| Summary: | 碩士 === 國立交通大學 === 電機工程學系 === 106 === As far as Internet-of-Everything (IoE) devices are concerned, strong hardware security and low electromagnetic interference (EMI) are design requirements for power management to guarantee personal data protection. Conventional linear feedback shift register (LFSR) based loop randomization technique has the ability to avoid the power side channel attacks (PSCA), but the power injection attack (PIA) results in limited random number (RN) due to the predictability and reproducibility of the LFSR, and thus cause the loop randomization cracked and vulnerable to the PSCA. Besides, the PIA not only narrows the LFSR based random switching frequency but also reduces the triangular modulation frequency to around 1/N times of the switching frequency. Consequently, the EMI noise floor fails to meet the specification of EN 55032 Class B. Other techniques offer counter-measures to improve resistance against malicious attacks but result in either greatly increased power consumption or large hardware overhead.
In this thesis, the true random number (TRN) based pseudo hysteresis controller (PHC) and the enhanced security randomizer (ESR) are proposed to avoid both PSCA and PIA simultaneously and reduce EMI without degrading performance. The ESR is capable of generating input-supply-independent RN correctly under PSCA and PIA. The TRN based PHC converts the RN to the hysteresis window that constitutes a true random modulated switching frequency, thereby ensuring suitable spread spectrum and low EMI. Besides, fast transient response is maintained due to inherent hysteresis control. Experimental results show peak EMI noise is reduced from 89.72dBμV to 54.32dBμV and meets the specification of EN 55032 Class B even under the PIA interference up to 1V. Furthermore, transient performance achieves 7.3μs recovery time and 53mV drop of output voltage in case of 0.2A-to-0.8A load step at the switching frequency around 1MHz and peak efficiency is 92.4%.
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