ABSTRACT
There are many sources of physical faults: improper interconnections between parts, improper assembly, missing parts, and erroneous parts may occur while the circuit is being manufactured. After manufacturing, the circuit may fail due to excessive heat dissipation or for mechanical reasons associated with corrosions and, in general, bad maintenance. Short-circuit faults are those due to connections of signal lines that must be disconnected. In addition, disconnecting lines that must be connected may cause open-circuit faults.1,3
Failures in the operation of digital circuits are addressed in the testing process, which is abstracted in Fig. 14.1. Typically, the testing process determines the presence of faults. The circuit being tested is often called the circuit under test (CUT). Errors are detected by applying test patterns on the inputs of the CUT and analyzing the responses on its outputs. A test pattern is typically a vector of 0 and 1, and every bit corresponds to an input of the CUT. A test pattern is generated by a test pattern generator (TPG) tool. The responses are analyzed using an output response verification (ORV) tool. The ORV tool is a comparator circuit.
