摘要 |
A fly height controller circuit for a disk drive head having a resistive heater is disclosed. The fly height controller includes an error amplifier that controls a variable current source driving the resistive heater. The error amplifier compares a desired heater power signal with a feedback power signal that is generated by a multiplier. The multiplier receives a signal corresponding to the resistive heater current, for example as generated by a second variable current source also controlled by the error amplifier, and a signal corresponding to a voltage across the resistive heater. A first differential amplifier develops a differential voltage corresponding to the heater voltage. A second differential amplifier is biased by the resistive heater current signal, and receives the differential voltage form the first differential amplifier. A differential current generated by the second differential amplifier produces the feedback power signal as an output voltage.
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