This paper presents a fully autonomous power converter IC for energy harvesting from multiple and multi-type sources such as piezoelectric, photovoltaic, thermoelectric and RF transducers. The converter performs an independent selfadapting input power tracking process for each source. The peak power conversion efficiency measured during single-source operation is 89.6%. With all sources enabled, the intrinsic current consumption is as low as 47.9 nA/source. A self-starting battery-less architecture has been implemented in a 0.32 µm STMicroelectronics BCD technology with a 2142 µm x 2142 µm die area. The IC only requires a single shared inductor and an external storage capacitor for the basic working configuration. With respect to other multi-source energy harvesters, this design specifically introduces a series of nano-power design techniques for extreme minimization of the intrinsic consumption during operation. The small chip size combined with the limited number of required external component, the high conversion efficiency, and the state-of-the-art intrinsic nano-current consumption make the IC suitable for many critical applications with very limited available power such as wearable devices or unobtrusive wireless sensor networks.
We present a self-sustained battery-less multi-sensor platform with RF harvesting capability down to −17 dBm and implementing a standard DASH7 wireless communication interface. The node operates at distances up to 17 m from a 2 W UHF carrier. RF power transfer allows operation when common energy scavenging sources (e.g., sun, heat, etc.) are not available, while the DASH7 communication protocol makes it fully compatible with a standard IoT infrastructure. An optimized energy-harvesting module has been designed, including a rectifying antenna (rectenna) and an integrated nano-power DC/DC converter performing maximum-power-point-tracking (MPPT). A nonlinear/electromagnetic co-design procedure is adopted to design the rectenna, which is optimized to operate at ultra-low power levels. An ultra-low power microcontroller controls on-board sensors and wireless protocol, to adapt the power consumption to the available detected power by changing wake-up policies. As a result, adaptive behavior can be observed in the designed platform, to the extent that the transmission data rate is dynamically determined by RF power. Among the novel features of the system, we highlight the use of nano-power energy harvesting, the implementation of specific hardware/software wake-up policies, optimized algorithms for best sampling rate implementation, and adaptive behavior by the node based on the power received.
This paper presents the nanopower design of an integrated 1 µW-to-5 mW power management circuit. The circuit integrates a boost converter with maximum power point tracking, a low drop-out voltage regulator (LDO), and a start-up circuit for battery-less activation from discharged states. The IC implements a dynamic two-way power routing policy that ensures a fast start-up from discharged states even with very large energy storage capacitors. In order to reduce the intrinsic power, asynchronous control logic was adopted. The circuit was implemented in a STMicroelectronics 0.32 µm microelectronic technology. The power conversion section and the LDO draw respectively stand-by currents of 121 nA and 414 nA in the active modes. The circuit achieves a peak conversion efficiency of 77.1% and a minimum start-up voltage of 223 mV. where he has been involved in energy harvesting systems, micropower electronics, and CMOS design.
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