David A Rich

US Patent:

6404364, Jun 11, 2002

Filed:

Aug 24, 2000

Appl. No.:

09/645003

Inventors:

H. Scott Fetterman - New Tripoli PA
David Arthur Rich - Whitehall PA

Assignee:

Agere Systems Guardian Corp. - Orlando FL

International Classification:

H03M 120

US Classification:

341131, 341161, 341155, 341141, 341143

Abstract:

A multistage converter and method for converting a sampled analog signal to a corresponding digital representation. Each stage of the converter receives an analog input signal and produces a partial digital output. A first stage receives the sampled analog signal as the analog input signal. Each stage provides a residue output, which is the analog input signal to a subsequent stage. The residue is the analog input signal to the stage, less the analog equivalent of the partial digital output from the stage, possibly with a gain change. A voltage range over which a sample of an analog signal can vary is defined by a lower limit and an upper limit. A lower comparator threshold is established within the voltage range. An upper comparator threshold is established within the voltage range, between the lower comparator threshold and the upper limit. The analog input to the stage is quantized based on the lower and upper comparator thresholds to generate a quantized sampled analog signal.

US Patent:

7498876, Mar 3, 2009

Filed:

Jun 15, 2006

Appl. No.:

11/453398

Inventors:

Robert O. Peruzzi - Bethlehem PA, US
David A. Rich - Monroe Township NJ, US

Assignee:

Agere Systems Inc. - Allentown PA

International Classification:

H03F 3/38
H03G 3/20

US Classification:

330 10, 330136

Abstract:

An amplifier adapted to generate an analog output signal in response to a digital input signal and having an output stage powered by a power-supply circuit, which generates one or more power rails for the output stage such that at least one of these power rails tracks the output signal and substantially represents a biased and half-wave rectified version of that output signal.

US Patent:

56465181, Jul 8, 1997

Filed:

Nov 18, 1994

Appl. No.:

8/342188

Inventors:

Kadaba R. Lakshmikumar - Wescosville PA
Krishnaswamy Nagaraj - Somerville NJ
David Arthur Rich - Woodmere NY
Khong-Meng Tham - Reading PA

Assignee:

Lucent Technologies Inc. - Murray Hill NJ

International Classification:

G05F 316

US Classification:

323316

Abstract:

Briefly, in accordance with one embodiment of the invention, a current source comprises: a first and a second current path, the current paths being coupled so as to provide, during circuit operation, first and second currents through the respective current paths in a substantially predetermined direct proportion. The current source further includes an operational amplifier having its respective input terminals coupled to the first and second current paths, the operational amplifier being coupled in a feedback configuration so as to maintain substantially equal voltages between a first and second predetermined point respectively located along the first and second current paths. Furthermore, the respective first and second currents are related to the respective first and second voltages substantially in accordance with the junction diode equation.

US Patent:

57450617, Apr 28, 1998

Filed:

Jul 28, 1995

Appl. No.:

8/508944

Inventors:

Steven Robert Norsworthy - Emmaus PA
David Arthur Rich - Whitehall PA

Assignee:

Lucent Technologies Inc. - Murray Hill NJ

International Classification:

H03M 118

US Classification:

341131

Abstract:

Briefly, in accordance with one embodiment of the invention, a circuit comprises: a sigma-delta modulator including an input signal port, an output signal port, and a signal path. The signal path includes a feedforward signal path and a feedback signal path. The signal path is adapted to be coupled to a dither signal and the circuit is adapted to adjust the dither signal substantially in accordance with a signal applied to the input signal port. In accordance with another embodiment of the invention, a method of improving the stability of a sigma-delta modulator, the modulator employing dither, comprises the steps of: applying a signal to the input port of the sigma-delta modulator; applying a dither signal to the signal path of the sigma-delta modulator; and adjusting the dither signal applied substantially in accordance with the signal applied to the input port.

