The pursuit of continuous scaling of electronic devices in the semiconductor industry has led to two unintended but significant outcomes: a rapid increase in susceptibility to radiation induced errors, and an overall rise in power consumption. Operating under low voltage to reduce power only aggravates radiation related reliability issues. The proposed "SEU Hardening Incorporating Extreme Low Power Bitcell Design" (SHIELD) addresses these two major concerns simultaneously. It is based on the concept of gating the conventional cross-coupled inverters while introducing a novel "cut-off" network. This creates redundant storage nodes and eliminates the internal feedback loop during radiation particle impact. The SHIELD bitcell tolerates upsets with charge deposits over 1 pC. Simulations confirm its advantages in terms of leakage power, with more than twofold lower leakage currents than previous solutions when operated at a 700 mV supply voltage in a 65 nm process. To validate the bitcell's robustness, several test cases and special concerns, including multiple node upsets (MNU) and half-select, are examined.
Side-channel attacks constitute a concrete threat to IoT systems-on-a-chip (SoCs). Embedded memories implemented with 6T SRAM macrocells often dominate the area and power consumption of these SoCs. Regardless of the computational platform, the side-channel sensitivity of low-hierarchy cache memories can incur significant overhead to protect the memory content (i.e., data encryption, data masking, etc.). In this manuscript, we provide a silicon proof of the effectiveness of a low cost side-channel attack protection that is embedded within the memory macro to achieve a significant reduction in information leakage. The proposed solution incorporates low-cost impedance randomization units, which are integrated into the periphery of a conventional 6T SRAM macro in fine-grain memory partitions, providing possible protection against electromagnetic adversaries. Various blocks of unprotected and protected SRAM macros were designed and fabricated in a 55 nm test-chip. The protected ones had little as 1% area overhead and less than 5% performance and power penalties compared to a conventional SRAM design. To evaluate the security of the proposed solution, we applied a robust mutual information metric and an adaptation to the memory context to enhance this evaluation framework. Assessment of the protected memory demonstrated a significant information leakage reduction from 8 bits of information exposed after only 100 cycles of attack to less than ∼1.5 bits of mutual information after 160K traces. The parametric nature of the protection mechanisms are discussed while specifying the proposed design parameters. Overall, the proposed methodology enables designs with higher security-level at a minimal cost.
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