An electronic device may include wireless circuitry with a baseband processor, a transceiver circuit, a front-end module, and an antenna. The front-end module may include amplifier circuitry such as a low noise amplifier for amplifying received radio-frequency signals. The amplifier circuitry is operable in a non-carrier-aggregation mode and a carrier aggregation mode. The amplifier circuitry may include an input transformer that is coupled to multiple amplifier stages such as a common gate amplifier stage, a cascode amplifier stage, and a common source amplifier stage. The common gate amplifier stage may include switches for selectively activating a set of cross-coupled capacitors to help maintain input impedance matching in the non-carrier-aggregation mode and the carrier-aggregation mode. The common source amplifier stage may include additional switches for activating and deactivating the common source amplifier stage to help maintain the gain in the non-carrier-aggregation mode and the carrier-aggregation mode.

Low noise amplifiers (LNAs) with low noise figure are provided. In certain embodiments, an LNA includes a single-ended LNA stage including an input for receiving a single-ended input signal from an antenna and an output for providing a single-ended amplified signal, a balun for converting the single-ended amplified signal to a differential signal, and a variable gain differential amplification stage for amplifying the differential signal from the balun. Implementing the LNA in this manner provides low noise figure, high gain, flexibility in controlling gain, and less sensitivity to ground/supply impedance.

A high-frequency circuit includes a power amplifier for a communication band A, and a power amplifier for a communication band B. Transmission in the communication band A, transmission in the communication band B, and reception in the communication band C can be simultaneously used. A frequency range of intermodulation distortion generated between a second harmonic wave of a transmission signal of the communication band A and a fundamental wave of a transmission signal of the communication band B, overlaps with at least part of a reception band of the communication band C. The power amplifier includes amplifying elements and an output trans including coils. One end of the coil is connected with an output of the amplifying element, the other end of the coil is connected with an output of the amplifying element, and one end of the coil is connected with an output terminal of the power amplifier.

A power amplifier comprises a first amplification stage having an input terminal receiving a radio frequency (RF) signal to be amplified and having a first coupling unit, a second amplification stage outputting an amplified radio frequency signal and having a second coupling unit and a third coupling unit providing RF feedback to the input terminal of the first amplification stage through an RF feedback path, the second coupling unit being coupled to the first coupling unit, and the third coupling unit being coupled to the first coupling unit.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier and the PA control circuit are stacked on the first principal surface, and the first circuit component is disposed on the second principal surface.

An active biconical antenna and a receive array comprising a combination of active biconical and Vivaldi antennas. In one configuration, the active biconical antenna includes upper and lower cones. Each cone has a respective truncated apex. First and second feed points are respectively connected to the truncated apexes of the upper and lower cones and to first and second conductors. The active biconical antenna further includes a buffer amplifier having respective input terminals connected to the first and second conductors. The buffer amplifier has an input impedance that is impedance matched to an antenna impedance at and above but not below a frequency f.sub.c and is higher than the antenna impedance at frequencies substantially less than f.sub.c. The buffer amplifier also has an output impedance that is impedance matched to a system impedance at frequencies both above and below f.sub.c. A length of the first and second conductors is less than a wavelength at the frequency f.sub.c.

An active biconical antenna and a receive array comprising a combination of active biconical and Vivaldi antennas. In one configuration, the active biconical antenna includes upper and lower cones. Each cone has a respective truncated apex. First and second feed points are respectively connected to the truncated apexes of the upper and lower cones and to first and second conductors. The active biconical antenna further includes a buffer amplifier having respective input terminals connected to the first and second conductors. The buffer amplifier has an input impedance that is impedance matched to an antenna impedance at and above but not below a frequency f.sub.c and is higher than the antenna impedance at frequencies substantially less than f.sub.c. The buffer amplifier also has an output impedance that is impedance matched to a system impedance at frequencies both above and below f.sub.c. A length of the first and second conductors is less than a wavelength at the frequency f.sub.c.

Provided are a PA output matching circuit, a RF front-end module and a wireless device. The circuit is used for connecting with a first PA output and a second PA output of an output stage of a push-pull PA, and comprises a load balun, a first DC blocking circuit, a second DC blocking circuit, a first feed circuit and a second feed circuit; the main coil of the load balun is provided with a first balun input and a second balun input; the first balun input is connected with the first PA output via the first DC blocking circuit, and the first balun input is connected with the first PA output via the first feed circuit; the second balun input is connected with the second PA output via the second DC blocking circuit, and the second balun input is connected with the second PA output via the second feed circuit.

A radio frequency circuit includes a transmit power amplifier, a differential transmit signal path having first and second paths, and first and second baluns. The first balun can be configured to convert a single ended transmit signal into a differential transmit signal, and the second balun can be configured to convert the differential transmit signal back to a single ended transmit signal. The circuit can also include a pair of transmit filters between the first and second baluns and including a first transmit filter connected in the first path and a second transmit filter connected in the second path. The second balun cancels harmonic noise generated by the pair of transmit filters.

There is provided a power amplifier arrangement for amplifying an input power signal to an output power signal. The power amplifier arrangement comprises a main amplifier having an input and an output. The power amplifier arrangement comprises at least one auxiliary amplifier, each having an input and an output. The power amplifier arrangement comprises a power divider having an input and outputs. The input of the power divider is configured to receive the input power signal. Each output of the power divider is connected to a respective input of the power amplifiers. The power amplifier arrangement comprises a Doherty combiner comprising at least one Ruthroff transformer and configured to combine all the outputs of the power amplifiers to, at an output of the Doherty combiner, produce the output power signal.