Paul H Francois

US Patent:

52819310, Jan 25, 1994

Filed:

Oct 8, 1992

Appl. No.:

7/957853

Inventors:

James A. Bailey - Tucson AZ
Paul H. Francois - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H03G 1104
H04B 304

US Classification:

333 171

Abstract:

An on-chip apparatus and method are provided for automatically tuning a continuous time filter in which a single filter selectively filters an information signal or, when tuning is desired, an unfiltered reference signal. During tuning, a controller determines the amplitudes of the unfiltered and filtered reference signals and their ratio. From the ratio, the controller ascertains a corresponding center or tuned frequency of the filter. If the ascertained frequency does not substantially equal a desired tuned frequency, the controller directs a bias controller to adjust the bias of the filter until the tuned frequency is substantially equal to the desired tuned frequency.

US Patent:

54426189, Aug 15, 1995

Filed:

Nov 12, 1993

Appl. No.:

8/150896

Inventors:

Anthony G. Dewey - San Jose CA
Paul H. Francois - Tucson AZ
Timothy S. Gardner - Tucson AZ
Hideaki Iwasaki - Fujisawa, JP
Morovat Tayefeh - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 700

US Classification:

369124

Abstract:

An optical drive provides an internal routine for automatically optimizing the common mode rejection ratio of the magneto-optic data output signal. A microprocessor provides control to a controller module which in turn supplies a plurality of calibration signals to a data detecting portion. The calibration signals modify predetermined parameters of the data detecting portion based upon measuring a predetermined parameter indicative of the common mode rejection ratio. The common mode rejection ratio optimization corrects for mismatches in both the optical elements and in the electronic data circuits.

US Patent:

53092953, May 3, 1994

Filed:

Oct 8, 1992

Appl. No.:

7/957858

Inventors:

James A. Bailey - Tucson AZ
Paul H. Francois - Tucson AZ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 503
G11B 509
G11B 502

US Classification:

360 66

Abstract:

A method and apparatus are provided for biasing a non-center tapped magneto-resistive head at a constant voltage using two separate biasing stages to provide independent control over the voltage at each of the two terminals of the head. A first control device detects the voltage at a first head terminal and directs changes to the output of a current source, interconnected with a first terminal of the head, to maintain the voltage at the first terminal at a first predetermined voltage. A second control device detects the voltage at second terminal of the head and directs changes to the input of a current sink, interconnected with the second terminal, to maintain the voltage at the second terminal at a second predetermined voltage. Each control device is interconnected to a separate reference voltage source; by appropriate selection of the voltages of the reference voltage sources, the voltages at the two head terminals and the potential across the head can be established and maintained.