Robust Implementation of Security for Analog Circuits to Prevent Malfunction

This article discusses the evolving nature of supply chain attacks, which have now shifted their focus towards targeting analog circuits because of their vulnerability to reverse engineering. The attackers' objective is to gain control over the circuit by understanding specific features or parameters, particularly the bias current of an operational amplifier and a ring oscillator. To address this security concern and prevent malfunctions, the article proposes a solution called "logic locking." This method involves integrating an encryption block with LFSR (Linear Feedback Shift Register) and a resistor switch to safeguard the operational amplifier and ring oscillator. By utilizing the encryption block's 8-bit output code and the resistor values, the relevant bias current values can be derived, thereby enabling secure and reliable circuit functioning.