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16th Conference on Advanced Research in VLSI (ARVLSI'95)
HAL: heuristic algorithms for layout synthesis
Chapel Hill, North Carolina
March 27-March 29
ISBN: 0-8186-7047-9
S. Rekhi, Mississippi State Univ., MS, USA
J.D. Trotter, Mississippi State Univ., MS, USA
This paper describes graph theory based algorithms for layout synthesis of leaf cells. A new layout style termed 1-1/2-d layout style is used for the layouts. The transistors are aligned based on common poly gates or common circuit nodes between two sets of transistors. The two sets of transistors can be a set of PMOS transistors and a set of NMOS transistors, or both the sets can be formed by similar types of transistors. This layout style and the choice of transistor sets provide a unique capability of making efficient use of the layout area for circuits with a large difference in the number of PMOS and NMOS transistors. The algorithms can thus be used to form symbolic layouts for a general class of CMOS circuits, e.g., static dual type of circuitry or static CMOS circuitry with non-dual pullup and pulldown networks and dynamic logic styles (e.g., CPL, Domino, etc.). The algorithms have been implemented in GENIE (Mentor Graphics). In spite of possessing the extra features not usually found in the other algorithms in the literature, these algorithms provide extremely competitive results when compared to the handcrafted layouts and other algorithms in the literature. These algorithms are not only quite flexible in supporting various circuit styles, but are also run time efficient.
Index Terms:
circuit layout CAD; logic CAD; graph theory; CMOS logic circuits; network topology; heuristic algorithms; layout synthesis; graph theory based algorithms; leaf cells; common poly gates; 1-1/2-d layout style; common circuit nodes; transistor sets; layout area; symbolic layouts; CMOS circuits; static dual type; static CMOS circuitry; pullup network; pulldown network; dynamic logic styles; GENIE; run time efficient
Citation:
S. Rekhi, J.D. Trotter, "HAL: heuristic algorithms for layout synthesis," arvlsi, pp.185, 16th Conference on Advanced Research in VLSI (ARVLSI'95), 1995
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