Abstract: A power amplifier circuit includes a main amplifier circuit having a main amplifier for amplifying an input signal in one of a full-power mode and at least a back-off mode. A first peak amplifier circuit is in parallel with the main amplifier circuit. The first peak amplifier circuit has a peak amplifier in series with a transmission line. The peak amplifier is configured to be activated in the full-power mode and to be de-activated in at least the back-off mode. A combining node is connected to an output of the main amplifier circuit and an output of the transmission line. In some embodiments, a matching network is connected at the output of the combining node. In some embodiments, the transmission line is selected so the first peak amplifier circuit appears substantially as an open circuit to the combining node.

Abstract: A multi-band transmitter circuit may include a multi-port network configured to divide an input multi-band signal comprising signal components at each of a plurality of frequency bands into a plurality of output multi-band signals. The multi-band transmitter circuit may also include a plurality of band-specific circulator paths. Each band-specific circulator path includes a circulator configured to receive the respective output multi-band signal and operate at a respective one of the frequency bands to provide a respective band-specific signal. The multi-band transmitter circuit further includes a filter circuit that includes a plurality of band-specific filter elements. Each band-specific filter element is coupled to a corresponding circulator and configured to receive the respective band-specific signal and operate at the same frequency band as the corresponding circulator to provide a filtered band-specific signal for transmission.

Abstract: A multi-band transmitter circuit may include a multi-port network configured to divide an input multi-band signal comprising signal components at each of a plurality of frequency bands into a plurality of output multi-band signals. The multi-band transmitter circuit may also include a plurality of band-specific circulator paths. Each band-specific circulator path includes a circulator configured to receive the respective output multi-band signal and operate at a respective one of the frequency bands to provide a respective band-specific signal. The multi-band transmitter circuit further includes a filter circuit that includes a plurality of band-specific filter elements. Each band-specific filter element is coupled to a corresponding circulator and configured to receive the respective band-specific signal and operate at the same frequency band as the corresponding circulator to provide a filtered band-specific signal for transmission.

Abstract: A power amplifier circuit includes a main amplifier circuit having a main amplifier for amplifying an input signal in one of a full-power mode and at least a back-off mode. A first peak amplifier circuit is in parallel with the main amplifier circuit. The first peak amplifier circuit has a peak amplifier in series with a transmission line. The peak amplifier is configured to be activated in the full-power mode and to be de-activated in at least the back-off mode. A combining node is connected to an output of the main amplifier circuit and an output of the transmission line. In some embodiments, a matching network is connected at the output of the combining node. In some embodiments, the transmission line is selected so the first peak amplifier circuit appears substantially as an open circuit to the combining node.

Abstract: The output of a carrier amplifier circuit in a Doherty amplifier is coupled to the summing node so that the impedance observed by the carrier amplifier's output is approximately equal to the load impedance at the combining node when the load impedance is not modulated. In an example non-inverting configuration, a power amplifier circuit is configured to provide an amplified signal to a load at a summing node, where the load has a first impedance when not load-modulated. The power amplifier circuit includes a splitter network arranged to receive the input signal and to split the input signal to provide a carrier input signal and a peaking input signal, a carrier amplifier path configured to amplify the carrier input signal in a full-power mode and in a first backoff mode, and a peaking amplifier path configured to amplify the peaking input signal in at least the full-power mode.

Abstract: The output of a carrier amplifier circuit in a Doherty amplifier is coupled to the summing node so that the impedance observed by the carrier amplifier's output is approximately equal to the load impedance at the combining node when the load impedance is not modulated. In an example non-inverting configuration, a power amplifier circuit is configured to provide an amplified signal to a load at a summing node, where the load has a first impedance when not load-modulated. The power amplifier circuit includes a splitter network arranged to receive the input signal and to split the input signal to provide a carrier input signal and a peaking input signal, a carrier amplifier path configured to amplify the carrier input signal in a full-power mode and in a first backoff mode, and a peaking amplifier path configured to amplify the peaking input signal in at least the full-power mode.

Abstract: A method and system for design and implementation of symmetric and asymmetric Doherty power amplifiers are disclosed. Quarter wave transmission lines are interposed between the main and peak power amplifiers of a Doherty power amplifier system and a 3 dB hybrid coupler. The impedances of the quarter wavelength transmission lines are chosen based on a ratio of the power ratings of the main and peak power amplifiers such that the impedances seen by the main and peak power amplifiers is independent of the impedance of the 3 dB coupler.