Aspects of this disclosure relate to systems and methods of performing dynamic impedance tuning. Certain aspects may be performed by or include a dynamic impedance matching network. The dynamic impedance matching network can determine a desired output power for a power amplifier, true power information for the power amplifier, and an output power delivered to a load by the power amplifier. In addition, the dynamic impedance matching network can determine whether the output power satisfies the true power information. Responsive to this determination, the dynamic impedance matching network may modify a load line impedance for the power amplifier using an impedance tuning network.

Aspects of this disclosure relate to detecting power associated with an individual carrier of a carrier aggregated signal. In an embodiment, an aggregated carrier including at least a first carrier and a second carrier is provided. An indication of power of the first carrier of the aggregated carrier is detected. Separately from detecting the indication of power of the first carrier, an indication of power of the second carrier of the aggregated carrier is detected. The power associated with a radio frequency (RF) signal provided to an RF source associated with the first carrier can be adjusted based on the indication of power of the first carrier.

Certain aspects of the present disclosure provide a directional coupler. In certain aspects, the directional coupler generally includes a first inductor and a second inductor wirelessly coupled to the first inductor. In certain aspects, the directional coupler generally includes an input port at a first terminal of the first inductor and a transmitted port at a second terminal of the first inductor. In certain aspects, the directional coupler generally includes a coupled port at a first terminal of the second inductor and an isolated port at a second terminal of the second inductor. In certain aspects, the directional coupler generally includes a first complex impedance component directly coupled to the isolated port and a second complex impedance component directly coupled to the coupled port.

Power amplification system for radio frequency communications, comprising a input port of an input radio frequency signal, an output port of an output radio frequency signal; a digital predistortion unit operatively interposed between the input port and the output port and quadrature modulation correction means operatively interposed between the digital predistortion unit and between at least one of the input port and the output port.

An RF transmitter with a power combiner and a differential amplifier is provided. The power combiner converts a differential output signal to a single-end output signal and transmits the single-end output signal to the antenna. The differential amplifier includes common-source input transistors, common-gate output transistors and a switch module. The common-source input transistors amplify a differential input signal and output an amplified differential signal. The common-gate output transistors, including sources electrically coupled to the common-source input transistors and drains electrically coupled to the power combiner, generate the differential output signal according to the amplified differential signal. The switch module is electrically coupled between the gates. The switch module electrically couples the gates of the common-gate output transistors if the RF transmitter is in operation and electrically isolates the gates if the RF receiver is in operation.

A directional coupler disclosed herein may include a main line provided on a substrate, the main line having a first end connected to an input port and a second end connected to an output port. The coupler may include a coupled line disposed on the substrate, the coupled line having a first end connected to a coupled port and a second end to an isolated port. The main line is electrically isolated from the coupled line. The coupled line includes multiple turns forming a winding, and a portion of the winding overlaps with the main line. The coupled line forms a plurality of windings inductively coupled with the main line. The main line and the coupled line are routed to propagate electric signals on both lines in a same direction, and enhance inductive coupling by mutual inductance.

A RF-digital hybrid mode power amplifier system for achieving high efficiency and high linearity in wideband communication systems is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier in the RF domain. The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers and multi-channels. As a result, the digital hybrid mode power amplifier system is particularly suitable for wireless transmission systems, such as base-stations, repeaters, and indoor signal coverage systems, where baseband I-Q signal information is not readily available.

An RF transmitter with a power combiner and a differential amplifier is provided. The power combiner converts a differential output signal to a single-end output signal and transmits the single-end output signal to the antenna. The differential amplifier includes common-source input transistors, common-gate output transistors and a switch module. The common-source input transistors amplify a differential input signal and output an amplified differential signal. The common-gate output transistors, including sources electrically coupled to the common-source input transistors and drains electrically coupled to the power combiner, generate the differential output signal according to the amplified differential signal. The switch module is electrically coupled between the gates. The switch module electrically couples the gates of the common-gate output transistors if the RF transmitter is in operation and electrically isolates the gates if the RF receiver is in operation.

An exemplary system comprises a linearizer module, a first upconverter module, a power amplifier module, a signal sampler module, and a downconverter module. The linearizer module may be configured to receive a first intermediate frequency signal and to adjust the first intermediate frequency signal based on a reference signal and a signal based on a second intermediate frequency signal. The first upconverter module may be configured to receive and up-convert a signal based on the adjusted first intermediate frequency signal to a radio frequency signal. The power amplifier module may be configured to receive and amplify a power of a signal based on the radio frequency signal. The signal sampler module may be configured to sample a signal based on the amplified radio frequency signal. The downconverter module may be configured to receive and down-convert a signal based on the sampled radio frequency signal to the second intermediate frequency signal.

A compound semiconductor device includes: a GaN-based channel layer; a barrier layer of nitride semiconductor above the channel layer; and a cap layer of nitride semiconductor above the barrier layer, wherein the cap layer includes: a first region doped with Fe; and a second region above the first region, a concentration of Fe in the second region being lower than a concentration of Fe in the first region.