User`s guide

2 Mixed Analo

/Di

ital Simulation

netlist. The netlist presents a flat view of the circuit (no

hierarchy). Furthermore, PSpice A/D extracts the definitions for

all parts modeled as subcircuits, thus viewing parts as a

collection of primitive devices and node connections.

The digital primitives comprising a given digital part determine

the manner in which PSpice A/D processes an analog/digital

interface to that part. Specifically, the I/O model for each digital

primitive connected at the interface provides PSpice A/D with

the necessary information.

PSpice A/D recognizes three types of nodes: analog nodes,

digital nodes, and interface nodes. The node type is determined

by the types of devices connected to it. If all of the devices

connected to a node are analog, then it is an analog node. If all

of the devices are digital, then it is a digital node. If there is a

combination of analog and digital devices, then it is an interface

node.

PSpice A/D automatically breaks interface nodes into one

purely analog and one or more digital nodes by inserting one or

more analog/digital interface subcircuits.

PSpice A/D also automatically connects a power supply to the

interface subcircuit to complete the generation of the interface.

To view simulation results in Probe at an analog/digital

interface in your schematic:

• Place a marker on the appropriate interface net. The

additional nodes created by PSpice A/D remain transparent.

• View results by selecting traces from Probe’s output

variable list (select Trace from the Add menu). If you use

this approach, you must be aware of the names PSpice A/D

generates for the new nodes.

To find out more, see Interface

Generation and Node Names on

page 15-12.