Amplifiers – With semiconductor amplifying device – Including gain control means
Patent
1997-07-29
2000-02-01
Pascal, Robert
Amplifiers
With semiconductor amplifying device
Including gain control means
330284, 330145, 455126, H03G 310, H03F 130, H01Q 1112
Patent
active
060207876
ABSTRACT:
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.
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Crnkovic James John
Kim Jin Dong
Klomsdorf Armin Werner
Peckham David Sutherland
Collopy Daniel R.
King John J.
Motorola Inc.
Nguyen Patricia T.
Pascal Robert
LandOfFree
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