Leakage Monitoring Technique in Near-Threshold Systems with a Time-Based Bootstrapped Ring Oscillator

The paper presents a built-in self-testing (BIST) technique for leakage monitoring using a time-based bootstrapped sensor at near-threshold supply. In order to observe critical leakage behavior in near-threshold systems, the BIST circuit duplicates the leakage current and a leakage quantizer converts the sensed current into digital outputs. Moreover, a bootstrapped ring oscillator (BTRO) serves as an ultra low-voltage sensor to operate even in deep sub-threshold region. It suppresses most of the leakage current and has high energy efficiency to convert sensed leakage current to oscillation frequency. As a result, it monitors leakage current from the circuit under test (CUT) and quantizes the leakage to high resolution digital outputs. In addition, our design also can be used to monitor the process variation in the ultra low-voltage application. The design and test technique is simulated in 90 nm 1P9M SPRVT CMOS process. As compared to state-of-art works, the proposed sensor can operate even at 0.2 to 0.4V VDD in different corners. Besides, it achieves 11-bit resolution under 10us testing time.