Ericsson Gmbh

Teresa Anne Muhlbauer

Thomas Joseph Karpus

Michael E Nowak

Ronald Oliver

Difference frequency impedance transformation circuits for power amplifiers can change the impedance presented to an input of a power amplifier at a frequency that is a function of a difference between the receive and transmit frequency ranges. The difference frequency impedance transformation circuit may, therefore, reduce the noise at the difference frequency which may otherwise be mixed with the transmit frequencies to produce noise in the receive frequency range. In particular, difference frequency impedance transformation circuits can include a first circuit that conducts the first signals to an input of the power amplifier. A second circuit is electrically coupled to the input of the power amplifier and changes the impedance presented to the input of the power amplifier at the difference frequency. Related power amplifier systems, wireless user terminals, and methods are also disclosed.

Difference frequency impedance transformation circuits and methods for providing same in power amplifier systems

A method is provided for controlling the quiescent current of a power amplifier in a wireless communication device, the amplifier configured to amplify an applied communication signal and employing biasing controlled by a reference voltage. In a preferred embodiment, the method includes: measuring the operating current of the communication device with no communication signal applied to the amplifier and with the reference voltage set to zero, increasing the reference voltage, while continuing to measure the operating current, until the difference between the operating current at a particular reference voltage and the operating current with the reference voltage set to zero reaches a pre-selected current value, and storing a digital value corresponding to the particular reference voltage. The pre-selected current value is preferably determined by characterizing a sufficient sample of amplifiers (e.g., based on model or production lot) to determine a minimum amplifier quiescent current adequate to meet desired performance characteristics for a particular system or application.

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Cary, NC, United States of America

Teresa Anne Muhlbauer