Semi-passive Enhancement of Sensitivity of Piezoelectric Acoustic Sensor with Negative Impedance Matching Circuit

New semi-passive negative impedance matching technology is put forward to enhance the sensitivity of piezoelectric acoustic sensor at low frequencies; what's more, the bandwidth of high sensitivity is very broad. Mason electro-mechanical equivalent model of piezoelectric acoustic sensor is established and analyzed. Based on impedance matching theory, the parameters of matching circuit are obtained. The sensitivity of this semi-passive piezoelectric sensor with the proper parameters can even exceed that of no matching circuit over 20 dB in broad band of low frequency. It is validated by experimental measurements.