US Patent:

55304427, Jun 25, 1996

Filed:

May 9, 1994

Appl. No.:

8/239644

Inventors:

Steven R. Norsworthy - Emmaus PA
David A. Rich - Woodmere NY
Robert W. Walden - Bethlehem PA

Assignee:

AT&T Corp. - Murray Hill NJ

International Classification:

H03M 120

US Classification:

341131

Abstract:

A device comprises: an analog-to-digital converter; a digital signal processor; a digital dither signal generator; and a signal coupling device adapted to selectively couple one of the dither signal generator and the digital signal processor to the signal path in the converter. A method of testing a dithered analog-to-digital converter employing an M-bit digital signal generator, M being a positive integer, comprises the steps of: generating an M-bit, periodic signal; providing the generated signal to the dithered converter at a point along the signal path of the dithered converter in place of the dither signal; and measuring the digital output signal produced by the converter.

US Patent:

56753527, Oct 7, 1997

Filed:

Sep 7, 1995

Appl. No.:

8/526026

Inventors:

David Arthur Rich - Whitehall PA
Harold Joseph Wilson - Green Lane PA

Assignee:

Lucent Technologies Inc. - Murray Hill NJ

International Classification:

G09G 300

US Classification:

345 89

Abstract:

In accordance with one aspect of the invention, a liquid crystal display driver for driving liquid crystal display electrodes, comprises: a voltage signal generator adapted to provide a predetermined voltage signal to the liquid crystal display electrodes, the voltage signal generator being further adapted to be activated when the voltage signal level of said electrodes is outside a predetermined dead zone region, the voltage signal generator being deactivated when the voltage signal level of the electrodes is substantially within the predetermined dead zone region; and a switch adapted to couple the voltage signal generator to at least one of said liquid crystal display electrodes. In accordance with another aspect of the invention, a method for providing voltage signals to electrodes of a liquid crystal display, comprising the steps of activating a first voltage signal generator to provide a voltage signal for the electrodes when the voltage signal level of the ectrodes falls outside a dead zone region; and deactivating the first voltage signal generator when the voltage signal level of the electrodes falls within the dead zone region.

US Patent:

58475567, Dec 8, 1998

Filed:

Dec 18, 1997

Appl. No.:

8/994019

Inventors:

Makeshwar Kothandaraman - Emmaus PA
Bijit Thakorbhai Patel - Breinigsville PA
David Arthur Rich - Whitehall PA

Assignee:

Lucent Technologies Inc. - Murray Hill NJ

International Classification:

G05F 316

US Classification:

323315

Abstract:

A current source includes a first current mirror and a second current mirror that share a common current path. The current in the common current path mirrors a current of a current reference connected to the first current mirror. A current in an output current path of the second current mirror mirrors the current of the common current path. A first feedback loop controls the current in the common current path and a second feedback loop matches a voltage of the common current path with an output voltage. The cooperation of the first and second feedback loops ensures that the output current replicates the current of the current reference even when an voltage of the current source is close to the supply voltage. Thus, the voltage swing of the current source output voltage is increased and a precision current source is provided even when the output voltage is close to the supply voltage.

US Patent:

59399040, Aug 17, 1999

Filed:

Feb 19, 1998

Appl. No.:

9/026211

Inventors:

H. Scott Fetterman - New Tripoli PA
David A. Rich - Whitehall PA

Assignee:

Lucent Technologies, Inc. - Murray Hill NJ

International Classification:

H03K 522

US Classification:

327 67

Abstract:

A method and device for controlling the common-node output voltage of a differential buffer is disclosed. According to the invention, the common-mode output voltage of the differential buffer is controlled to a desired value by supplying a first current to the output of the differential buffer and supplying a second current to the output of the differential buffer, the second current being opposite in polarity and lower in magnitude than the first current. The common-mode output voltage of the differential buffer is sensed and an adjustment current is added to the second current to adjust the common-mode output voltage to the desired value.