Content deleted Content added
Line 10:
== Fault models ==
{{main|Fault model}}
* single fault assumption: only one fault occur in a circuit. if we define ''k'' possible fault types in our fault model the circuit has ''n'' signal lines, by single fault assumption, the total number of single faults is ''k×n''.
* multiple fault assumption: multiple faults may occur in a circuit.
=== Fault collapsing ===
Line 22:
A pattern set with 100% stuck-at fault coverage consists of tests to detect every possible stuck-at fault in a circuit. 100% stuck-at fault coverage does not necessarily guarantee high quality, since faults of many other kinds—such as bridging faults, opens faults, and transition (aka delay) faults—often occur.
====
This model is used to describe faults for CMOS logic gates. At transistor level, a transistor maybe stuck-short or stuck-open. In stuck-short, a transistor behaves as it is always conducts (or stuck-on), and stuck-open is when a transistor never conducts current (or stuck-off). Stuck-short will produce a short between VDD and VSS.
| |||