Hardware trojan state detection for analog circuits and systems

The circuit structures with positive feedback loops are likely to have multiple operating points, and the unwanted Trojan state is easy to be triggered by process, voltage, and temperature variation or user´s action. In this paper, circuit-level Homotopy methods are used to find all operating points and detect Trojan states. Furthermore, the temperature characteristic of the positive feedback loop circuits can also identify the Trojan state. Examples are given to show both Homotopy and temperature methods are valid.