Cadence Mixed-Signal Circuit Design Environment User Guide
The Mixed-Signal Interface
Product Version 5.0
Nondetailed IE Generation
In nondetailed IE generation mode, all digital pins connected to an interface net are
represented by one interface element. There can be only one IE at an interface net. For
information on the FNL nondetailed IE generation mode, see "Flat Netlisting" on page 132.
For information on the HNL nondetailed IE generation mode, see "Hierarchical Netlisting" on
The IE generator selects the interface element at a net having multiple digital instance
terminals using the following rules:
If there is one digital output driver on the interface net, the IE generator inserts a D2A
macro model corresponding to that driver.
If there are multiple digital output drivers on an interface net, the IE generator uses the
first one it encounters and inserts a D2A model corresponding to that driver.
If there are multiple digital inputs on an interface net, the IE generator uses the first one
it encounters and inserts an A2D model corresponding to that input.
When there is more than one digital pin at an interface net, the IE generator displays warnings
about the possibility of multiple fan in and fan out problems. Review these situations
In both flat netlisting (FNL) mode and hierarchical netlisting (HNL) mode used on CDBA, the
IE generator will generate a bidirectional interface element when it encounters a bidirectional
digital terminal connected to an interface net. Because the mixed-signal simulator cannot
simulate bidirectional interface elements, the IE generator reports bidirectional IEs as errors.
In FNL, the selected IE generation mode (detailed or nondetailed) can determine whether
bidirectional IEs are detected and flagged as errors. Bidirectional digital instance terminals
could be detected in one mode but not in the other.
For example, in FNL, when a digital counter is implemented with internal bidirectional
switches and is connected to interface nets, detailed mode could encounter a bidirectional
IE error because the IE generator expands the counter when generating IEs.
As another FNL example, when a CPU with bidirectional data terminals is implemented with
uni-directional logic gates internally driving and sensing the data terminal, nondetailed
mode could encounter a bidirectional IE error because the IE generator does not expand the
CPU when generating IEs.