A comparator-based IDDQ testing of CMOS analog and mixed-signal integrated circuits

A new built-in current sensor (BICS) has been proposed in this paper for the detection of open and short faults. The BICS compares the quiescent current from the circuit under test (CUT) with the reference current. If a fault is detected it gives ±2.5 V at the output depending on the nature of defect. A two stage CMOS op-amp, 3 bit flash architecture based ADC, 3 bit charge scaling architecture based DAC have been used as the CUT. The faults in the circuits have been introduced using fault injection transistors (FITs). A combination of nine open and short faults has been randomly embedded in the op-amp. Twenty three faults were embedded in 3 bit ADC and ten faults were embedded in 3 bit DAC.