LDO-based Odometer to Combat IC Recycling

Recycled counterfeit integrated circuits (ICs) are used chips that were removed from discarded electronics and resold in the market as new. Recycled ICs are prone to early failure and serve as a threat to reliability which can be very dangerous if found in critical applications. Although recycled IC detection methods have been researched, there lacks a solution that serves for every chip type and scenario specifically analog and mixed signal (AMS) system-on-chips (SoCs). For example, hardware security primitives have been primarily developed for digital circuits but cannot be directly ported to AMS chips. AMS primitives need to maintain security and reliability along with stringent constraints on area, power, pins, clock, etc. In our prior work, we experimentally studied low-dropout regulator (LDO) aging and resulting power supply rejection ratio (PSRR) degradation. While initial results for standalone LDOs were promising, the results for LDOs embedded in SoCs could be improved. In this paper, we propose a new LDO design that partially re-purposes the already existing LDO in the chip, study its aging effects, and optimize its sensitivity for better recycled chip detection. Since LDOs are often embedded in the power management circuitry in nearly all types of ICs, this solution can function as a lightweight, one-size-fits-all approach for detecting recycled analog/mixed-signal and digital SoCs.