Low-Cost Structural Monitoring of Analog Circuits for Secure and Reliable Operation

The need for digital calibration due to large variations in fine-geometry processes as well as the need for performance locking mechanisms to prevent IC piracy have resulted in the prevalent use of digital assistance for analog circuits. In order to ensure the secure and reliable operation of the system, the performance of the analog circuits needs to be monitored in the field with robust, low-cost methods. In this paper, we propose a method reliant on monitoring simple invariants for detecting performance degradation of digitally-assisted analog circuits. We demonstrate the proposed method on two circuits: a low drop-out voltage regulator (LDO) and an active low-pass filter. Extensive Monte-Carlo simulations confirm that the proposed method detects deviations in performance due to tampering.