Measurement of weak signal energy at acoustic frequencies by using rmshi as a passive conditioning circuit

To enable low-power recognition of slowly evolving acoustic events generated by weak acoustic sources, we investigate always-on circuit architectures for extraction of signal energy at arbitrarily selected bands of acoustic frequencies. To improve sensitivity and power consumption of existing always-on low-power acoustic event detectors, we consider the application of passive electromechanical systems. In this paper we investigate the Random Mechanical Switching Harvester on Inductor (RMSHI) for rectification of the weak sensor signal and measurement of its energy. The proof-of-concept system has been realized, functionally tested and characterized in terms of sensitivity and resolution. The sensitivity of the presented circuit is around 3 mV/nJ and the resolution is ± 0.66 nJ. The active part of the system consumes 6.3 mu mathrm{W}. The validity of the approach encourages us towards an integrated weak sensor signal measurement device, using a MEMS switch driven by the acoustic energy.