Time-to-Digital Converter Approach to Physical Attacks on Integrated Circuits

Abstract

Shielding is an effective way of protecting the circuitry against physical attacks. Shields are metal structures that cover the top of a circuit. Measuring the delay on these shields allows detection of physical attacks. In this article, an improved time-to-digital converter (TDC) is proposed to detect these delays. This circuit relies on the phase difference between two periodic signals. These signals are generated via ring oscillators connected to the shields. The circuit, composed of the TDC, the ring oscillator, and the shield, acts like a physically unclonable function. The designs are implemented using 65 nm predictive technology model (PTM) CMOS models. The resolution of the proposed system is less than or equal to 100 fs in the whole operating range. The developed TDC exhibits the best resolution compared to other TDCs with the same technology in the literature.

Cite this article as: H. Kaydırma, A. Tangel and A. Unutulmaz, “Time-to-digital converter approach to physical attacks on integrated circuits,” Electrica, 2026, 26, 0013, doi: 10.5152/electrica.2026.25013.