Layout Tips for 12-Bit A/D Converter Application:This Application Note originally started as a “cook
book” for a true 12-bit layout. The assumption of this
type of approach is that a reference design could be
provided, which easily could be used for every layout
implementation. But, the notion of this approach is fairly
unrealistic. There are a multitude of successful ways to
layout out systems with 12-bit Analog-to-Digital (A/D)
Converters and each layout is highly dependent on the
number of devices in the circuit, the types of the
devices (digital or analog) and the environment that the
final product will reside in. Given all of these variables,
it could easily be demonstrated that one successful layout
that provides twelve noise free bits from an analog
signal may easily fail in another setting.
Because of the complexity of this problem, this Application
Note will provide basic guidelines, ending with a
review of issues to be aware of. Throughout the application
note, examples of good layout and bad layout
implementations will be presented. This will be done in
the spirit of discussing concepts and not with the intent
of recommending one layout as the only one to use.