Current Testing of CMOS Combinational Circuits with Single Floating Gate Defects

Abstract

The behavior of basic CMOS combinational gates in the presence of a floating gate defect is characterized in order to investigate its detectability by IDDQ . The defect is modeled at the circuit level by the poly-bulk and metal-poly capacitances, which determine the quiescent power supply current consumption (IDDQ ) of the defective circuit. The testing implications on the type of defective gate are studied. Experimental measures have been made on basic CMOS combinational modules designed with intentional floating gate defects. A good agreement is observed between the simulation results and the experimental data. A conventional ATPG for stuck-at faults is used to obtain the required exciting vector to test the floating gate defects by IDDQ Testing.