A signal modulation device comprising: an input for receiving a complex input signal (106) comprising an in-phase component signal and a quadrature-phase component signal, a sigma-delta modulator (110) for modulating the complex input signal at an oversampling clock rate (F1) into an intermediary signal (112), a numerical oscillator (60) for generating a phase signal (61) oscillating at a selected carrier frequency (FC), wherein the phase signal takes a finite number of quantized states, and a symbol mapping table (114) comprising a predefined quantized symbol for each quantized complex state of the intermediary signal and each quantized state of the phase signal, and operates at each oversampling clock period (F1) to select a quantized symbol (116) as a function of a current quantized complex state of the intermediary signal (112) and a current quantized state of the phase signal (61).

A method and apparatus is provided. The method includes determining a training data set comprising input and output data of a power amplifier, determining compensation data by regressing the training data using a frequency domain weighting function, storing the compensation data, and linearizing an output of the power amplifier using the stored compensation data.

A very high frequency (VHF) transceiver can include an amplitude and phase shift keying (APSK) modulator configured to modulate signals for transmission across a first VHF channel of a plurality of VHF channels used to communicate between or among aircraft and one or more ground stations. Each of the VHF channels can have a bandwidth of at least 8.33 kilo Hertz (kHz) with a data rate per Hertz (Hz) greater than or equal to 3 bits per second per Hz (bps/Hz). The VHF transceiver can include a power amplifier configured to amplify the modulated signals prior to the transmission. The VHF transceiver can include a linearity controller configured to control linearity of the power amplifier according to at least one of a Cartesian feedback amplifier linearization, pre-distortion amplifier linearization or feedforward amplifier linearization to mitigate nonlinear distortion associated with signals output by the power amplifier.

The application relates to the field of communications technologies, and disclose a signal amplification processing method and apparatus. The method includes setting multiple groups of parameter values for a signal decomposition parameter group, separately performing signal amplification processing based on each group of parameter values, obtaining a power amplification efficiency corresponding to each group of parameter values, obtaining a group of parameter values corresponding to a maximum power amplification efficiency in the power amplification efficiency corresponding to each group of parameter values, and setting the group of parameter values corresponding to the maximum power amplification efficiency as parameter values of the signal decomposition parameter group. Thus, the power amplification efficiency may be improved.

An envelope tracking RF transmitter calibration procedure calculates both a supply voltage to apply to a power amplifier for a modulated signal envelope to achieve ISO-gain, and a timing delay adjustment to time-align the applied supply voltage and the modulated signal to minimize distortion due to time delay error. An ISO-gain surface is calculated, as a function of the envelope of a modulated signal and the power amplifier supply voltage, for each of a plurality of desired gain values. As the envelope is swept through a predetermined range of values, demodulated outputs at predetermined points are sampled, and a set of non-linear functions relating the supply voltage to the envelope, which achieve the desired gain at the sampled points, are derived, using surface interpolation between the predetermined gain surface points. Data defining the functions are stored for use during transmitter operation. Distortion components in the transmitter output are detected, and are separated into even components representing time delay error distortion, and odd components representing transmitter saturation distortion. A timing delay value is calculated that minimizes the time delay error distortion.

An analog predistortion linearizer system with dynamic frequency compensation for automatically adjusting predistortion characteristics based on a detected frequency includes a frequency detector configured to generate at least one frequency detection signal in response to receiving an amplifier drive signal, the frequency detection signal including a frequency indicator that indicates the frequency of the amplifier drive signal. Moreover, the system also includes a controller communicatively coupled to the frequency detector and configured to generate a predistorter control signal in response to receiving the frequency detection signal from the frequency detector, and a predistorter communicatively coupled to i) the frequency detector and ii) the controller, the predistorter configured to generate a predistorted amplifier drive signal based on at least the predistorter control signal.

An adaptive power amplifier and a radio frequency transmitter thereof are described. The radio frequency transmitter is a transmitter to transmit a transmission signal for a wireless communication system. The radio frequency transmitter includes at least one direct-current (DC) to direct-current (DC) converter coupled to an external power supply device for operation, a digital-to-analog converter configured to convert a digital signal into an analog signal, a filter configured to filter a harmonic component of the analog signal to generate an input signal, a RF up-converter configured to up-convert the input signal according to a desired channel frequency for generating a modulated signal, and a power amplifying circuit coupled to the DC-to-DC converter and the external power supply device, for selectively receiving one of different supply voltages for operation, and amplifying the modulated signal to generate a RF output signal.

Envelope tracking power supply circuitry includes a look up table (LUT) configured to provide a target supply voltage based on a power envelope measurement. The target supply voltage is dynamically adjusted based on a delay between the power envelope of an RF signal and a provided envelope tracking supply voltage. The envelope tracking supply voltage is generated from the adjusted target supply voltage in order to synchronize the envelope tracking supply voltage with the power envelope of the RF signal.

Techniques and examples pertaining to variation calibration for envelope tracking on chip are described. Envelope tracking (ET) statistics among multiple wireless-capable mobile devices (e.g., smartphones) may be collected in laboratory. Optimal ET parameters may be determined based on ET statistics. An ET setting file may be generated for ET factory calibration. In production lines, the ET setting file may be loaded into each mobile device for ET factory calibration.

The embodiments described herein include amplifiers configured for use in radio frequency (RF) applications. In accordance with these embodiments, the amplifiers are implemented to generate a shaped envelope signal, and to apply the shaped envelope signal to transistor gate(s) of the amplifier to provide gate bias modulation. So configured, the shaped envelope signal may facilitate high linearity in the amplifier.