An adaptive impedance tracking frontend for inductively powered body sensor nodes

In this paper, an adaptive impedance tracking front end for inductively powered body sensor node is presented. By implementing a novel impedance matching network with digitally tunable capacitor array in an inductively powered energy hsarvester chip, the system can adaptively maintain impedance match with the coil under influences from nearby human body or metal object, deformation and in homogeneity from manufacture. The experiment demonstrates that the system can effectively maintain resonant frequency of the receiver antenna, boost resonance amplitude of coil and rectifier output significantly compared with fixed matching networks in on-body application.