Scott R Justice

US Patent:

6366162, Apr 2, 2002

Filed:

Jan 2, 2001

Appl. No.:

09/753145

Inventors:

Chris W. Angell - Raleigh NC
Erik L. Bengtsson - Cary NC
Scott R. Justice - Durham NC
Aristotele Hadjichristos - Apex NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

G06G 726

US Classification:

327563

Abstract:

An input buffer circuit is operable to selectively present either low or high input impedance while maintaining uniform output impedance. The buffer is characterized by first and second amplifier circuits connected in parallel between an input to and an output from the buffer. The amplifiers are individually controlled between enabled and disabled states. When enabled, the first amplifier has low input impedance and predetermined output impedance and the second amplifier has high input impedance and the predetermined output impedance, and when disabled each amplifier has high input and output impedance. To operate the buffer to have low input impedance, the first amplifier is enabled while the second amplifier is disabled. To operate the buffer to have high input impedance, the second amplifier is enabled while the first amplifier is disabled. When an amplifier is disabled, its input and output impedances are sufficiently large that the disabled amplifier does not interfere with operation of the enabled amplifier.

US Patent:

6424229, Jul 23, 2002

Filed:

Jun 4, 2001

Appl. No.:

09/874408

Inventors:

Scott R. Justice - Durham NC
Erik L. Bengtsson - Lund, SE

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H03L 700

US Classification:

331 4, 331 10

Abstract:

Voltage controlled oscillator circuits are provided including a voltage controlled oscillator (VCO) having an input and an output responsive to the input. A tuning circuit coupled to the VCO sets a relationship between the input and the output of the VCO. An aided acquisition circuit is coupled to the input of the VCO. A control circuit selects a state of the tuning circuit to set the relationship between the input and the output of the VCO. The control circuit also controls operation of the aided acquisition circuit responsive to changes in the state of the tuning circuit. Methods for operating voltage controlled oscillator circuits are also provided. In addition, phase lock loop circuits and mobile terminals including the voltage controlled oscillator circuits are provided.

US Patent:

6496075, Dec 17, 2002

Filed:

Mar 14, 2001

Appl. No.:

09/808264

Inventors:

Scott Justice - Durham NC
Erik Bengtsson - Cary NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H03L 700

US Classification:

331 11, 331 1 A

Abstract:

A voltage controlled oscillator (VCO) is tunable over a wide frequency range while exhibiting low phase noise by dynamically switching between two or more voltage/frequency operating curves. Reference voltages establish switching thresholds for each operating curve. A control circuit compares the VCO tuning voltage to the reference threshold voltages, and based on that comparison and its previous outputs, generates switching signals effective to selectively couple and decouple one or more frequency altering devices to the VCO.

US Patent:

6545555, Apr 8, 2003

Filed:

Oct 12, 2000

Appl. No.:

09/689570

Inventors:

Scott Justice - Durham NC
Erik Bengtsson - Cary NC

Assignee:

Telefonaktiebolaget, LM Ericsson - Stockholm

International Classification:

H03B 500

US Classification:

331117R, 331 36 C, 331113 R, 331177 V, 331175

Abstract:

Differential voltage controlled oscillators are provided including a differential oscillator core, a first linear capacitor, a second linear capacitor, a first phase noise reduction device, and a second phase noise reduction device. The differential oscillator core has a first output that is capacitively coupled to a first differential input thereof by a first semiconductor junction having a first non-linear capacitance, and a second output that is capacitively coupled to a second differential input thereof by a second semiconductor junction having a second non-linear capacitance. The first linear capacitor is electrically cross-coupled from the first differential input to the second output, while the second linear capacitor electrically cross-coupled from the second differential input to the first output. The first phase noise reduction device has a first non-linear capacitance characteristic, and is electrically cross-coupled from the first differential input to the second output. The second phase noise reduction device has a second non-linear capacitance characteristic, and is electrically cross-coupled from the second differential input to the first output.

