I_(DDQ) Test Using Built-In Current Sensing of Supply Line Voltage Drop

摘要

A practical built-in current sensor (BICS) is described that senses the voltage drop on supply lines caused by quiescent current leakage. This non-invasive procedure avoids any performance degradation. The sensor performs analog-to-digital conversion of the input signal using a stochastic process, with scan chain readout. Self-calibration and digital chopping are used to minimize offset and low frequency noise and drift. The measurement results of a 350 nm test chip are described. The sensor achieves a resolution of 182 (mu)A, with the promise of much higher resolution.