文档介绍：Six Sigma Tolerance Design Case Study:
Optimizing an Analog Circuit Using Monte Carlo Analysis
Andy Sleeper
essful Statistics LLC
970-420-0243
andy@
1. Abstract
Tolerance Design is the science of predicting the variation in system
performance caused by variations ponent values or the environment. This
article shows how Monte Carlo simulation can be applied to predict and improve
the quality of a system before even one prototype has been built. Using these
methods allows new products to be developed rapidly and introduced with fewer
unexpected problems. The case study in this article is a simple analog circuit.
The analytical methods and optimization process may be essfully applied to
any engineering problem where a transfer function can be derived.
2. Overview of Tolerance Design
In general, any product or process is a system converting inputs to outputs. This
is shown graphically in Figure 1.
At the center of the system is a System Characteristics
Transfer function, which converts the
Outputs
inputs (X) into outputs (Y). The Y
transfer function is a mathematical
equation, which may be known,
estimated, or unknown.
Transfer function
Y = f(X)
These three types of transfer
functions mon in engineering
problems: X
• White box transfer functions Inputs
are derived analytically, using Part Characteristics
principles of science and Process Characteristics
engineering. Environmental Characteristics
• Gray box transfer functions
are estimated by simulating Figure 1 - Generic System
the behavior of the system,
puter programs like
SPICE. The function itself may be plicated to derive, or it may
have no closed-form solution.
© 2003 essful Statistics LLC 1
• Black box transfer functions are estimated by observing the behavior of a
physical system. This is done by designing an orthogonal experiment,
collecting the data, and estimating the transfer functio