Motorola Corporation

James John Crnkovic

David S Peckham

Jin D Kim

Armin Werner Klomsdorf

A unique method and apparatus modifies the load impedance at the output of a power amplifier by varying a voltage variable capacitor (VVC) (310) to maximize the efficiency of the power amplifier (304). A comparator (509) generates amplifier control signal (211) based upon a detected power output signal (216) and a reference signal. In addition to providing power control, the control signal is also coupled to a VVC circuit (506) to control the output impedance of the power amplifier. In an alternate embodiment, a separate VVC control signal (527) based upon a comparison of the power control signal and the battery voltage is coupled to a VVC. In another alternate embodiment, a second VVC can be coupled in parallel to the first VVC. The second VVC is preferably controlled by a signal (805) based upon the current in the power amplifier. Finally, an alternate embodiment incorporates a VVC circuit (506) at the input of the power amplifier to compensate for variations in input impedance to improve other power amplifier parameters such as IM, gain, output power and noise level.

Method and apparatus for amplifying a signal

A portable radio transceiver (100) includes a transmitter (101) and a receiver (103) operating at different respective frequencies. The transmitter (101) is capable of producing an undesired signal (121) including a frequency substantially equal to the receiver operating frequency (107). A first antenna (102) is coupled to the transmitter (101). A second antenna (104) is coupled to the receiver (103) and electrically isolated (122) from the first antenna (102) by a predetermined degree such that the undesired signal (121) received by the second antenna (104) is attenuated by the predetermined degree of electrical isolation (122). An optional filter (112), coupled to an input terminal of an amplifier (113) in the transmitter (101), is adapted to attenuate the undesired signal (121) such that the undesired signal (121) received by the second antenna (104) is further attenuated. An optional directional attenuator (115), coupled between the amplifier (113) and the first antenna (102), is adapted to attenuate an interfering signal (123) received by the first antenna (102) such that the undesired signal (121) received by the second antenna (104) is further attenuated.

Apparatus and method for attenuating an undesired signal in a radio

A three way oscillator signal power splitting circuit splits power provided at the output of a voltage controlled oscillator (VCO). The circuit is implemented on a printed circuit board section having a first layer which includes a first conductor for receiving the power from the VCO, a second layer having a second conductor, substantially parallel to and adjacent the first conductor, for receiving a portion of the power on the first main conductor via broadside coupling, and a third conductor, situated substantially parallel to and adjacent the first and second conductors, for receiving a portion of the power on the first main conductor also via broadside coupling. A ground conductor is additionally included on the third layer for providing a ground reference for the first, second and third conductors, and resistors are used to terminate the second and third conductors.

Growing community of inventors

Lake Zurich, IL, United States of America

James John Crnkovic