Image Number 4 for United States Patent #7446612.
A wireless communication device output amplifier configured to reduce or eliminate out of band oscillations from voltage standing waves generated by antenna impedance mismatch reflection. The amplifier is configured with an input, output, and biasing node. The biasing node is configured to receive a biasing signal from a biasing amplifier. The biasing amplifier draws current from the biasing node while providing the biasing voltage to the output amplifier. To reduce or eliminate out of band voltage standing waves from antenna reflections, a frequency dependant network is provided as a feedback loop to selectively provide feedback to the output amplifier to reduce or eliminate unwanted out of band oscillations, such as voltage standing waves. The frequency dependant network may comprise one or more resistors, inductors, and capacitors which are of small size and may be integrated.