DC-offset adjustment for balanced embedded contact sensor
AssigneeHGST Netherlands B.V.
InventorsJohn Contreras, Samir Y. Garzon, Rehan Ahmed Zakai
Life of this patent
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Abstract
Embedded contact sensor controls for use in arm electronics (AE) in a disk drive are described that provide for removing undesirable offsets between the measured voltage across the ECS resistor in the slider and the balance resistor in ECS amplifier in the arm electronics (AE), which allows increased amplification of the resulting adjusted signal without saturation. Embodiments include a Zero-Offset Circuit, which can be activated periodically or on demand to sample and hold the present DC offset voltage in the ECS amplifier signal and subtract the DC offset voltage from ECS amplifier signal. The adjusted signal can then be further amplified without saturation.
Claims20
A disk drive comprising:
- a slider with an embedded contact sensor with a first resistance electrically connected to an embedded contact sensor amplifier circuit;
- and
- the embedded contact sensor amplifier circuit including a second resistance and producing an adjusted output signal indicative of a difference between the first resistance and a second resistance with a selected DC component removed.
A disk drive comprising:
- a slider with an embedded contact sensor with a first resistance electrically connected to an arm electronics chip;
- a balancing preamplifier in the arm electronics chip that produces a first output signal indicative of a difference between the first resistance and a second resistance in the balancing preamplifier;
- and
- a zero-offset circuit that includes a unity gain differential amplifier the first output signal being a positive input and a negative input being a DC signal generated by a sample and hold circuit that is connected to a low pass filter connected to an output of the unity gain differential amplifier, whereby a trigger signal to the sample and hold circuit results in a DC voltage output of the low pass filter being sampled and held and fed to the negative input of the unity gain differential amplifier until a subsequent trigger signal occurs.
A method of operating a disk drive having a slider with an embedded contact sensor with a first resistance comprising:
- generating a first output signal indicative of a difference between the first resistance and a second resistance in a preamplifier;
- and
- removing a selected DC voltage from the first output signal to generate an adjusted output signal, the selected DC voltage being determined when a trigger signal is sent to an embedded contact sensor circuit in an arm electronics chip, the embedded contact sensor circuit responding to the trigger signal by sampling and holding a DC voltage in a low pass filtered signal derived from the first output signal and generating the adjusted output signal with the DC voltage removed until a subsequent trigger signal occurs.
Dependencies are inferred from the claim text.