A Multiple-objective ILP based Global Routing Approach for VLSI ASIC Design

A VLSI chip can today contain hundreds of millions transistors and is expected to contain more than 1 billion transistors in the next decade. In order to handle this rapid growth in integration technology, the design procedure is therefore divided into a sequence of design steps. Circuit layout is the design step in which a physical realization of a circuit is obtained from its functional description. Global routing is one of the key subproblems of the circuit layout which involves finding an approximate path for the wires connecting the elements of the circuit without violating resource constraints. The global routing problem is NP-hard, therefore, heuristics capable of producing high quality routes with little computational effort are required as we move into the Deep Sub-Micron (DSM) regime. In this thesis, different approaches for global routing problem are first reviewed. The advantages and disadvantages of these approaches are also summarized. According to this literature review, several mathematical programming based global routing models are fully investigated. Quality of solution obtained by these models are then compared with traditional Maze routing technique. The experimental results show that the proposed model can optimize several global routing objectives simultaneously and effectively. Also, it is easy to incorporate new objectives into the proposed global routing model. To speedup the computation time of the proposed ILP based global router, several hierarchical methods are combined with the flat ILP based global routing approach. The experimental results indicate that the bottom-up global routing method can reduce the computation time effectively with a slight increase of maximum routing density. In addition to wire area, routability, and vias, performance and low power are also important goals in global routing, especially in deep submicron designs. Previous efforts that focused on power optimization for global routing are hindered by excessively long run times or the routing of a subset of the nets. Accordingly, a power efficient multi-pin global routing technique (PIRT) is proposed in this thesis. This integer linear programming based techniques strives to find a power efficient global routing solution. The results indicate that an average power savings as high as 32\% for the 130-nm technology can be achieved with no impact on the maximum chip frequency

Simultaneous buffer and wire sizing for performance and power optimization

In this paper, we study the simultaneous buffer and wire sizing (SBWS) problem for delay and power dissipation minimization. We prove the BS/WS relation for optimal SBWS solutions. This relation leads to a polynomial time algorithm for computing the lower and upper bounds of the optimal SBWS solutions, which enables an efficient optimal algorithm for computing optimal SBWS solutions. We have applied the SBWS algorithms to the clock nets in a spread spectrum IF transceiver chip andHSPICE simulations show that our algorithms canreduceskew and power by a factor of 3:5X and 1:6X , respectively, when compared to the manual layout of the clock nets in the original chip. 1 Introduction As the VLSI fabrication technology advances to submicron device dimension and gigahertz clock frequency, it is important to consider and optimize both device (i.e. transistor/cell) design and interconnect design simultaneously in order to achievethe objective of delay andpower minimization. The objective of t..

Simultaneous Buffer and Wire Sizing for Performance and Power Optimization

In this paper, we study the simultaneous buffer and wire sizing (SBWS) problem for delay and power dissipation minimization. We prove the BS/WS relation for optimal SBWS solutions. This relation leads to a polynomial time algorithm for computing the lower and upper bounds of the optimal SBWS solutions, which enables an efficient optimal algorithm for computing optimal SBWS solutions. We have applied the SBWS algorithms to the clock nets in a spread spectrum IF transceiver chip andHSPICE simulations show that our algorithms canreduceskew and power by a factor of 3 5X and 1 6X , respectively, when compared to the manual layout of the clock nets in the original chip