Insights into tunnel FET-based charge pumps and rectifiers for energy harvesting applications

In this paper, the electrical characteristics of tunnel field-effect transistor (TFET) devices are explored for energy harvesting front-end circuits with ultralow power consumption. Compared with conventional thermionic technologies, the improved electrical characteristics of TFET devices are expected to increase the power conversion efficiency of front-end charge pumps and rectifiers powered at sub-µW power levels. However, under reverse bias conditions the TFET device presents particular electrical characteristics due to its different carrier injection mechanism. In this paper, it is shown that reverse losses in TFET-based circuits can be attenuated by changing the gate-to-source voltage of reverse-biased TFETs. Therefore, in order to take full advantage of the TFETs in front-end energy harvesting circuits, different circuit approaches are required. In this paper, we propose and discuss different topologies for TFET-based charge pumps and rectifiers for energy harvesting applications.Peer ReviewedPostprint (author's final draft

A battery-less, self-sustaining RF energy harvesting circuit with TFETs for µW power applications

This paper proposes a Tunnel FET (TFET) power management circuit for RF energy harvesting applications. In contrast with conventional MOSFET technologies, the improved electrical characteristics of TFETs promise a better behavior in the process of rectification and conversion at ultra-low power (µW) and voltage (sub-0.25 V) levels. RF powered systems can not only benefit from TFETs in front-end rectifiers by harvesting the surrounding energy at levels where conventional technologies cannot operate but also in the minimization of energy required by the power management circuit. In this work we present an energy harvesting circuit for RF sources designed with TFETs. The TFET controller emulates an adequate impedance at the output of the rectifier in order to allow maximum transfer of power from the RF source to the input of the boost converter. The output load is activated once the output capacitor reaches a voltage value of 0.5 V. The results show an efficiency boost of 89 % for an output load consuming 1 µW with an available RF power of -25 dBm.Postprint (published version

Design of Adiabatic MTJ-CMOS Hybrid Circuits

Low-power designs are a necessity with the increasing demand of portable devices which are battery operated. In many of such devices the operational speed is not as important as battery life. Logic-in-memory structures using nano-devices and adiabatic designs are two methods to reduce the static and dynamic power consumption respectively. Magnetic tunnel junction (MTJ) is an emerging technology which has many advantages when used in logic-in-memory structures in conjunction with CMOS. In this paper, we introduce a novel adiabatic hybrid MTJ/CMOS structure which is used to design AND/NAND, XOR/XNOR and 1-bit full adder circuits. We simulate the designs using HSPICE with 32nm CMOS technology and compared it with a non-adiabatic hybrid MTJ/CMOS circuits. The proposed adiabatic MTJ/CMOS full adder design has more than 7 times lower power consumtion compared to the previous MTJ/CMOS full adder

TFET-Based power management circuit for RF energy harvesting

This paper proposes a Tunnel FET (TFET)-based power management circuit (PMC) for ultra-low power RF energy harvesting applications. In contrast with conventional thermionic devices, the band-to-band tunneling mechanism of TFETs allows a better switching performance at sub-0.2 V operation. As a result, improved efficiencies in RF-powered circuits are achieved, thanks to increased rectification performance at low power levels and to the reduced energy required for a proper PMC operation. It is shown by simulations that heterojunction TFET devices designed with III-V materials can improve the rectification process at received power levels below -20 dBm (915 MHz) when compared to the application of homojunction III-V TFETs and Si FinFETs. For an available power of -25 dBm, the proposed converter is able to deliver 1.1 µW of average power (with 0.5 V) to the output load with a boost efficiency of 86%.Postprint (author's final draft