To address the productivity bottlenecks in power analysis and optimization of modern systems, we propose to treat power as a signal and leverage the rich set of signal processing techniques. We first investigate the power signal properties of digital systems and analyze their limitations. We then study signal processing techniques for detecting temporal and structural correlations of power signals. Finally, we employ these techniques to accelerate the simulation of an architecture-level power simulator. Our experiments with SPEC2000 show that we can speed up the simulation by 100X without introducing significant errors at various resolution levels. Categories and Subject Descriptors: J.6 [Computer- Aided Engineering]: Computer-aided design (CAD) General Terms: Algorithms, Design