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Write-to-servo common mode DC offset recovery accelerator, after AE-channel DC blocking capacitor

IP.com Disclosure Number: IPCOM000014763D
Original Publication Date: 2000-Jul-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 28K

Publishing Venue

IBM

Abstract

External low impedance network by pull-up(down) resistors, is prepared at input of read/write circuit channel module IC to accelerate common mode DC offset recovery after write operation.

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  Write-to-servo common mode DC offset recovery accelerator, after AE-channel DC blocking capacitor

    External low impedance network by pull-up(down) resistors, is prepared at
input of read/write circuit channel module IC to accelerate common mode DC offset
recovery after write operation.

In read signal pass between AE amplifier and channel, usually DC blocking
capacitors are used to adjust DC level for channel input stage.

New level is given by charge / discharge current from channel internal pull-up
resister or internal current source.

If AE amplifier has DC offset between write and read mode, and in case that read
operation starts just after write (read servo between write operation), DC level
cannot be adjusted fully and that results in servo failure such as ID error or
bad positioning by wrong wedge amplitude.

To prevent this situation, external low impedance network by pull-up(down)
resistors, resister * in figure-1, is attached to help charge / discharge speed.

Figure-1

AE out (+) -----||-----+----- channel in (+)

|

resistor *

|

Vcc (low Z)

|

resistor *

|

AE out (-) -----||-----+----- channel in (-)

1