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The superior electrical characteristics of the heterojunction III-V Tunnel FET (TFET) devices can outperform current\ud technologies in the process of energy harvesting conversion at ultra-low power supply voltage operation (sub-0.25 V). In this work, it is\ud shown by simulations that a cross-coupled switched-capacitor topology with GaSb-InAs TFET devices present better conversion\ud performance compared to the use of Si FinFET technology at low temperature variations\ud (¿T < 3 ºC) when considering a thermo-electric energy harvesting source (with a = 80 mV/K). At higher ¿T, the conversion process is\ud degraded with the increase of the transistor losses. Considering a ¿T of 1 ºC (2 ºC), one cross-coupled stage with TFET devices can\ud achieve 74 % (69 %) of power conversion efficiency when considering an output load of 0.4 µA (6 µA). At the same conditions, the\ud FinFET charge pump is shown inefficient.Postprint (published version

Abstract-Compared to conventional technologies, the superior electrical characteristics of III-V Tunnel FET (TFET) devices can highly improve the process of energy harvesting conversion at ultra-low input voltage operation (sub-0.25V). In order to extend the input voltage/power range of operation in conventional charge pump topologies with TFET devices, it is of the major importance to reduce the band-to-band tunneling current when the transistor is under reverse bias conditions. This paper proposes a new charge pump topology with TFET devices that attenuate the reverse losses, thus improving the power conversion efficiency (PCE) in a broader range of input voltage values and output loads. It is shown by simulations that compared with the conventional gate cross-coupled charge pump and considering an input voltage of 640 mV, the proposed topology reduces the reverse losses from 19 % to 1 %, for an output current of 10 µA. For this case, the PCE increased from 63 % to 83 %.

Abstract-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.

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