System and method for disk drive fly height measurement

A system for determining a fly height, the system comprising:

• a first front end circuit coupled to a head of a disk drive, the first front end circuit comprising a selection circuit and a conversion circuit coupled to the selection circuit, the first front end circuit being configured to:
• determine a first differential voltage between the head and a reference voltage;
• and
• convert the first differential voltage to a first analog current signal with the conversion circuit;
• a first back end circuit coupled to the first front end circuit, the first back end circuit being configured to:
• convert the first analog current signal to a second differential voltage;
• and
• measure a first capacitance between the head and a disk of the disk drive using the second differential voltage;
• and
• a logic device coupled to the first back end circuit, the logic device being configured to determine the fly height between the head and the disk using the measurement of the first capacitance.

A system for determining a fly height, the system comprising:

• a first front end circuit coupled to a first head of a disk drive, the first front end circuit being configured to produce a first analog current signal;
• a second front end circuit coupled to a second head of the disk drive, the second front end circuit being configured to produce a second analog current signal;
• a first back end circuit coupled to the first front end circuit, the first back end circuit being configured to measure a first capacitance between the first head and a first disk of the disk drive using the first analog current signal;
• a second back end circuit coupled to the second front end circuit, the second back end circuit being configured to measure a second capacitance between the second head and a second disk of the disk drive using the second analog current signal;
• and
• a logic device coupled to the first back end circuit and the second back end circuit, the logic device being configured to:
• correct a measurement of the first capacitance using the measurement of the second capacitance;
• and
• determine the fly height between the first head and the first disk using the corrected measurement of the first capacitance.