Circuitry, systems, and methods for measuring the fly height of a
read/write head in a magnetic data storage system. The circuitry
generally includes a capacitance measurement circuit configured to
measure the capacitance between the read/write head and the surface of
the magnetic recording medium (or a derivative of that capacitance), and
a fly height converter configured to produce an output signal
corresponding to the fly height based on the measurement. The capacitance
measurement circuit is generally configured to receive a periodic signal
with a generally constant voltage slew rate coupled to the read/write
head. The present invention advantageously provides for electronically
measuring the fly height of a read/write head in situ in a magnetic
storage system. The sensed fly height may then be used by the system to
control fly height actuation.