A GaN-based high electron mobility transistor (HEMT) device includes a semiconductor structure comprising a channel layer and a barrier layer sequentially stacked on a substrate, a drain contact and a source contact on the barrier layer, and a gate contact on the barrier layer between the drain contact and the source contact. A sheet resistance of a drain access region and/or a source access region of the semiconductor structure is between 300 and 400 Ω/sq.

A GaN-based high electron mobility transistor (HEMT) device includes a semiconductor structure comprising a channel layer and a barrier layer sequentially stacked on a substrate, a drain contact and a source contact on the barrier layer, and a gate contact on the barrier layer between the drain contact and the source contact. A sheet resistance of a drain access region and/or a source access region of the semiconductor structure is between 300 and 400 Ω/sq.

CRLH lines including left-handed shunt inductors and left-handed series capacitors are provided on gate side transmission lines of a plurality of FETs.

An electronic device includes a network monitor configured to acquire network environment information related to a radio frequency (RF) transmission signal; a transceiver configured to generate an envelope signal of the RF transmission signal; a transmission (Tx) module including a power amplifier for receiving the RF transmission signal from the transceiver and amplifying the RF transmission signal; and an envelope tracking (ET) modulator configured to receive the envelope signal from the transceiver and to provide a bias of a power amplifier to correspond to the envelope signal, wherein the ET modulator determines a magnitude of the bias of the power amplifier based on the network environment information acquired by the network monitor.

A Doherty power amplifier and a device are disclosed. In a combiner of the Doherty power amplifier, a first input port and a termination port are open coupled by at least two coupled microstrip lines and/or a second input port and an output port are open coupled by at least two coupled microstrip lines. Therefore, a balanced amplitude bandwidth may be obtained and may be much broader than that of the existing solutions, in addition, a controllable size or a potentially small size may be realized. Furthermore, the Doherty power amplifier in this disclosure may provide large 2.sup.nd harmonic suppression to meet product spectrum mask requirements.

An RF amplifier utilizes first and second main amplifiers in a balanced amplifier configuration with first and second auxiliary amplifiers connected in parallel across the first and second main amplifiers, respectively. The main and the auxiliary amplifiers are biased such that the third-order nonlinearity components in the combined output current are reduced. A common or independent bias control circuit(s) control(s) the DC operating bias of the auxiliary amplifiers and establishes DC operating points on curves representing third-order nonlinear components within the drain current having a positive slope (opposite to the corresponding slope of the main amplifiers). This results in reduction of overall third-order nonlinear components in combined currents at the output. In another embodiment, a phase shift of an input to one auxiliary amplifier is used to provide a peak in minimization at a frequency associated with the phase shift.

An RF amplifier utilizes first and second main amplifiers in a balanced amplifier configuration with first and second auxiliary amplifiers connected in parallel across the first and second main amplifiers, respectively. The main and the auxiliary amplifiers are biased such that the third-order nonlinearity components in the combined output current are reduced. A common or independent bias control circuit(s) control(s) the DC operating bias of the auxiliary amplifiers and establishes DC operating points on curves representing third-order nonlinear components within the drain current having a positive slope (opposite to the corresponding slope of the main amplifiers). This results in reduction of overall third-order nonlinear components in combined currents at the output. In another embodiment, a phase shift of an input to one auxiliary amplifier is used to provide a peak in minimization at a frequency associated with the phase shift.

A power amplifier circuit includes a first impedance transformer circuit arranged to connect with a carrier device, and a second impedance transformer circuit arranged to connect with a peaking device. Both the first and the second impedance transformer circuit include a parallel impedance transformer arrangement.

A power amplifier circuit includes a first impedance transformer circuit arranged to connect with a carrier device, and a second impedance transformer circuit arranged to connect with a peaking device. Both the first and the second impedance transformer circuit include a parallel impedance transformer arrangement.

A TX/RX switch includes a power amplifier (PA), a Low Noise Amplifier (LNA), and an antenna connection. The PA is connected to a PA matching network that has a PA network impedance and a common PA-LNA impedance connected in one or more series-parallel combinations in different embodiments in a transmitting mode. The LNA is connected to a LNA matching network that has a LNA network impedance and the same common PA-LNA impedance connected in one or more series-parallel combinations in a receive mode. A mode switch can connect the common PA-LNA impedance in different configurations to enable the transmitting and receiving mode respectively. In some embodiments, the mode switch can short or open circuit the connection of the PA matching circuit or the LNA matching circuit to the antenna. In some embodiments, the mode switch can also turn power on or off to the PA or the LNA when the switch is in a mode where the respective amplifier is not selected. Accordingly, with specific design limitations on the common PA-LNA impedance combined with different mode switch configurations of the TX/RX switch components in either the TX or RX mode, the TX/RX switch operates within a design bandwidth without transmission lines embedded in the TX/RX switch circuitry and provides optimum power transfer from/to the antenna at the antenna connection with reduced noise.