A DIFFERENTIAL BUILT-IN CURRENT SENSOR DESIGN FOR HIGH-SPEED IDDQ TESTING

A new built-in current sensor design for IDDQ testing is presented in this paper, Our design overcomes performance limitations encountered b y previous sensors by using a novel differential architecture which al lows early and accurate detection of abnormal quiescent current follow ing the switching transient, This differential design also naturally c ompensates for inaccuracies due to any build up of leakage currents an d subthreshold conduction effects when relatively large circuit partit ions are tested, A test circuit utilizing the sensor in a built-in sel f-test environment has been fabricated, At clack speeds of up to 31.25 MHz the sensor accurately detects all six of the defects that were im planted in the test chip, SPICE3 simulations of the circuit indicate t hat with careful design, this sensor can accurately detect faults at o perational speeds in a variety of situations.