Patent ID: 7864483

Claim:
A hard disk drive, comprising: a first piezoelectric device ( 40 ) and a second piezoelectric device ( 42 ), both including a terminal (T 1 ); and a circuit board ( 38 ) coupled to first piezoelectric device and to said second piezoelectric device, with said circuit board including the configuration of a differential amplifier ( 60 ), an amplifier ( 56 ), an analog multiplexer ( 62 ), an analog to digital converter ( 64 ) and a processor ( 70 ) communicating a gain control ( 80 ) to said amplifier, a multiplexer control ( 82 ) to said analog multiplexer and receiving a sampled signal ( 84 ) from said analog to digital converter; a first signal ( 52 ) coupling said terminal of said first piezoelectric device to a first of two differential inputs of said differential amplifier; a second signal ( 54 ) coupling said terminal of said second piezoelectric device to an input of said amplifier to create an amplified second signal ( 57 ) coupled to a second of said differential inputs of said differential amplifier to create a difference signal ( 58 ) received by said analog multiplexer along with said first signal and said second signal to create a selected analog signal ( 66 ) presented to said analog to digital converter to create said sampled signal.