Disclosed is a Doherty power amplifier. At least one power amplification tube and other power amplification tubes in the Doherty power amplifier are located in different planes.

An amplifier device for high frequency signals, in particular a linear high frequency amplifier device, which comprises at least one input, an incoming line, a pre-distortion unit, in particular an adaptive pre-distortion unit, an amplifier unit, in particular a non-linear power amplifier unit, a transmission line, a feedback unit, and an output. The output is connected to the amplifier unit via the transmission line. In addition, the at least one input is connected to the pre-distortion unit such that two incoming branch lines are provided which are interconnected by a switching unit. A first incoming branch line of the incoming branch lines comprises a down-converter being arranged between the at least one input and the pre-distortion unit.

A semiconductor device includes: a semiconductor substrate whose contour is a pentagon; a front-stage amplifier formed relatively near a vertex of the pentagon of the semiconductor substrate; and a rear-stage amplifier formed relatively near a side opposed to the vertex of the semiconductor substrate and amplifying an output from the front-stage amplifier.

A two-stage amplifier of a type of the current re-use configuration is disclosed. The amplifier includes first to third transistors, where the first transistor constitute the first stage, while, the latter two transistors constitute the second stance. The first to third transistors are connected in series between a power supply and ground such that a bias current supplied to the third transistor flows in the second and first transistors. The first transistor in the source thereof is grounded in the DC mode. The second transistor is grounded in the AC mode but floated in the DC mode. The third transistor that outputs an amplified signal is connected in parallel in the AC mode but in series in the DC mode with respect to the second transistor.

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 transmit circuit for sending and/or receiving at least one single-ended signal and for sending a differential signal on two transmission lines, including: a differential amplifier for sending signal parts of a differential signal via the two transmission lines, two impedance matching resistances that are situated between the transmission lines, connected in series, for the impedance matching of the differential amplifier; a switch that is connected in series between the impedance matching resistances; at least one single-ended transmit amplifier for sending or receiving a single-ended signal via an associated one of the transmission lines, each of the at least one single-ended transmit amplifiers being connected to a terminal of the switch that is connected, via the corresponding impedance matching resistance to the associated transmission line.

A transmit circuit for sending and/or receiving at least one single-ended signal and for sending a differential signal on two transmission lines, including: a differential amplifier for sending signal parts of a differential signal via the two transmission lines, two impedance matching resistances that are situated between the transmission lines, connected in series, for the impedance matching of the differential amplifier; a switch that is connected in series between the impedance matching resistances; at least one single-ended transmit amplifier for sending or receiving a single-ended signal via an associated one of the transmission lines, each of the at least one single-ended transmit amplifiers being connected to a terminal of the switch that is connected, via the corresponding impedance matching resistance to the associated transmission line.

An apparatus includes an input port, an output port, and a plurality of amplifier stages connected in parallel between the input port and the output port. Each of the amplifier stages comprises a common source field effect transistor (CSFET) and at least two common gate field effect transistors (CGFETs) coupled in series with a drain of the common source FET. At least one of the common gate field effect transistors of each stage includes a stabilizing network connected between drain and source diffusions.

An apparatus includes an input port, an output port, and a plurality of amplifier stages connected in parallel between the input port and the output port. Each of the amplifier stages comprises a common source field effect transistor (CSFET) and at least two common gate field effect transistors (CGFETs) coupled in series with a drain of the common source FET. At least one of the common gate field effect transistors of each stage includes a stabilizing network connected between drain and source diffusions.

An excessive voltage rise of load voltage, caused by an impedance mismatching on a transmission path, is prevented, and high-frequency power is regenerated. A parallel impedance is connected to the transmission path during the voltage rise, thereby regenerating voltage caused by a standing wave and preventing excessive load voltage, together with enhancing energy usage efficiency. Establishing the parallel impedance for the load impedance, on the transmission path between the high-frequency amplifier circuit of the high-frequency power supply device and the high-frequency load, reduces impedance at the connecting position to prevent generation of excessive voltage on the transmission path, and high-frequency power is regenerated from the transmission path by the parallel impedance.