A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) technology. A low-power controller IC has been fabricated in a 0.6μm CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce 8μW of usable power. The system uses a MEMS variable capacitor to convert mechanical vibration into electrical energy. The capacitor is modeled as a vibration source that couples into the electrical system through the MEMS transducer. A low-power controller directs energy conversion and supplies power to the load. The controller consists of a power electronics subsystem and a digital control core. Two energy conversion cycles are discussed: charge-constrained and voltage-constrained. The charge-constrained cycle is more efficient as it requires only a single charge source. A parallel capacitor (Cpar) is used to mimic the behavior of a voltage-constrained cycle, but increases the initial charge required. The optimal value of Cpar is determined through analysis and optimization. The MEMS device is implemented using MEMS technology, with a silicon structure etched through a deep-reactive-ion etching process. The device consists of a floating mass, folded springs, and interdigitated combs. The device is designed to resonate with a mechanical vibration source of 2520Hz. The capacitance of the device varies with the separation of the combs, affecting the energy conversion. The power electronics subsystem is designed to convert the energy from the MEMS device into usable power. The controller IC is designed to generate timing pulses for the power electronics. The controller is verified to operate correctly and its losses are measured. The system is expected to produce 8μW of usable power. The work was supported by the U.S. Army Research Laboratory and the Charles Stark Draper Lab.A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) technology. A low-power controller IC has been fabricated in a 0.6μm CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce 8μW of usable power. The system uses a MEMS variable capacitor to convert mechanical vibration into electrical energy. The capacitor is modeled as a vibration source that couples into the electrical system through the MEMS transducer. A low-power controller directs energy conversion and supplies power to the load. The controller consists of a power electronics subsystem and a digital control core. Two energy conversion cycles are discussed: charge-constrained and voltage-constrained. The charge-constrained cycle is more efficient as it requires only a single charge source. A parallel capacitor (Cpar) is used to mimic the behavior of a voltage-constrained cycle, but increases the initial charge required. The optimal value of Cpar is determined through analysis and optimization. The MEMS device is implemented using MEMS technology, with a silicon structure etched through a deep-reactive-ion etching process. The device consists of a floating mass, folded springs, and interdigitated combs. The device is designed to resonate with a mechanical vibration source of 2520Hz. The capacitance of the device varies with the separation of the combs, affecting the energy conversion. The power electronics subsystem is designed to convert the energy from the MEMS device into usable power. The controller IC is designed to generate timing pulses for the power electronics. The controller is verified to operate correctly and its losses are measured. The system is expected to produce 8μW of usable power. The work was supported by the U.S. Army Research Laboratory and the Charles Stark Draper Lab.