A package or a chip including a linear amplifier and a power amplifier is provided, wherein the linear amplifier is configured to receive an envelope tracking signal to generate an amplified envelope tracking signal, the power amplifier is supplied by an envelope tracking supply voltage comprising a DC supply voltage and the amplified envelope tracking signal, and the power amplifier is configured to receive an input signal to generate an output signal.

A transceiver circuit and related radio frequency (RF) circuit are provided. An RF circuit is coupled to a transceiver circuit configured to generate an envelope tracking (ET) target voltage. The RF circuit includes a tracker circuit and a power amplifier circuit(s). The tracker circuit may have inherent frequency-dependent impedance that can interact with a load current of the amplifier circuit(s) to cause degradation in an ET modulated voltage, which can lead to spectral distortions in an RF offset spectrum. As such, a voltage compensation circuit is provided in the transceiver circuit and configured to add a voltage compensation term in the ET target voltage. By adding the voltage compensation term into the ET target voltage, it is possible to compensate for the degradation in the ET modulated voltage, thus helping to reduce the spectral distortions in the RF offset spectrum and improve linearity and efficiency of the amplifier circuit(s).

This application relates to Class D amplifier circuits (200). A modulator (201) controls a Class D output stage (202) based on a modulator input signal (Dm) to generate an output signal (Vout) which is representative of an input signal (Din). An error block (205), which may comprise an ADC (207), generates an error signal () from the output signal and the input signal. In various embodiments the extent to which the error signal () contributes to the modulator input signal (Dm) is variable based on an indication of the amplitude of the input signal (Din). The error signal may be received at a first input (204) of a signal selector block (203). The input signal may be received at a second input (206) of the signal selector block (203). The signal selector block may be operable in first and second modes of operation, wherein in the first mode the modulator input signal is based at least in part on the error signal; and in the second mode the modulator input signal is based on the digital input signal and is independent of the error signal. The error signal can be used to reduce distortion at high signal levels but is not used at low signal levels and so the noise floor at low signal levels does not depend on the component of the error block (205).

Certain aspects of the present disclosure provide methods and apparatus for generating an envelope tracking power supply voltage. For example, certain aspects of the present disclosure provide an envelope tracking power supply having a linear amplifier having an output coupled to a power supply node of an amplifier, wherein a power supply node of the linear amplifier is coupled to a first voltage supply node. The envelope tracking power supply may also include a switch mode power supply having an output coupled to the power supply node of the amplifier. Certain aspects also include a circuit having a first switch coupled to the first voltage supply node and a second switch coupled to a second voltage supply node, wherein a power supply node of the switch mode power supply is coupled to the first switch and the second switch.

Disclosed herein are amplification systems that are dynamically biased based on a signal indicative of differential envelope of an input radio-frequency (RF) signal being amplified. The amplification systems include a cascode amplifier configured to amplify the RF signal to generate an output RF signal when one of the transistors of the cascode amplifier is biased by a combination of the input RF signal and a biasing signal while the other transistor of the cascode amplifier is biased by a processed differential envelope signal. The cascode amplifier also receives a combination of a processed differential envelope signal and a supply voltage to generate the output RF signal. The biasing signal can improve or enhance the linearity of amplification systems.

A method and operates for generating a boost control signal for a DC-DC-booster is described. An audio signal may be received comprising a plurality of audio sample values. The audio signal may be delayed for a delay time. A maximum-delayed-value of the audio sample values during the delay time may be determined. The boost control signal may be generated from the maximum of the non-delayed audio signal sample value and the maximum-delayed-value.

Apparatus and methods for envelope tracking systems with automatic mode selection are provided herein. In certain configurations, a power amplifier system includes a power amplifier configured to provide amplification to a radio frequency signal and to receive power from a power amplifier supply voltage, and an envelope tracker including a signal bandwidth detection circuit configured to generate a detected bandwidth signal based on processing an envelope signal corresponding to an envelope of the radio frequency signal. The envelope tracker further includes a switch bank configured to receive a plurality of regulated voltages, a filter configured to filter an output of the switch bank to generate the power amplifier supply voltage, and a mode control circuit configured to control a filtering characteristic of the filter based on the detected bandwidth signal.

A multi-standard transmitter architecture with digitally upconverted intermediate frequency (IF) outphased signals is disclosed. The transmitter architecture includes a Gallium Nitride (GaN) power amplifier (PA) circuit having a Current Mode Class-D (CMCD) configuration. The GaN PA circuit includes a lower switching device electrically coupled to an input to receive an input RF signal and an upper switching device to switchably electrically couple the first switching device to a power supply to drive an antenna circuit based on the input RF signal. Thus, a reconfigurable transmitter architecture is disclosed that utilizes a high-speed Gallium Nitride (GaN) driver to achieve a peak drain efficiency of at least 85% while delivering output power of 10 W at 1 GHz frequency, for example.

The representative embodiments discussed in the present disclosure relate to techniques in which the operating characteristics (e.g., power consumption) of a power amplifier in a transceiver may be regulated according to an operation mode of the transceiver. More specifically, in some embodiments, different LUTs may be employed for each mode of operation to suitably adjust the supply voltage (e.g., bias voltage) and/or quiescent current input to the power amplifier based on an input signal and a margin by which transmission standards are met. Further, in some embodiments, a method to calibrate a LUT for average power tracking and/or envelope tracking in a transceiver mode of operation may be employed to populate a LUT that may be used to suitably adjust the power and/or current consumption of the power amplifier.

Apparatus and methods of calibrating a power amplifier system to compensate for envelope amplitude misalignment are provided. In certain configurations, a method of calibrating a power amplifier system includes generating a supply voltage of a power amplifier using an envelope tracker based on shaping a scaled envelope signal using shaping data generated at a target gain compression, controlling a variable gain of a variable gain amplifier based on a gain control level signal, changing the variable gain by adjusting the gain control level signal using a calibration module, monitoring an output of the power amplifier to determine an amount of variable gain at which a detected gain compression of the power amplifier corresponds to the target gain compression of the shaping data, and calibrating the power amplifier system to compensate for envelope amplitude misalignment based on the determined amount of variable gain.