This article introduces the energy harvesting technology for wireless communication instrumentation, monitoring, and control applications. By collecting environmental energy sources such as mechanical vibration, temperature differential, and incident light, the devices can operate continuously without grid connection and with minimal maintenance. Linear Technology offers power management solutions to address the challenges of harvesting ambient low energy sources, including LTC3588 for vibration sources, LTC3108/LTC3109 for thermal sources, and now LTC3105 for photovoltaic energy harvesting applications.