# Energy Management Integrated Circuit for Multi-Source Energy Harvesters in WBAN Applications
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[PERSON]  
2 SoC Design and Research Group, Intelligent SoC Research Department, Electronics and Telecommunications Research Institute, Daejeon 34129, Korea; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (K.-I.O. ); [EMAIL_ADDRESS] (M.J.P. ); [EMAIL_ADDRESS] (H.-I.P. ); [EMAIL_ADDRESS] (I.G.L. ); [EMAIL_ADDRESS] (J.-J.L.) 1  
[PERSON]  
2 SoC Design and Research Group, Intelligent SoC Research Department, Electronics and Telecommunications Research Institute, Daejeon 34129, Korea; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (K.-I.O. ); [EMAIL_ADDRESS] (M.J.P. ); [EMAIL_ADDRESS] (H.-I.P. ); [EMAIL_ADDRESS] (I.G.L. ); [EMAIL_ADDRESS] (J.-J.L.) 1  
[PERSON]  
2 SoC Design and Research Group, Intelligent SoC Research Department, Electronics and Telecommunications Research Institute, Daejeon 34129, Korea; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (K.-I.O. ); [EMAIL_ADDRESS] (M.J.P. ); [EMAIL_ADDRESS] (H.-I.P. ); [EMAIL_ADDRESS] (I.G.L. ); [EMAIL_ADDRESS] (J.-J.L.) 1  
[PERSON]  
2 SoC Design and Research Group, Intelligent SoC Research Department, Electronics and Telecommunications Research Institute, Daejeon 34129, Korea; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (K.-I.O. ); [EMAIL_ADDRESS] (M.J.P. ); [EMAIL_ADDRESS] (H.-I.P. ); [EMAIL_ADDRESS] (I.G.L. ); [EMAIL_ADDRESS] (J.-J.L.) 1  
[PERSON]  
2 SoC Design and Research Group, Intelligent SoC Research Department, Electronics and Telecommunications Research Institute, Daejejeon 34129, Korea; [EMAIL_ADDRESS] (T.K. ); [EMAIL_ADDRESS] (K.-I.O. ); [EMAIL_ADDRESS] (M.J.P. ); [EMAIL_ADDRESS] (H.-I.P. ); [EMAIL_ADDRESS] (I.G.L. ); [EMAIL_ADDRESS] (J.-J.L.) 13 July 2018
to micro watts [8], and this is insufficient to drive wearable electronic devices. A micro watt of harvested power is generally regarded as useless in electronic devices, and conventional energy management research has been focused on extracting more power from energy harvesters by matching impedance. Unfortunately, with micro watt power harvesters, the method of extracting more power with complex algorithms is not helpful to increase the power output. Rather, the power required to extract output power may be greater than the potential for increase in the output power. Therefore, in WBAN applications, the algorithm approach for extracting more power is not appropriate. Instead of extracting more power from an individual energy harvester, combining energy from multi-source energy harvesters is more worthwhile. The most common conventional structure for combining energy is the diode-based power OR-ing method [9; 10; 11], which is also the simplest way to combine energy from multiple sources. However, this approach has one drawback: unwanted power consumption caused by a forward voltage drop on the diode. Recently, to avoid waste of power in the diode based OR-ing circuit, an active switch can be used in place of a diode. An active switch can resolve the problem of the forward voltage drop, although it introduces a new issue of power consumption. In designing energy combining circuits for WBAN applications [12; 13; 14; 15], power consumption is one of the most important issues. As mentioned, the power from each energy harvester is limited to micro watts, and the energy combining circuit has to consume less power than the power harvested. If the combining circuit consumes more power than that harvested, no energy can be supplied to the wearable devices. To reduce power consumption, the energy combining circuit should be simple in structure and guided by an algorithm. In energy harvesting circuits, there is one more issue to be considered. In addition to power consumption issue, the circuit also has to manage a wide range of harvested-energy levels. The amount of harvested energy varies according to the environmental conditions under which each specific harvesting transducer operates [16]. Therefore, the energy management circuit should handle a wide range of harvest-energy levels.