Quiescent leakage current (IDDQ) test has proven very effective for detecting defects that escape other test methods, such as small delay faults or reliability hazards. However, leakage currents in microprocessors, digital signal processors, and graphics processors have risen to the point that these products no longer use IDDQ test. Quality must be achieved through other test methods, often at higher development and application cost. We propose to bring IDDQ test back to high performance chips by using a practical built-in current sensor (BICS). 180 nm test chip results show that a small sensor can achieve a resolution of 54 ?A, which is adequate to detect most small delay defects and reliability hazards.