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Modeling Process Variability in Scaled MOSFETs
8.5 Statistical Compact Modeling
In the conventional variability modeling approaches, a standard set of model
parameters are used for fixed corner modeling or a large number of model
files are generated from ET data. The fixed corner models are inadequate,
whereas, ET data–based modeling is resource-intensive. Therefore, an analytical technique to obtain the process-sensitive compact model parameters
of any industry standard compact model to generate compact variability model library for circuit analysis is crucial for variability-aware circuit
design as described in the following section.
A generalized approach for process variability modeling is shown in
Figure 8.7. The method includes selection of target compact model, consideration of basic I ds expression, derivation of a generalized expression of I ds variance, selection of device parameters causing process-induced I ds variation,
Select target compact model
(e.g., BSIMx, PSP, HiSIM)
Consider simplified (I−V) model
Derive current variance equation
Identify (I−V )/(C−V ) variability-sensitive
major device parameters
Map each variability-sensitive device parameter
to
corresponding compact model parameter
Compute variance for
each variation-sensitive compact model parameters
Build statistical model library for
variability-aware VLSI circuit design
FIGURE 8.7
Generalized modeling approach for process variability-aware VLSI circuit design; here, BSIMx,
PSP, and HiSIM represent industry standard MOSFET compact models; where x = 3, 4, and 6.
(Data from S.K. Saha, IEEE Access, 2, 104–115, 2014.)
Modeling Process Variability in Scaled MOSFETs
8.5 Statistical Compact Modeling
In the conventional variability modeling approaches, a standard set of model
parameters are used for fixed corner modeling or a large number of model
files are generated from ET data. The fixed corner models are inadequate,
whereas, ET data–based modeling is resource-intensive. Therefore, an analytical technique to obtain the process-sensitive compact model parameters
of any industry standard compact model to generate compact variability model library for circuit analysis is crucial for variability-aware circuit
design as described in the following section.
A generalized approach for process variability modeling is shown in
Figure 8.7. The method includes selection of target compact model, consideration of basic I ds expression, derivation of a generalized expression of I ds variance, selection of device parameters causing process-induced I ds variation,
Select target compact model
(e.g., BSIMx, PSP, HiSIM)
Consider simplified (I−V) model
Derive current variance equation
Identify (I−V )/(C−V ) variability-sensitive
major device parameters
Map each variability-sensitive device parameter
to
corresponding compact model parameter
Compute variance for
each variation-sensitive compact model parameters
Build statistical model library for
variability-aware VLSI circuit design
FIGURE 8.7
Generalized modeling approach for process variability-aware VLSI circuit design; here, BSIMx,
PSP, and HiSIM represent industry standard MOSFET compact models; where x = 3, 4, and 6.
(Data from S.K. Saha, IEEE Access, 2, 104–115, 2014.)