Resources Contact Us Home
Method and apparatus for amplifying a signal

Image Number 8 for United States Patent #6020787.

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.

  Recently Added Patents
ZnO green luminescent material and its preparation
Toner cartridge and image forming apparatus including the same
Multi-carrier operation for wireless systems
Anthranilic diamide compositions for propagle coating
MOS resistor apparatus and methods
Blueberry plant named `DrisBlueFour`
Liquid crystal display
  Randomly Featured Patents
Electromagnetic radiation reflector
Rotatable cutting tool-tool holder assembly
Waterproof electrical connector
N.sup.2 -Naphthalenesulfonyl-L-arginine derivatives and the pharmaceutically acceptable acid addition salts thereof
Decorative candleholder
Hybrid electrophotographic apparatus for custom color printing
Dual port static RAM with bidirectional shift capability
Identification and isolation of multipotential neural progenitor cells from the subcortical white matter of the adult human brain
Combustion system
Photo-remediation of NO2 plume