Anti-Counterfeiting Secured Design of a Bandgap Reference Circuit

Integrated circuit (IC) piracy and counterfeiting are a major preoccupation threat for IC designers. A powerful defense is IC locking which consists in making the IC functionality dependent on a digital key. In this work, we propose to simultaneously lock indirectly all analog and mixed-signal blocks of an IC via locking the bandgap reference (BGR) circuits that provide their biasing or reference currents or voltages. We demonstrate an obfuscated BGR in the 22nm FDSOI technology by GlobalFoundries featuring a 24-bit single secret key. Obfuscation shows no performance penalty for the valid key and less than 10% area overhead compared to the unsecured design, while guaranteeing high functionality corruption for invalid keys. The proposed obfuscation shows strong resilience against all known counter-attacks in the analog domain.