Method and apparatus for adaptive gain balancing of at least one of two rotational sensors in a hard disk drive

A circuit board (38) configured for use in a hard disk drive (10), comprising:

• means for coupling to a first piezoelectric device (40) and a second piezoelectric device (42), both including a terminal (T1) and both included in said hard disk drive;
• 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 first 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.

A integrated circuit (50) configured for use in a hard disk drive (10), comprising:

• means for coupling to a first piezoelectric device (40) and a second piezoelectric device (42), both including a terminal (T1) and both included in said hard disk drive;
• a differential amplifier (60);
• an amplifier (56);
• an analog multiplexer (62);
• an analog to digital converter (64);
• and
• means for 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;
• wherein a first signal (52) is configured to couple with said terminal of said first piezoelectric device to a first of two differential inputs of said differential amplifier;
• wherein a second signal (54) is configured to couple with said terminal of said first 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.