In this paper, we suggest that the dynamic power dissipation of a circuit can be used to detect faults in it. The change in dissipation caused by a fault can be maximized by applying specific test vectors. For example circuits, we show that the power dissipation can be used to detect faults which do not affect static power dissipation. We also discuss how faults may be detected with a frequency domain analysis. In many cases, the Fourier spectra of the power supply currents in the good and faulty circuits will be very different. Power monitoring is also verified experimentally, for an example circuit. 1 Introduction Monitoring the current drawn from the power supply is one method to test a CMOS circuit [2--4]. In this paper, we demonstrate that monitoring the dynamic power dissipation of a device can also aid in fault detection. A fault which affects functionality also changes the energy consumption on input transitions. The inputs can be applied so as to maximize the difference in e...