Patent ID: 9678144
Date: 2017-06-13
CPC Classifications: B60R,G01H,G01R,H01L

Claim:
1. A piezoelectric or electret sensing device, comprising a piezoelectric or electret transducer for producing a measurement current in response to mechanical stimulus, and a control and evaluation circuit connected to said transducer; said control and evaluation circuit comprising a transimpedance amplifier having a first input and a second input, said transducer being operatively connected between said first input and a reference node; and an electrical waveform generator for generating an electrical waveform spectrally separated from said measurement current, said electrical waveform generator operatively connected between said second input and said reference node; said transimpedance amplifier being configured to control said first input such that a difference in electric potential between said first input and said second input be cancelled and to output an output voltage, with respect to a potential at said reference node, indicative of electrical current flowing across said transducer; wherein said control and evaluation circuit is configured to identify within said output voltage a first component of said output voltage indicative of said measurement current and a second component of said output voltage, said second component being spectrally separate from said first component and indicative of current caused by generation of said waveform; and wherein said control and evaluation circuit is configured to detect at least one of a short circuit or a broken wire based upon said second component.