Delay evaluation is always a crucial concern in the VLSI design and it becomes increasingly more critical in the nowadays deep-submicron technology. To obtain an accurate delay value, the gate modeling is a key issue. As the VLSI feature size scaling down and meanwhile operating frequency increasing, the modeling work becomes more difficult than ever for high-performance digital ICs. Nevertheless, most conventional techniques of gate modeling are based on the switch-resistor model (i.e., a voltage source concatenating a driving resistance), which can only capture the gate characteristic in its switching region. Hence, these modeling techniques have to decouple the gate with its interconnects and compute a piecewise linear function for the driving source in the iterative computation of effective capacitance [1, 3, 4]. Since the driving source of the model is dependent on gate load, when the design modification affects the load, the gate has to be modeled again almost from the beginn...
Muzhou Shao, Martin D. F. Wong, Huijing Cao, Youxi