David M Lovelace

US Patent:

20060217087, Sep 28, 2006

Filed:

Apr 28, 2006

Appl. No.:

11/413999

Inventors:

William Snelgrove - Toronto, CA
David Lovelace - Austin TX, US
Richard Wilson - Austin TX, US
Kelly Mekechuk - Austin TX, US
Thomas Blease - Hollister CA, US

International Classification:

H01Q 11/12
H04B 1/04

US Classification:

455126000

Abstract:

A radio frequency power amplifier and corresponding method is arranged and configured to drive a resonant load. The radio frequency power amplifier includes a radio frequency switching stage with an output that is coupled to a resonant circuit. The switching stage is configured to provide an output signal with amplitude modulation corresponding to amplitude modulation of an input signal when powered from a fixed voltage power supply. The amplifier further includes a feedback control system coupled to the input signal and the output signal, where the feedback control system includes a sequencer configured to provide a sequencer output that is used to drive the radio frequency switching stage. The amplifier also includes an amplitude control system coupled to the output of the radio frequency switching stage and configured to limit an amplitude of the output signal and in some embodiments a power recovery system.

US Patent:

59260521, Jul 20, 1999

Filed:

Aug 8, 1997

Appl. No.:

8/908827

Inventors:

Stephen W. Dow - Austin TX
Jeffrey C. Durec - Chandler AZ
David K. Lovelace - Chandler AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H03H 1116
H03K 300

US Classification:

327234

Abstract:

A circuit and method for producing a phase shifted quadrature signal (VOUT) from an in-phase signal (VIN). The in-phase signal (VIN) is applied to the control electrode of a voltage follower (121). The voltage follower (121) has a variable output resistance which combines with a capacitor (123) to delay the input signal (VIN) in accordance with the time constant formed by the variable output resistance and the capacitor (123). The variable output resistance is controlled by adjusting the bias current of the voltage follower (121) with a control signal.