Current Information In The Ic Fault Diagnosis Applied Research

Faults diagnosis is an important part of the integrate circuit (IC) design and production. Diagnosis is composed of faults detection and location. The traditional function testing methods based on voltage have been mature in basic researches. And it has been widely used in practice. But this method can't detect some kinds of faults under some high performance ICs. Recently, a novel fault diagnosis technology including IDDQ and IDDT has developed rapidly. These new methods adopt the circuit information contained in the power supply line current to realize the fault diagnosis. It can increase the fault coverage, reduce testing cost and improve the quality and reliability of ICs. It has been an important supplement to the diagnosis method based on voltage detection. Though there is a great future for current testing method, it still needs a lot of researches to solve problems.This paper is mainly about some researches in three areas: IDDQ detecting method, IDDT detecting method and fault location algorithm. In IDDQ detecting area, the basic principle and strongpoint of IDDQ testing are introduced. Then, the influence of deep-submicron technology on IDDQ testing is explained. And the improved IDDQ testing methods are also given. Through the simulative experiments about IDDQ detecting bridge faults in CMOS and BiCMOS circuits, the fault coverage of IDDQ can be estimated. In IDDT detecting area, firstly analyzed the feasibility of IDDT testing. Then, the basic principle and current process methods of IDDT are described. And through simulative experiments by PSPICE, the analysis of the test results for short faults, open faults and transistor parameter errors in CMOS and BiCMOS circuits are given. In addition, appropriate current testing methods for delay fault which is hard to detect are also discussed. In fault location area, a novel algorithm for fault location using IDDQ and IDDT is designed in this paper. This algorithm is realized by combination of IDDQ and IDDT based on Wavelet transform. After classification of the potential faults by pattern recognition, the actual faults can be accurately located effectively. Experiments have proved that the algorithm was realizable and effective.