An in-band extraction unit is configured to extract an in-band from an output signal. An out-band extraction unit is configured to extract at least one pair of out-bands including a low frequency side out-band and a high frequency side out-band from the output signal. An ADC is configured to convert the extracted in-band and out-bands to digital signals. A signal processing unit is configured to process information included in the digital signals converted by the analog to digital converter and adjust an operation of predistorting an input baseband digital signal to generate the output signal.

Preventing RF signal distortion and signal error producing memory events in a Radio Frequency (RF) power amplifier (RFPA). An element, disposed prior to the Radio Frequency (RF) power amplifier (RFPA) in a signal path of a RF signal input to the RFPA, may enforce a maximum allowable amplitude in a high PAPR instantaneous high peak of the RF signal. An element may also increase or supplement a bias of the Radio Frequency (RF) power amplifier (RFPA) when a high PAPR instantaneous high peak is detected in the RF signal prior to receipt by the RFPA. Additionally, a first element operable detects when an instantaneous output voltage of the Radio Frequency (RF) power amplifier (RFPA) is below a predetermined voltage, and in response, a second element supplies additional current to prevent the output voltage of the RFPA from falling below a predetermined threshold voltage.

A power amplifier comprising: a first amplifier; a second amplifier, wherein the first and second amplifiers are arranged in parallel; an analogue pre-distortion network; a first coupler; and a second coupler, wherein the first coupler is configured to receive an input signal, direct said input signal to the first amplifier, and direct a first pre-distortion signal to the analogue pre-distortion network, wherein the first pre-distortion signal comprises a first distortion component generated at the input of the first amplifier, and the analogue pre-distortion network is configured to receive the first pre-distortion signal and manipulate its amplitude and/or phase to obtain a manipulated first pre-distortion signal, and the second coupler is configured to direct the manipulated first pre-distortion signal to the second amplifier.

A power management circuit operable with group delay is provided. The power management circuit includes a transceiver circuit configured to generate a digital target voltage and digitally delay the digital target voltage to generate multiple delayed digital target voltages. Accordingly, the transceiver circuit can generate a windowed digital target voltage in multiple delay tolerance windows based on the delayed digital target voltages. Since the windowed digital target voltage can tolerate a certain amount of group delay in each of the group delay tolerance windows, an envelope tracking (ET) voltage generated based on an analog version of the windowed digital target voltage can therefore tolerate the group delay in each of the group delay tolerance windows as well. As a result, it is possible to avoid distortion in the ET voltage to help improve performance of the power management circuit.

A compound semiconductor device includes a carrier supply layer, a channel layer disposed over the carrier supply layer and configured to include InGaAs, and an etching stopper layer disposed over the channel layer, and configured to include a first layer disposed over the channel layer and configured to include In.sub.x1Ga.sub.1-x1P, and a second layer disposed over the first layer and configured to include In.sub.x2Ga.sub.1-x2P, wherein x1 is greater than 0 and less than or equal to 1, x2 is greater than or equal to 0 and less than 1, and x1 is greater than x2.

A digital pre-distortion method for a multiband signal, an electronic device and a non-transitory computer-readable storage medium are disclosed. The digital pre-distortion method may include: determining a possible power amplifier distortion according to configuration of a signal issued by a cell; selecting a basis function of pre-distortion according to the possible power amplifier distortion; solving, according to a pre-collected reference multiband signal and a corresponding feedback signal, the selected basis function to obtain a pre-distortion parameter; and processing an input multiband signal according to the selected basis function and the pre-distortion parameter to generate a pre-distortion signal.

An object is to provide a method and a system of adjusting a power amplifier which makes it possible to adjust a linearizer using signals of two carriers by the same power, to reduce the influence of the non-linearity on a multicarrier signal compared with the conventional. A method of adjusting a power amplifier, the power amplifier including a linearizer to reduce an intermodulation caused by non-linearity of the power amplifier, includes: inputting two signals generated by a signal generator into the power amplifier; measuring power of each order of first intermodulations of the two signals output from the power amplifier; calculating a power sum of second intermodulations by the plurality of signals using the measured power of each order of the first intermodulations; and adjusting the linearizer so that the power sum of the second intermodulations by the plurality of signals takes a minimum value or at most a predetermined value.

Radio frequency systems and methods adjust power amplifier operation based on power amplifier operating mode or power level to achieve a tradeoff between improved linearity at lower power levels and improved out of band noise performance and coexistence at higher power levels.

One or more aspects of the techniques and models described herein provide for bidirectional recurrent neural network (BiRNN)-based digital pre-distortion techniques for radio frequency (RF) power amplifiers (PAs). As an example, a digital pre-distorter (DPD) system may implement residual learning and long short-term memory (LSTM) projection layer features to reduce computational complexity and memory requirements. Implementing the described unconventional techniques of applying residual learning in RNN (e.g., in BiLSTM), using LSTM projection to develop a DPD structure, or both, may provide several advantages over preexisting techniques. For instance, the complexity in training and pre-distortion may be reduced and significantly less memory may be required to store the DPD neural network coefficients (e.g., while achieving similar or better linearization performance compared to other LSTM models). Further, faster training convergence speed may be achieved (e.g., compared to other LSTM models).

An integrated circuit operable to measure an impedance presented to a transmitter path of the integrated circuit and a method thereof are provided. The integrated circuit includes a directional coupler that has an input port, a through port, a coupled port, and an isolation port. The integrated circuit also includes a power amplifier coupled to the input port of the directional coupler, a power detector configured to measure output levels from the coupled port and the isolation port of the directional coupler, a reference signal generator coupled to the isolation port of the directional coupler, and a vector modulator configured to adjust a phase of a signal generated from the power amplifier.