Abstract: The present invention relates to a power amplifier. The present invention particularly relates to switched-mode power amplifiers operable in a frequency range between 0.5 GHz and 40 GHz, and configured for outputting powers ranging from 1 W to 1 kW. The present invention further relates to an impedance matching stage to be used in such power amplifier. The impedance matching stage of the present invention comprises a short-circuited stub at its input, an open-circuited stub at its output, and a series branch connecting the input and output. By choosing suitable characteristic impedances and electrical lengths of the stubs and the series branch it becomes possible to independently choose the impedance to be presented to the power transistor at the fundamental and second harmonic frequencies.

Abstract: The present invention relates to a four-way Doherty amplifier. The invention further relates to a mobile telecommunications base station. The invention proposes a new Doherty combiner topology that allows peak efficiencies to be reached at deeper back-off levels than conventional Doherty combiners.

Abstract: The present invention relates to a four-way Doherty amplifier. The invention further relates to a mobile telecommunications base station. The invention proposes a new Doherty combiner topology that allows peak efficiencies to be reached at deeper back-off levels than conventional Doherty combiners.

Abstract: A power amplifier (20) for operation in at least a first and a second frequency band, wherein a center frequency f2 of the second frequency band is higher than a center frequency f1 of the first frequency band, is disclosed. The power amplifier (20) comprises a transistor (35) for amplifying an input signal of the power amplifier (20) and an output coupling network (45) for connecting the power amplifier to a resistive load (55). The output coupling network (45) is operatively connected to an output terminal (40) of the transistor (35), has an output terminal (50) for connection to said resistive load (55), and is configured such that, when the power amplifier (20) is connected to said resistive load (55), the power amplifier (20) is arranged to operate in class F for frequencies in one of the first and the second frequency bands, and operate in inverse class F for frequencies in the other one of the first and the second frequency band.

Abstract: A power amplifier (20) for operation in at least a first and a second frequency band, wherein a center frequency f2 of the second frequency band is higher than a center frequency f1 of the first frequency band, is disclosed. The power amplifier (20) comprises a transistor (35) for amplifying an input signal of the power amplifier (20) and an output coupling network (45) for connecting the power amplifier to a resistive load (55). The output coupling network (45) is operatively connected to an output terminal (40) of the transistor (35), has an output terminal (50) for connection to said resistive load (55), and is configured such that, when the power amplifier (20) is connected to said resistive load (55), the power amplifier (20) is arranged to operate in class F for frequencies in one of the first and the second frequency bands, and operate in inverse class F for frequencies in the other one of the first and the second frequency band.