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5.1.4 Device Changes and Optimizations

Circuit design relies on model values from a mean device with a given low sensitivity towards process variations. Thus, device fabrication and optimization requires to account for statistical decision principles in the optimization process as shown in Fig. 5.4. Mathematically, a desired change to a device is a multivariate problem where only very few of the variables are actually known and can be influenced. To include external variables in a more abstract optimization process, external decision loops are added. The inner loop of the actual change procedure addresses whether the specific device properties are reached. However, a change can be called optimization, if the external requirements are added by additional loops to account for the unknowns in this multivariate problem. The two most important loops are:

Only if the external considerations are fulfilled, a device change can be truly called optimization.

Figure 5.4: Inclusion of external variables into the optimization process.


\includegraphics[width=13 cm]{D:/Userquay/Promotion/HtmlDiss/fig82ca.eps}

Figure 5.5: Sensitivity analysis of a $ S_{21}$ towards $ d_{gc}$ variations as a function of frequency.


\includegraphics[width=10 cm]{D:/Userquay/Promotion/HtmlDiss/fig82d.eps}


next up previous
Next: 5.1.5 Device Simulation and Up: 5.1 Statistical Analysis of Previous: 5.1.3 Factor Interpretation
Quay
2001-12-21