Apparatus and methods for reconfigurable power amplifiers are disclosed. In certain embodiments, a mobile device includes a transceiver configured to generate a first radio frequency signal of a first frequency band and a second radio frequency signal of a second frequency band, and a front-end system including a push-pull power amplifier configured to selectively amplify one of the first radio frequency signal or the second radio frequency signal based on a band control signal. The push-pull power amplifier includes an input balun, an output balun, and a pair of amplifiers coupled between the input balun and the output balun. The band control signal is operable to control an output capacitance of the pair of amplifiers.

A peak detector includes an asymmetrical latch having a first input and a second input; and a CMOS converter having a first input coupled to a first output of the asymmetrical latch, a second input coupled to a second output of the asymmetrical latch, and an output.

A Doherty amplifier includes a divider configured to divide an input signal into two signals, a first amplifier configured to amplify one of the two signals and output the amplified signal to a first node, a second amplifier configured to amplify the other of the two signals and output the amplified signal to a second node, a balun including lumped parameter elements and configured to output a signal obtained by combining the signal output from the first amplifier with the signal output from the second amplifier to a third node, and a path configured to DC-connect the first node to the second node, with the third node therebetween.

Certain aspects of the present disclosure generally relate to techniques and apparatus for operating a wireless receiver of the apparatus in a high linearity mode. An example method includes operating the apparatus in a first mode with transmission of a plurality of transmit signals. The method also includes attenuating a received signal via an attenuator while operating the apparatus in the first mode. The method further includes amplifying the attenuated signal with an amplifier while operating the apparatus in the first mode. For certain aspects, the method further involves operating the apparatus in a second mode, bypassing the attenuator while operating the apparatus in the second mode, and amplifying the received signal with the amplifier while operating the apparatus in the second mode.

The radio-frequency differential circuit includes an input balun, an output balun, a first differential amplifying circuit, a second differential amplifying circuit, a first linear feedback circuit and a second linear feedback circuit; the first differential amplifying circuit is arranged between a first output end of the input balun and a first input end of the output balun; the second differential amplifying circuit is arranged between a second output end of the input balun and a second input end of the output balun; a first end of the first linear feedback circuit is connected with the input balun, a second end of the first linear feedback circuit is connected with the first differential amplifying circuit; a first end of the second linear feedback circuit is connected with the input balun, and a second end of the second linear feedback circuit is connected with the second differential amplifying circuit.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode. The first interdigital transducer electrode may be single-ended with a first input bus bar that receives an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The front-end module may include a low noise amplifier (LNA) that outputs a differential signal via a differential output and has a differential input connected to the acoustic wave filter. The LNA may include a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.

In a power amplifying module in which a plurality of differential amplifying circuits is mounted on a substrate, each of the differential amplifying circuits includes a chip device that includes at least two amplifiers, each of the at least two amplifiers amplifying a differential signal, a balun that includes a primary side winding wire and a secondary side winding wire, both ends of the primary side winding wire being connected to an output of the chip device, and a capacitor provided between a power feed point of the primary side winding wire and a reference potential. In at least one of the plurality of the differential amplifying circuits, the distance from one end of the primary side winding wire to the power feed point is different from the distance from the other end of the primary side winding wire to the power feed point.

Disclosed is an ultra-high frequency amplifier which includes a first conductor connected to an amplifier input terminal to receive an RF signal applied to the amplifier input terminal, a second conductor parallel to a first portion of the first conductor, a third conductor separated from the second conductor and parallel to a second portion of the first conductor, and a transistor including a gate terminal connected to one end of the second conductor, a first terminal connected to one end of the third conductor, and a second terminal connected to an amplifier output terminal, wherein the first conductor and the second conductor form a first balun to output a first balance signal based on the RF signal, the first conductor and the third conductor form a second balun to output a second balance signal based on the RF signal.

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode, and a low noise amplifier (LNA) that converts a differential input to a single-ended output with respect to ground. The first interdigital transducer electrode may be single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The LNA may have a differential input connected to the acoustic wave filter, a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter, and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.

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.