An envelope tracking system for controlling a power amplifier supply voltage includes envelope circuitry and a feed forward digital to analog converter (DAC) circuitry. The envelope circuitry is configured to generate a target envelope signal based on a selected power amplifier supply voltage. The feed forward DAC circuitry includes a voltage source circuitry and a selector circuitry. The voltage source circuitry is configured to generate a plurality of voltages. The selector circuitry is configured to select one of the plurality of voltages based at least on the target envelope signal. The feed forward DAC circuitry is configured to provide the selected voltage to a supply voltage input of a power amplifier that amplifies a radio frequency (RF) transmit signal.

Apparatus and methods for power amplifier power management are disclosed. In certain embodiments, a mobile device includes a transceiver that generates a radio frequency signal, a front-end system including a first power amplifier module that amplifies the radio frequency signal, and a power management system including an envelope tracking power management unit that provides an envelope tracking supply voltage to the first power amplifier module, and a first average power tracking power management unit that provides an average power tracking supply voltage to the first power amplifier module. The first power amplifier module is configured to selectively switch between the envelope tracking supply voltage and the average power tracking supply voltage.

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.

An apparatus is provided which comprises: a low-side switch; at least two high-side switches coupled to the low-side switch; a supply boost circuitry coupled to one of the at least two high-side switches; and a high-side switch selection circuit which is operable to enable one of the at least two high-side switches according to a relative difference between a signal and a threshold.

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are presented, where the amplifier can have a varying supply voltage. According to one aspect, the gate of the input transistor of the amplifier is biased with a fixed voltage whereas the gates of the other transistors of the amplifier are biased with variable voltages that are linear functions of the varying supply voltage. According to another aspect, the linear functions are such that the variable voltages coincide with the fixed voltage at a value of the varying supply voltage for which the input transistor is at the edge of triode. According to another aspect, biasing of the stacked transistors is such that, while the supply voltage varies, the drain-to-source voltage of the input transistor is maintained to a fixed value whereas the drain-to-source voltages of all other transistors are equal to one another.

An electronic device may include wireless circuitry with a processor that generates baseband signals, an upconversion circuit that upconverts the baseband signals to radio-frequency signals, a power amplifier, an antenna, and a transmit filter with a frequency dependent filter response coupled between the output of the power amplifier and the antenna. To help mitigate the frequency dependent filter response, the wireless circuitry may further include predistortion circuitry having an amplifier load response estimator that implements a baseband model of the filter response, an amplifier non-linearity estimator that models the non-linear behavior of the amplifier, and a control signal generator for adjusting the power amplifier based on the output of the amplifier load response estimator and the amplifier non-linearity estimator.

A distributed power management apparatus is provided. The distributed power management apparatus includes an envelope tracking (ET) integrated circuit (ETIC) and a distributed ETIC separated from the ETIC. The ETIC is configured to generate a number of ET voltages for a number of power amplifier circuits and the distributed ETIC is configured to generate a distributed ET voltage(s) for a distributed power amplifier circuit(s). In a non-limiting example, the number of power amplifier circuits and the distributed power amplifier circuit(s) can be disposed on opposite sides (e.g., top and bottom) of a wireless device. As such, in embodiments disclosed herein, the ETIC is provided closer to the power amplifier circuits and the distributed ETIC is provided closer to the distributed power amplifier circuit(s). By providing the ETIC and the distributed ETIC closer to the respective power amplifier circuits, it is possible to reduce trace inductance and unwanted signal distortion.

Distortion correction for fast supply voltage changes in a power amplifier is disclosed. In one aspect, analog predistortion in the power amplifier to maintain linearity of the power amplifier is based on a supply voltage, thereby avoiding a need to write into registers. Further, the supply voltage with its changes may be used to set the predistortion levels both for amplitude and phase. By using the supply voltage, long signals writing to registers in the power amplifier or power management circuit may be avoided, resulting in faster application of predistortion. The faster application of the predistortion works nicely with symbol or even sub-symbol adjustments to the supply voltage resulting in greater efficiency in the power amplifier.

Circuits and methods for use in amplifying amplitude and phase modulated signals. A circuit uses a digital controlled multi stage combiner, a signal phase discrete mapper and a combiner digital control circuit with N parallel signal feeding it. The signals resulting from N power amplifiers have phases with belonging to an alphabet with M discrete phases prior to being fed to the multi stage combiner. The phases of the N input signals are converted in an control signal generator into Ns sets of digital control signals to control N.Math.M sets of switches where the signals are selected according the phase and sent to the corresponding combiner in the M possible combiners. Each one combiner from the set of M combiner then combines these signals. A second stage with digital controlled combiner, combines into two sub-sets of signals the signals resulting from first stage and the resulting outputs of the combiner are then combined by a third combining digital controlled stage into the output signal. The signal amplifiers employed before the combining stage may be Class D or Class F amplifiers to provide high efficiency amplification of the signals.

Embodiments of this application provide an envelope tracking modulator, comprising: a linear amplification circuit, a coupling capacitor, a buck circuit, a circuit sensor, and an offset current generation circuit. An output end of the linear amplification circuit is coupled to a first end of the coupling capacitor, and a second end of the coupling capacitor is coupled to a power supply node. The offset current generation circuit is coupled to the first end and the second end of the coupling capacitor, and the offset current generation circuit is further coupled to a control end of the buck circuit. An input end of the circuit sensor is coupled to a line between the output end of the linear amplification circuit and the first end of the coupling capacitor, and an output end of the circuit sensor is coupled to the control end of the buck circuit.