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
Inhibitors of bacterial nitric oxide synthase, and related screening methods
Film, polarizing plate and display device, and method of manufacturing film
Method and apparatus for filter-less class D audio amplifier EMI reduction
Method and system for prioritizing points of interest for display in a map using category score
Bipolar transistor with diffused layer between deep trench sidewall and collector diffused layer
Reduced sorbent utilization for circulating dry scrubbers
  Randomly Featured Patents
Daisy chain multiplexer
Method of providing location service for WLAN user
Color display system
Integral base plate/spin motor assembly with taped cover
Method and apparatus for controlling sheet shape in sheet rolling
Shoe upper
Injury protection device for machinery
Lighting system including LED with glass-coated quantum-dots
Pump-free water-cooling system
Multiple bits-per-cell flash EEPROM memory cells with wide program and erase V.sub.t window