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A Method for Mitigation of Droop Timing Errors Including a 500 MHz Droop Detector and Dual Mode Logic

Abstract:

A technique to mitigate timing errors induced by power supply droops is featured. We propose an inverter-based droop detector as well as dual mode logic (DML) to achieve a droop-resistant timing response. The droop detector is based on capacitor ratios and is thus less sensitive to process/voltage/temperature (PVT) and to random offset than the prior art. The DML can alter its power/performance ratio based on the droop level input it receives from the detector, such that the critical timings are preserved. A prototype instantiating a demo of the scheme was fabricated in a TSMC 65 nm process, incorporating a simultaneous three-level detector and a DML-based ripple carry adder (RCA). The droop detector consumes 62 μW, has a response time of 2 ns, and an accuracy of 0.9% of Vdd, making it one of the fastest, most accurate, and lowest power droop detectors in its class. The RCA can maintain timing for voltage droops up to 400 mV. A potential supply level reduction of up to 12% was demonstrated for the RCA, and a similar reduction could be achieved with larger-scale DML digital circuits as well.