for the Boolean formula x1 * x2 + x3 * x4 + x5 * x6 + x7 * x8 using a bad variable ordering

  7. Random Walks

  8. Random Walks

  9. IR Drop

  10. Random Walk

  11. The Algorithm Initialize • Compute conductance, px,i , mx For each node in the circuit Loop n times according to accuracy Loop until reaching Supply • Add this node’s cost • Random select the next move Make this node a new supply Print the result

  12. Accuracy 15876 VDD nodes 15625 GND nodes 1.2V Linux 2.8GHz CPU Delta controls error such that 99% of the nodes have less then Error Margin

  13. Jump to… VLSI System DesignPart V : High-Level Synthesis Lecturer : Tsuyoshi Isshiki VLSI Design and Education Center, The University of Tokyo Dept. Communication and Integrated Systems, Tokyo Institute of Technology isshiki@vlsi.ss.titech.ac.jp http://www.vlsi.ss.titech.ac.jp/~isshiki/VLSISystemDesign/top.html

  14. Marcelo Johann johann@inf.ufrgs.br www.inf.ufrgs.br/~johann C2: VLSI CAD Tools Problems and Algorithms Thank you! EAMTA 2006

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