Kelly A Fitzpatrick

US Patent:

62493981, Jun 19, 2001

Filed:

Mar 4, 1998

Appl. No.:

9/034933

Inventors:

Kevin Fisher - Palo Alto CA
Kelly K. Fitzpatrick - Los Altos CA
Cory Modlin - Palo Alto CA
Ara Patapoutian - Westborough MA
Jeffrey L. Sonntag - Allentown PA
Necip Sayiner - Allentown PA

Assignee:

Maxtor Corporation - Longmont CO

International Classification:

G11B 5035

US Classification:

360 65

Abstract:

A new class of fixed partial response targets are disclosed for use in a PRML magnetic medium read channel. The preferred embodiment exhibits an equalization response characterized by the polynomial 7+4*D-4*D. sup. 2 -5*D. sup. 3 -2*D. sup. 4, where D represents the unit delay operator. This read channel target provides improved matching to the inherent magnetic channel over the known canonical class of targets (1-D)(1+D) N, and thereby reduces equalization losses. The improved spectral matching reduces amplification of noise in the channel, thereby reducing bit-error-rates. The new class of targets also exhibits a spectral null at DC, reducing problems for offset cancellation circuitry and making the disk drive less sensitive to thermal asperities. It also exhibits a spectral depression rather than a spectral null at the Nyquist frequency, making quasi-catastrophic error sequences virtually impossible. The new class of target simplifies coding and allows RLL code ratios that approach unity, improving effective recording densities, while significantly reducing BER.