Testing techniques for VLSI circuits are undergoing many exciting
changes. The predominant method for testing digital circuits consists of
applying a set of input stimuli to the IC and monitoring the logic
levels at primary outputs. If, for one or more inputs, there is a
discrepancy between the observed output and the expected output then the
IC is declared to be defective.
A new approach to testing digital circuits, which has come to be known
as IDDQ testing, has been actively researched for the last
fifteen years. In IDDQ testing, the steady state supply
current, rather than the logic levels at the primary outputs, is
monitored. Years of research suggests that IDDQ testing can
significantly improve the quality and reliability of fabricated
circuits. This has prompted many semiconductor manufacturers to adopt
this testing technique, among them Philips Semiconductors, Ford
Microelectronics, Intel, Texas Instruments, LSI Logic, Hewlett-Packard,
SUN microsystems, Alcatel, and SGS Thomson.
This increase in the use of IDDQ testing should be of
interest to three groups of individuals associated with the IC business:
Product Managers and Test Engineers, CAD Tool Vendors and Circuit
Designers.
Introduction to IDDQ Testing is designed to educate this
community. The authors have summarized in one volume the main findings
of more than fifteen years of research in this area.