This book introduces the origin of biomedical signals and the operating principles behind them and introduces the characteristics of common biomedical signals for subsequent signal measurement and judgment. Since biomedical signals are captured by wearable devices, sensor devices, or implanted devices, these devices are all battery-powered to maintain long working time. We hope to reduce their power consumption to extend service life, especially for implantable devices, because battery replacement can only be done through surgery. Therefore, we must understand how to design low-power...