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.

A device includes a first amplifier coupled to a first signal conduction path and a second amplifier coupled to a second signal conduction path. A first coupler is coupled to the first signal conduction path. The first coupler is configured to produce an output signal based on a first signal carried by the first signal conduction path. A delay element is configured to impose a phase delay on the output signal of the first coupler to generate a delayed output signal. The device includes a second coupler coupled to the second signal conduction path. The second coupler is connected to the delay element and configured to inject the delayed output signal into the second signal conduction path.

Apparatus and methods for an improved-efficiency Doherty amplifier are described. The Doherty amplifier may include a two-stage peaking amplifier that transitions from an “off” state to an “on” state later and more rapidly than a single-stage peaking amplifier used in a conventional Doherty amplifier. The improved Doherty amplifier may operate at higher gain values than a conventional Doherty amplifier, with no appreciable reduction in signal bandwidth.

Circuit and methods using a single low-noise amplifier (LNA) to provide amplification for a wide band of RF frequencies while maintaining high gain and a low noise factor. Embodiments include an amplifier circuit including an input signal path for receiving a wideband RF signal; a switched inductor tuning block coupled to the input signal path and configured to selectively couple one of a plurality of inductances to the input signal path; and an amplifier coupled to the switched inductor tuning block and configured to receive the RF signal after passage through the selected coupled inductance. The switched inductor tuning block includes a plurality of selectable branches, each including an RF input switch; an RF output switch; an inductor coupled between the RF input switch and the RF output switch; and first and second shunt switches coupled between a respective terminal of the inductor and circuit ground.

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.

Examples of an amplifier includes an input divider section having a first path and a second path for branching of an input signal, wherein a passing phase at the first path and a passing phase at the second path are different; a first amplifying element that amplifies a signal input to the first path; a second amplifying element that amplifies a signal input to the second path; an output synthesizing section that performs synthesis of an output of the first amplifying element and an output of the second amplifying element with a third path for transmitting the output of the first amplifying element and a fourth path for transmitting the output of the second amplifying element, wherein a passing phase at the third path and a passing phase at the fourth path are different; and an electromagnetic coupling section that establishes electromagnetic coupling of two signals.

A radio-frequency module includes a module substrate and a power amplification circuit that includes first to fourth amplification elements, a transformer including primary and secondary coils, an output terminal to which the secondary coil is connected, and a circuit component disposed on the module substrate. Output terminals of the first and third amplification elements and output terminals of the second and fourth amplification elements are respectively connected to a first terminal and a second terminal of the primary coil. A capacitor is connected to a wiring line path connected between the output terminal of the first amplification element and the first terminal of the primary coil and to a wiring line path connected between the output terminal of the second amplification element and the second terminal of the primary coil. The primary or secondary coil includes a conductive layer surrounding at least part of the circuit component.

A Doherty amplifier including a main amplifier and a peak amplifier is mounted on a package substrate. A low noise amplifier is further mounted on the package substrate. A transmit/receive switch switches in terms of time between a transmission connection state in which an output signal of the Doherty amplifier is supplied to an antenna and a reception connection state in which a signal received by the antenna is inputted to the low noise amplifier.

According to an aspect, there is provided a method for power-amplification of a transmission signal, comprising: obtaining the transmission signal with phase and amplitude modulation; generating a power-amplified polar signal for approximating a power-amplified transmission signal by power-amplifying a first constant-envelope signal with one of two or more first amplification factors based on the transmission signal; generating an outphasing pair of a first power-amplified outphasing signal and a second power-amplified outphasing signal based on the transmission signal; and combining the power-amplified polar signal, the first power-amplified outphasing signal and the second power-amplified outphasing signal to provide the power-amplified transmission signal.

Disclosed is a dual-band coupling low-noise amplifying circuit and an amplifier, which comprises an input frequency dividing circuit, a high-frequency amplifying circuit, a low-frequency amplifying circuit and an output combining circuit. The input frequency dividing circuit includes a first duplexer, a first capacitor and a second capacitor, and the output combining circuit includes a second duplexer, a third capacitor and a fourth capacitor. The input frequency dividing circuit divides the received radio frequency signals into high-frequency signals and low-frequency signals, then inputs the high-frequency signals into the high-frequency amplifying circuit for power amplification, and inputs the low-frequency signals into the low-frequency amplifying circuit for power amplification, and outputs the high-frequency signals and the low-frequency signals after power amplification through the output combining circuit.