Circuits, systems, and methods for capacitive fly height measurement

A digital storage system, comprising:

• a) a read/write head;
• b) a storage medium;
• c) a capacitive fly height measurement circuit configured to measure a capacitance between said read/write head and a surface of said storage medium, and to produce an output corresponding to said capacitance or a derive thereof, wherein said capacitive fly height measurement circuit further comprises:
• c1) an input receiving a periodic signal with a generally constant voltage slew rate, coupled to said read/write head, and
• c2) a current measuring circuit coupled to said read/write head;
• and
• d) a fly height contoller configured to adjust a distance between said read/write head and said surface in response to said output.

A method of measuring a fly height in a data storage system, wherein said fly height comprises a distance between a read/write head and a surface of a storage medium, said method comprising:

• a) measuring a capacitance between said head and said medium, including the steps of:
• a1) generating a periodic signal with a generally constant voltage slew rate and applying said periodic signal to said read/write head;
• and
• a2) measuring an electrical current at said read/write head;
• and
• b) calculating a value corresponding to said fly height from the measured capacitance.