An off-chip current sensor for IDDQ testing of CMOS ICs

This paper presents the design of an off-chip current sensor for IDDQ testing of CMOS ICs. An operational amplifier is used to maintain a virtual ground so that the insertion of the sensor in series with the circuit under test (CUT) does not degrade the operating voltage across the CUT during testing. A voltage controlled switch is used to bypass the transient current peaks. The current (IDDQ) is directly converted to voltage with a conversion factor of 5 mV/μA without any amplification. Computer simulation shows the performance of the sensor to detect different bridging faults in c17 benchmark circuit with a 100 kHz test frequency