Placement and beyond in honor of Ernest S. Kuh

  • Authors:
  • Chung-Kuan Cheng

  • Affiliations:
  • University of California, San Diego, La Jolla, CA, USA

  • Venue:
  • Proceedings of the 2011 international symposium on Physical design
  • Year:
  • 2011

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Abstract

Professor Kuh is a pioneer and giant in physical layout. In this talk, we will describe his influence in placement. His pioneering work from interval graph for one dimensional gate assignment, BBL (Building-Block Layout System for Custom Chip IC Design) [2, 3, 6, 8], BEAR [7] layout system, BAGEL (Gate Array Layout) [17], RAMP (Resistive Analog Module Placement) [5], PROUD (Sea of Gates Placement) [28] to congestion, timing, and low power driven placement, Prof. Kuh always starts with innovative theoretical construction, software system building, and applications with impact on productivity. Physical layout is an indispensable software system for VLSI Design with millions of modules. Placement is the key component of about 500 million dollars market for physical synthesis. In the layout design flow, the placement is the core of the system integrating with other synthesis and analysis tools. For building block layout, Kuh's group tackled the nonslicing architecture. They devised the tile plane to represent the topology of the floorplan and the bottleneck of the routing. A routing order is derived to guarantee 100 percent routing completion [12]. The methodology and algorithms of building block placement [2] were adopted by companies such as Digital Equipment Corporation and ECAD, which was later renamed as Cadence. For standard cell placement, RAMP placement is devised using the analogy of a resistive network [12]. The minimization of the circuit power corresponds to the quadratic wire length reduction. The approach provides a convergent solution in the era of interconnect dominance. As the technology scales, interconnect becomes dominating the system performance in terms on delay and power consumption. Performance driven logic synthesis, signal interconnect with repeater insertion, power ground and clock distribution strongly rely on the physical layout information. On the other hand the placement requires the synthesis result to perform the task. This mutual dependence has caused serious design convergence issues in the 1990s.