Detecting Malfunction of Bias Current for Operational Amplifiers

Supply chain attacks have evolved from being limited to digital circuitry to now attacking analog circuits since they are easier to reverse engineer. Hackers who know one or two circuit characteristics or parameters can determine the key. The aim of this paper is to accomplish logic locking on analog ICs, locate vulnerabilities, and exploit them for some known analog circuits, causing the circuit to malfunction. The objective is to find or extract a key which enables the circuit to function suitably. This is achieved through performing logic locking on an operational amplifier using an encoder and a resistor switch. The corresponding bias current values are determined based on the 4-bit output code from the encoder and the value of the resistors, and the requisite gain and cutoff frequency can be obtained.