US Patent:

6909757, Jun 21, 2005

Filed:

May 14, 2001

Appl. No.:

09/854649

Inventors:

Scott R. Justice - Durham NC, US
Erik L. Bengtsson - Lund, SE
David R. Pehlke - Chapel Hill NC, US

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H04L027/36

US Classification:

375297, 375298, 455110, 4551271, 455522

Abstract:

Embodiments of methods, transmitters, and computer program products are provided for transmitting a signal by adjusting a delay between an amplitude component of the signal and a phase component of the signal based on the transmission power. Error vector magnitude and adjacent channel power ratio are two common criteria used in evaluating transmitter performance. By adjusting the delay between the amplitude component of the transmitted signal and the phase component of the transmitted signal, the error vector magnitude and/or the adjacent channel power ratio may be reduced. The particular delay value that provides the best error vector magnitude performance and/or adjacent channel power ratio performance may differ based on the transmission power level. Therefore, the delay value is adjusted based on the transmission power.

US Patent:

6975686, Dec 13, 2005

Filed:

Oct 31, 2000

Appl. No.:

09/703037

Inventors:

M. Ali Khatibzadeh - Morrisville NC, US
Aristotle Hadjichristos - Apex NC, US
Scott R. Justice - Durham NC, US
Steven G. Cairns - Louisburg NC, US
Charles Gore, Jr. - McKinney TX, US
Jeffrey Schlang - Dallas TX, US
Erik Bengtsson - Cary NC, US
David R. Pehlke - Chapel Hill NC, US

Assignee:

Telefonaktiebolaget L.M. Ericsson

International Classification:

H04L027/04
H04L027/12
H04L027/20

US Classification:

375295, 455 91

Abstract:

A digital signal processor generates in-phase, quadrature-phase and amplitude signals from a baseband signal. A modulator modulates the in-phase and quadrature-phase signals to produce a modulated signal. A phase locked loop is responsive to the modulated signal. The phase locked loop includes a controlled oscillator having a controlled oscillator input. An amplifier includes a signal input, amplitude control input and an output. The signal input is responsive to the controlled oscillator output and the amplitude control input is responsive to the amplitude signal. The in-phase and quadrature-phase signals may be normalized in-phase and quadrature-phase signals. Alternatively, a phase tracking subsystem may be provided that is responsive to the quadrature modulator to produce a phase signal that is responsive to phase changes in the modulated signal and that is independent of amplitude changes in the modulated signal. An amplitude tracking subsystem also may be provided that is responsive to the modulator to produce an amplitude system that is responsive to amplitude changes in the modulated signal and that is independent of the phase changes in the modulated signal. An amplifier has a signal output, an amplitude control input and an output.

US Patent:

7072421, Jul 4, 2006

Filed:

Dec 22, 2000

Appl. No.:

09/746823

Inventors:

Erik Bengtsson - Cary NC, US
Aristotle Hadjichristos - Apex NC, US
Scott R. Justice - Durham NC, US

Assignee:

Telefonaktiebolaget L.M. Ericsson - Stockholm

International Classification:

H04L 27/36

US Classification:

375298, 332127

Abstract:

A digital signal processor generates in-phase, quadrature-phase and amplitude signals from a baseband signal. A modulator modulates the in-phase and quadrature-phase signals to produce a modulated signal. A phase locked loop is responsive to the modulated signal. The phase locked loop includes a controlled oscillator having a controlled oscillator input. An amplifier includes a signal input, amplitude control input and an output. The signal input is responsive to the controlled oscillator output and the amplitude control input is responsive to the amplitude signal. The phase locked loop that is responsive to the modulated signal includes a controlled oscillator output and a feedback loop between the controlled oscillator input and the controlled oscillator output. The feedback loop includes a mixer that is responsive to a local oscillator. The modulator may be placed in the phase locked loop.

US Patent:

58382070, Nov 17, 1998

Filed:

Dec 20, 1996

Appl. No.:

8/770889

Inventors:

Xue-Song Zhou - Chapel Hill NC
Scott Richard Justice - Durham NC

Assignee:

Ericsson Inc. - Research Triangle Park NC

International Classification:

H03B 512

US Classification:

331 36C

Abstract:

A voltage controlled oscillator has an active circuit, a resonant circuit coupled to the input node of the active circuit and an adjustable impedance circuit coupled to an output node of the active circuit. The impedance of the adjustable impedance circuit may be altered to tune the oscillation frequency of the oscillator. In one embodiment, the adjustable impedance circuit includes a varactor diode in series with a capacitor and means for varying the voltage across the varactor diode. An isolation circuit is coupled to an output node of the active circuit. In one embodiment, the isolation circuit is connected to a different output node than the adjustable impedance circuit is connected to.