SIGNATURE ANALYSIS FOR FAULT-DETECTION OF MIXED-SIGNAL ICS BASED ON DYNAMIC POWER-SUPPLY CURRENT

In this paper we have investigated a unified and simultaneous fault de tection method for mixed-signal integrated circuits. The method is bas ed on the analysis of the power-supply current through the circuit und er test. The analysis has been done paying attention to the dynamic be haviour of the power-supply current, in order to avoid measurement pro blems related to the large amount of quiescent current drop across man y analog blocks. The analysis of the dynamic power-supply current enta ils certain problems related to the complexity of the measurement proc ess, especially those due to the high speed of the current transients. These problems have been addressed by considering a design for test p rocedure based on the use of built-in dynamic current sensors. The goa l of the design for test methodology proposed is to represent the Iddt through the mixed-signal IC under test by a digital signature. The pa per presents some advantages of this approach such as a good tolerance to crosstalk noise and the need for only a conventional digital teste r on the complete mixed-signal IC for fault detection. The analysis is illustrated with some test results.