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Switchable Gain Read Amplifier

IP.com Disclosure Number: IPCOM000085097D
Original Publication Date: 1976-Feb-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Sensenbaugh, JD: AUTHOR [+2]

Abstract

The linear amplifier 10 receiving the output of a magnetic read head 12 traversing magnetic disk 14 has its gain switched as head 12 passes across intermediate track B, so that the output VO of linear amplifier 10 is less than a given maximum value when head 12 is on the outermost track A, and is above some minimum value when head 12 is on the innermost track C.

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Switchable Gain Read Amplifier

The linear amplifier 10 receiving the output of a magnetic read head 12 traversing magnetic disk 14 has its gain switched as head 12 passes across intermediate track B, so that the output VO of linear amplifier 10 is less than a given maximum value when head 12 is on the outermost track A, and is above some minimum value when head 12 is on the innermost track C.

The read head 12 output voltage VH increases with increasing track radius r. Thus as head 12 moves from track C to track A, the output voltage VH continuously increases. The read head output voltage VH is amplified by linear amplifier 10 to produce the amplifier output voltage VO. The amplifier gain must be maintained below some maximum when head 12 is on track A, so that the dynamic range of the amplifier and other system parameters are not exceeded.

When head 12 moves to track C, some minimum head output voltage VH is required to produce a sufficient minimum amplifier output voltage VO. This minimum head output voltage VH, may be reduced by increasing the gain of amplifier 10 at some intermediate track B. This is accomplished by closing switches 16 and 18 as head 12 crosses track B moving inwardly.

The gain amplifier 10 is inversely proportional to the impedance looking out of amplifier 10 at ports X and Y. The resistor-capacitor network illustrated in Fig. 1 is connected to ports X and Y of amplifier 10 via switches 16 and 18.

If the capacitors and resistors of this netwo...