Mark J Rodwell

US Patent:

6522673, Feb 18, 2003

Filed:

Apr 20, 2000

Appl. No.:

09/553591

Inventors:

Robert A. Marsland - Madison WI
Mark Rodwell - Goleta CA

Assignee:

New Focus, Inc. - San Jose CA

International Classification:

H01S 310

US Classification:

372 29021, 385 31, 385 49

Abstract:

Described embodiments provide a method and apparatus for transmission of optical communications. An embodiment provides an optical transmitter which includes a control circuit to enhance the stability of output power levels, a modulator circuit with precise impedance matching for high frequency performance, and an optical coupling mechanism that relaxes the alignment tolerances between the laser and the fiber and decreases the sensitivity of the gain medium to feedback from devices coupled to the fiber. These features allow the transmitter to deliver an optical output beam which can be modulated over a wide range of frequencies, duty cycles and amplitudes with very precise definition of the rising and falling edges of the waveform. In combination these features result in an optical transmitter that may be fabricated with relatively low cost and a reduced form factor when compared with prior art optical transmitters.

US Patent:

7446584, Nov 4, 2008

Filed:

Sep 25, 2002

Appl. No.:

10/256099

Inventors:

Ken Elliott - Thousand Oaks CA, US
Susan Morton - Newbury Park CA, US
Mark Rodwell - Goleta CA, US

Assignee:

HRL Laboratories, LLC - Malibu CA

International Classification:

H03H 11/26

US Classification:

327280, 327359

Abstract:

Disclosed is a time delay generator apparatus and method. The apparatus includes a time delay gate , a mixer (a Gilbert cell circuit), and a current digital to analog converter. The mixer , comprised of first and second transistor differential pairs and , receives an analog input signal without a delay as well as a delayed input signal produced by the time gate delay. The digital to analog converter regulates the relative current flow between a first control signal and a second control signal , effectively altering the mixing of the undelayed input signal and the delayed input signal to generate a delayed output signal with a time or phase delay substantially equal to the temporal delay represented by the digital signal input. The time delay generator exhibits reduced phase noise and a linear time delay response.

US Patent:

7667515, Feb 23, 2010

Filed:

May 31, 2008

Appl. No.:

12/156266

Inventors:

Ken Elliott - Thousand Oaks CA, US
Susan Morton - Newbury Park CA, US
Mark Rodwell - Goleta CA, US

Assignee:

HRL Laboratories, LLC - Malibu CA

International Classification:

H03H 11/26

US Classification:

327280, 327359

Abstract:

Disclosed is a time delay generator apparatus and method. The apparatus includes a time delay gate , a mixer (a Gilbert cell circuit), and a current digital to analog converter. The mixer , comprised of first and second transistor differential pairs and , receives an analog input signal without a delay as well as a delayed input signal produced by the time gate delay. The digital to analog converter regulates the relative current flow between a first control signal and a second control signal , effectively altering the mixing of the undelayed input signal and the delayed input signal to generate a delayed output signal with a time or phase delay substantially equal to the temporal delay represented by the digital signal input. The time delay generator exhibits reduced phase noise and a linear time delay response.

US Patent:

20030075713, Apr 24, 2003

Filed:

Oct 22, 2001

Appl. No.:

10/032779

Inventors:

Rajashekhar Pullela - Westlake Village CA, US
Mark Rodwell - Goleta CA, US

International Classification:

H01L029/06

US Classification:

257/020000

Abstract:

A heterojunction bipolar transistor is provided with a graded band gap layer between a base and subcollector region. The graded band gap layer minimizes the surface leakage current path between the base and subcollector.

US Patent:

20030138024, Jul 24, 2003

Filed:

Jan 15, 2003

Appl. No.:

10/342933

Inventors:

Robert Williamson - Madison WI, US
Robert Marsland - Madison WI, US
Mark Rodwell - Goleta CA, US

Assignee:

New Focus, Inc.

International Classification:

H01S003/08
H01S003/04
H01S005/00

US Classification:

372/108000, 372/036000, 372/043000

Abstract:

The present invention provides a method and apparatus for transmission of optical communications. The present invention provides an optical transmitter which includes a control circuit to enhance the stability of output power levels, a modulator circuit with precise impedance matching for high frequency performance, and an optical coupling mechanism that relaxes the alignment tolerances between the laser and the fiber and decreases the sensitivity of the gain medium to feedback from devices coupled to the fiber. These features allow the transmitter to deliver an optical output beam which can be modulated over a wide range of frequencies, duty cycles and amplitudes with very precise definition of the rising and falling edges of the waveform. In combination these features result in an optical transmitter that may be fabricated with relatively low cost and a reduced form factor when compared with prior art optical transmitters. In an embodiment of the invention a semiconductor laser transmitter is disclosed. The semiconductor laser transmitter includes: a gain medium, an optical fiber, and a reflector. The gain medium generates an emission along a path. The optical fiber includes a tip portion located in the path to optically couple with the emission. A reflector is located on the tip portion to limit an optical coupling efficiency of said gain medium with said optical fiber. In an alternate embodiment of the invention a method for transmitting optical power is disclosed.

US Patent:

20090289714, Nov 26, 2009

Filed:

Oct 8, 2008

Appl. No.:

12/247974

Inventors:

Zachary M. Griffith - Thousand Oaks CA, US
Miguel E. Urteaga - Moorpark CA, US
Mark J.W. Rodwell - Santa Barbara CA, US

International Classification:

H03F 3/45

US Classification:

330260

Abstract:

The present invention relates generally to an operational amplifier. In one embodiment, the present invention is an operational amplifier including a transimpedance input stage, the transimpedance input stage including a first stage connected to a first resistor and a second resistor, and an output stage connected to the transimpedance input stage.

US Patent:

20110169568, Jul 14, 2011

Filed:

Feb 3, 2011

Appl. No.:

13/020689

Inventors:

Zachary M. Griffith - Thousand Oaks CA, US
Miguel E. Urteaga - Moorpark CA, US
Mark J.W. Rodwell - Santa Barbara CA, US

International Classification:

H03F 3/45
H03F 1/34
H01L 21/00

US Classification:

330260, 330291, 29 2501

Abstract:

The present invention relates generally to an operational amplifier. In one embodiment, the present invention is an operational amplifier including a transimpedance input stage, the transimpedance input stage including a first stage connected to a first resistor and a second resistor, and an output stage connected to the transimpedance input stage.

US Patent:

20120293263, Nov 22, 2012

Filed:

May 25, 2012

Appl. No.:

13/481312

Inventors:

Zachary M. Griffith - Thousand Oaks CA, US
Miguel E. Urteaga - Moorpark CA, US
Mark J.W. Rodwell - Santa Barbara CA, US

International Classification:

H03F 1/34
H03F 3/45

US Classification:

330260

Abstract:

An operational amplifier may include a transimpedance input stage. The operational amplifier is capable of self-biasing its input voltage(s) including a first stage, an input source connected to the first stage, an output stage connected to the first stage via feedback resistors, and feedback current sources connected to the first stage, wherein the feedback current sources are set to generate feedback currents flowing from the output stage back to the input stage via the feedback resistors, so as to self-bias the input voltage(s) at the input stage. A method for allowing for an op-amp to self-bias its input voltage(s), including generating feedback currents flowing from the output stage back to the input stage via feedback resistors, so as to self-bias the input voltage(s) at the input stage.