A power amplifier circuit includes a power splitter, a first amplifier configured to output a first amplified signal from a first output terminal, and a second amplifier configured to output a second amplified signal from a second output terminal. The power amplifier circuit further includes a first termination circuit connected between the first output terminal and the second output terminal, a first transmission line, a second transmission line, a second termination circuit connected between another end of the first transmission line and another end of the second transmission line, and a power combiner.

Radio frequency (RF) amplification devices are disclosed that include Doherty amplification circuits and methods of operating the same. In one embodiment, a Doherty amplification circuit includes a main carrier RF amplifier, a peaking RF amplifier, and a periodic quadrature coupler. To provide Doherty amplification, the peaking RF amplifier is configured to be deactivated while an RF signal is below a threshold level and is configured to be activated while the RF signal is above the threshold level. The periodic quadrature coupler is configured to combine a first RF split signal from the main carrier RF amplifier and a second RF split signal from the peaking RF amplifier into the RF signal, such that the RF signal is output from an output port while the peaking RF amplifier is activated. The periodic quadrature coupler allows the Doherty amplification circuit to provide broadband amplification in various RF communication bands.

A driver circuit for a composite power amplifier configured to operate in at least one Chireix-mode a first and a second sub-amplifier for amplification of an input signal into an output signal is disclosed. An input network of the driver circuit comprises a means configured to provide a first signal which is linearly derivable from the input signal, and a second signal which is non-linearly derivable from the input signal. The input network combines the first signal, at zero degrees phase shift, and the second signal, at 90 degrees phase shift, to obtain a first feeding signal for the first sub-amplifier. Furthermore, the input network combines the first signal, at 180 degrees phase shift, and the second signal, at 90 degrees phase shift, to obtain a second feeding signal for the second sub-amplifier.

An in-line waveguide divider divides power of an incoming high-frequency signal among openings. Amplification boards disposed on a base are provided for respective openings and are each connected in parallel with one another to the in-line waveguide divider. An in-line waveguide combiner includes openings formed correspondingly to the amplification boards, and is connected to the amplification boards. An electrically conductive amplifier cover includes walls formed to provide isolation between circuits of the amplification boards continuously from the in-line waveguide divider to the in-line waveguide combiner, and the entire surface of the amplification boards at the in-line waveguide combiner side is covered with the electrically conductive amplifier cover except openings and openings. Each of the amplification boards includes a waveguide-to-microstrip transition corresponding to the opening, an amplifier element, and a microstrip-to-waveguide transition corresponding to the opening.

A multistage linear power amplifier receiving an input signal. The multistage linear power amplifier comprises a plurality of Class-AB amplifiers connected in a cascade configuration. The plurality of Class-AB amplifiers amplifies the input signal to generate an amplified input signal. At least one of the plurality of Class-AB amplifiers is biased such that the multistage linear power amplifier emulates a Class-C amplifier.

An amplifier arrangement comprises N amplifier stages, wherein N is an integer equal or greater than five. The amplifier arrangement comprises a first cascade of quarter wavelength transmission line segments coupled to receive a first set of amplifier stages, and at least a second cascade of quarter wavelength transmission line segments coupled to receive a second set of amplifier stages. The first cascade and second cascade are connected to a common node, for example in parallel to an output node, or in parallel to an intermediate node.

A method of operating a headphone configured to be removed from and placed in close proximity to a user's ear can include generating an input signal by an input signal generating device. The method can also include determining whether an insertion event has occurred based on the generated input signal and causing the headphone to operate in 5 a low power mode responsive to an absence of an insertion event determination after a first period of time. The method can also include causing the headphone to operate in an ultra-low power mode responsive to the absence of an insertion event determination after a second period of time that occurs after the first period of time, the ultra-low power mode having a lower power consumption than the low power mode.

A multichannel transmission system which includes a calibration functionality that allows precise calibration of the frequency conversion chains and of the multiport amplifier of the system to be performed without interruption of service. The proposed calibration makes it possible to correct the defects over the entire frequency band of the system.

An on-chip transformer circuit is disclosed. The on-chip transformer circuit comprises a primary winding circuit comprising at least one turn of a primary conductive winding arranged as a first N-sided polygon in a first dielectric layer of a substrate; and a secondary winding circuit comprising at least one turn of a secondary conductive winding arranged as a second N-sided polygon in a second, different, dielectric layer of the substrate. In some embodiments, the primary winding circuit and the secondary winding circuit are arranged to overlap one another at predetermined locations along the primary conductive winding and the secondary conductive winding, wherein the predetermined locations comprise a number of locations less than all locations along the primary conductive winding and the secondary conductive winding.

A high-frequency power amplifier apparatus includes: a plurality of amplifiers that respectively amplify a plurality of distributed signals obtained by distributing a high-frequency signal of a predetermined frequency, the amplifiers respectively outputting a plurality of amplified signals; and a cavity-type high-frequency power combiner having a cavity surrounded by a conductor wall, the cavity-type high-frequency power combiner combining together power of the plurality of amplified signals in the cavity by operating in a TE.sub.011 resonance mode with a resonance frequency equal to the predetermined frequency.