EQZ-LDO: A Secure Digital Low Dropout Regulator Armed With Detection-Driven Protection Against Correlation Power Analysis

This article presents equalizer (EQZ)-low dropout regulator (LDO), an innovative, secure digital low dropout regulator (DLDO) that integrates an attack detector and a detection-driven protection scheme to mitigate correlation power analysis (CPA). EQZ-LDO incurs a remarkably low 0.5% energy-delay-product (EDP) overhead by activating protective measures exclusively upon detecting an attack. EQZ-LDO can detect a resistance change induced by CPA attempts as small as $1~{\Omega }$ across a wide temperature range of 0 °C–90 °C. Following detection, by leveraging the switched-capacitor-based equalizer, the DLDO automatically triggers protection to effectively equalize the current draw from the power supply, significantly attenuating the current signature, a major source of potential secret information leakage. The equalization requires only one more pair of switches than the baseline DLDO, incurring only a small area overhead. An EQZ-LDO-equipped advanced encryption standard (AES)-128 module in a 65-nm CMOS remains secure after at least 10 M-trace of CPA. Furthermore, the test vector leakage assessment (TVLA) reveals that the proposed circuits drastically reduce the t-value, an indicator of potential leakage, by $13.36{\times }$ , compared with the unprotected AES for the 10 M-trace of CPA.