RSPICE: A Fast and Robust Timing Simulator for Digital MOS VLSI

Xia CAI  Huazhong YANG  Yaowei JIA  Hui WANG  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.11   pp.2492-2498
Publication Date: 1999/11/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on VLSI Design and CAD Algorithms)
fast timing simulation,  analytical solution,  table-based MOS model,  waveform relaxation,  

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RSPICE, a fast timing simulator for large digital MOS circuits, is presented in this paper. A new table-based region-wise linear MOS transistor model and the analytical solution of the generic sub-circuit primitive are applied to calculate the transient response of digital MOS circuits. The body effect of pass transistors is included in the MOS model and the floating capacitor network can be handled by this sub-circuit primitive as well. In RSPICE, MOS transistors with a DC path are grouped into a DC-connected block (DCCB), and DCCBs with a feedback path are combined as a strongly connected component (SCC). RSPICE orders SCCs by Tarjan's algorithm and simulates ordered SCCs one by one. DCCBs are basic cells in RSPICE and any DCCB can be mapped into one or more sub-circuit primitives. In order to calculate the transient response of these primitives analytically, RSPICE approximates the input signals of the primitive by piecewise linear functions. To compromise the simulation accuracy and run time, partial waveform and partial time convergent (PWPTC) combined with dynamic windowing technique is applied to simulate SCCs. Other key issues of RSPICE, such as circuit partition, pass-transistor and floating-capacitor processing, simulation-flow control and waveform modification are also discussed in detail. Compared with HSPICE , the simulation result of RSPICE is very accurate with an error less than 3%, but the speed is 1-2 orders over HSPICE.