Robert J Swartz

US Patent:

47916281, Dec 13, 1988

Filed:

Oct 16, 1987

Appl. No.:

7/109009

Inventors:

Robert G. Swartz - Tinton Falls NJ

Assignee:

American Telephone and Telegraph Company, AT&T Bell Labs - Murray Hill NJ

International Classification:

H04J 302

US Classification:

370112

Abstract:

A demultiplexer for demultiplexing a multiplexed input data signal into M output channels using M sequencer means clocked from an overlapping M phase system clock. The system clock operates at a frequency equal to the input data signal rate divided by M. Each sequencer means is clocked by a unique combination of the M phase system clock signals to select one data channel from the multiplexed input data signal. Since all sequencer means circuits are synchronized to the system clock, no variable delay lines are needed to align the timing between the circuit stages. A time delay latch is provided where needed in each sequencer means to enable all channels to output data concurrently. The demultiplexer includes a real-time data-framing capability to assure that the input data is correctly mapped to the proper output channels.

US Patent:

46808108, Jul 14, 1987

Filed:

Jun 28, 1985

Appl. No.:

6/749746

Inventors:

Robert G. Swartz - Highlands NJ

Assignee:

American Telephone and Telegraph Company, AT&T Bell Labs - Murray Hill NJ

International Classification:

H04B 900

US Classification:

455609

Abstract:

The novel technique for stabilizing an electronic device, e. g. , a semiconductor laser, is disclosed. The technique can advantageously be used to stabilize the bias current of such a laser at or near the lasing threshold of the device. A preferred application of thus stabilized lasers is in optical communication systems. The inventive technique comprises determination of a derivative of a variable characteristic of the device operation, e. g. , the voltage across a laser, with respect to a parameter, e. g. , the laser bias current. The derivative is determined by a novel method. For the particular case of laser bias stabilization, the method comprises injecting one or more nonsinusoidal ac current components into the laser, and phase-sensitivity detecting the voltage changes at the ac frequencies. The method can, in principle, be used to determine derivatives of arbitrarily high order. A circuit capable of determining the second, third and fourth derivatives of the voltage as a function of bias current is disclosed.

US Patent:

47899840, Dec 6, 1988

Filed:

Oct 16, 1987

Appl. No.:

7/109122

Inventors:

Robert G. Swartz - Tinton Falls NJ

Assignee:

American Telephone and Telegraph Company, AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H04J 302

US Classification:

370112

Abstract:

A high data rate multiplexer (MUX) architecture includes front-end and rear-end MUXs clocked at a system clock rate equal to one-half of the MUX output data rate. The front-end MUX selects inputs under control of select signals derived from multiple phases of a select clock. The select clock is derived from the system clock. The number of select signals is equal to the multiplexing factor of the MUX.

US Patent:

44281110, Jan 31, 1984

Filed:

Dec 7, 1981

Appl. No.:

6/327790

Inventors:

Robert G. Swartz - Highlands NJ

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H01L 21203
H01L 21302

US Classification:

29576E

Abstract:

A process for fabricating a high speed bipolar transistor is described wherein the collector, base and emitter layers are first grown using molecular beam epitaxy (MBE). A mesa etch is performed to isolate a base-emitter region, and a contact layer is grown using MBE over this isolated region to make contact with the thin base layer. The contact layer is selectively etched to expose the emitter layer, and metal is deposited to fabricate emitter, base and collector contacts.

US Patent:

50273620, Jun 25, 1991

Filed:

Dec 29, 1988

Appl. No.:

7/291899

Inventors:

John L. Hokanson - Upper Milford Township, Lehigh County PA
Robert G. Swartz - Tinton Falls NJ

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H01S 300

US Classification:

372 38

Abstract:

A laser biasing stabilization circuit and method uses the second derivative of the optical light output of a laser with respect to the current through the laser, d. sup. 2 L/dI. sup. 2, in a feedback loop to control the laser bias current through the laser. The modulation current in the laser is controlled using a second, average power feedback loop.

US Patent:

51914620, Mar 2, 1993

Filed:

May 11, 1990

Appl. No.:

7/534623

Inventors:

Richard D. Gitlin - Little Silver NJ
Sanjay Kasturia - Red Bank NJ
Robert G. Swartz - Tinton Falls NJ
Jack H. Winters - Middletown NJ

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H04B 1006

US Classification:

359189

Abstract:

Signal distortion in fiber optic systems is compensated for by forming decisions as to the transmitted information as a joint function of the received signal and of a feedback signal. The latter, in turn, is a function of decisions made for at least one signal transmitted over the fiber. The feedback signal determines the value of a threshold to which the received signal is compared in order to generate the decisions.

US Patent:

43859461, May 31, 1983

Filed:

Jun 19, 1981

Appl. No.:

6/275418

Inventors:

Sean N. Finegan - Aberdeen NJ
James H. McFee - Colts Neck NJ
Robert G. Swartz - Highlands NJ
Alexander M. Voshchenkov - Freehold NJ

Assignee:

Bell Telephone Laboratories, Incorporated - Murray Hill NJ

International Classification:

H01L 21203
H01L 21263

US Classification:

148175

Abstract:

A molecular beam epitaxial method of fabricating a semiconductor device is disclosed wherein the dopant is implanted by establishing a plasma containing ions of the dopant and the ions are coupled through a drift chamber to impinge on the growing substrate surface. The plasma formed in the ion gun has ions of boron and arsenic and therefore the dopants selected for implantation can be determined by setting a mass filter present in the ion gun. A change to the dopant of the opposite conductivity type can be accomplished in seconds by simply readjusting the mass filter in the ion gun.

US Patent:

44928521, Jan 8, 1985

Filed:

Feb 11, 1983

Appl. No.:

6/465800

Inventors:

Sean N. Finegan - Aberdeen NJ
James H. McFee - East Windsor NJ
Robert G. Swartz - Highlands NJ

Assignee:

AT&T Bell Laboratories - Murray Hill NJ

International Classification:

H05B 100
H01L 2120

US Classification:

219405

Abstract:

A substrate heating arrangement suitable for use in ultra-high vacuum MBE includes a filament responsive to a DC current for generating thermal energy, a metallic enclosure surrounding the filament and having an aperture at one end thereof, an intermediate semiconductor substrate parallel to and separated from a semiconductor growth substrate, and a substrate support mounted to the enclosure capable of holding the substrates in the prescribed relationship. The intermediate semiconductor substrate regulates the temperature on the surface of the semiconductor growth substrate to be less than or equal to a fixed temperature (approximately 1100. degree. C. for silicon) regardless of the DC current applied to the filament.