An Explicit Model of Delay and Slew Metric for On-Chip VLSI RC Interconnects for Ramp Inputs using Gamma Distribution Function
نویسندگان
چکیده
Moments of the impulse response are widely used for interconnect delay analysis, from the explicit Elmore delay (the first moment of the impulse response) expression, to moment matching methods which creates reduced order trans-impedance and transfer function approximations. However, the Elmore delay is fast becoming ineffective for deep submicron technologies, and reduced order transfer function delays are impractical for the use as early-phase design metrics or as design optimization cost functions. This paper describes an approach for fitting moments of the impulse response to probability density functions so that delay and slew can be estimated accurately at an early physical design stage. For RC trees it is demonstrated that the incomplete gamma function provides a provably stable approximation. We used the PERI (Probability distribution function Extension for Ramp Inputs) technique that extends delay and slew metrics for step inputs to the more general and realistic non-step (i.e. ramp) inputs. The accuracy of our model is justified with the results compared with that of SPICE simulations.
منابع مشابه
An Accurate Modeling of Delay and Slew Metrics for On-chip Vlsi Rc Interconnects for Ramp Inputs Using Burr’s Distribution Function
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