Self-generating SC-conditioning circuit for autonomous sensors

In this paper a self-generating conditioning circuit based on Switched Capacitor (SC) implemented by using mechanical transducers driven by vibrations has been developed. The proposed conditioning circuit is based on piezoelectric elements and magnetically-coupled cantilevers having each one an anti-symmetric (180° of phase shift) bistable behavior in order to implement SC topologies. In particular the configuration here presented implements a 1^st-order low-pass filter used as conditioning circuit which can, at the same time, harvests the energy coming from vibrations. The solution is suitable to be used as sustainer of autonomous sensor nodes. It is worth noting that the presented approach has been used here to implement integrated filters having several attractive features such as: low frequency applications, low leakage switches having galvanic isolation, low noise architectures, simple driving device and able to recovery energy coming from ambient vibrations. The system has been analytically modeled, simulated and an experimental campaign has been performed obtaining very intriguing results.