A multi-amplifier envelope tracking (ET) apparatus is provided. The multi-amplifier ET apparatus includes an ET integrated circuit (ETIC). The ETIC includes a first voltage circuit that generates the first ET voltage based on a first supply voltage and a first time-variant target voltage. The ETIC also includes a second voltage circuit that generates the second ET voltage based on a second supply voltage and a second time-variant target voltage. In embodiments disclosed herein, the ETIC is configured to determine the first supply voltage and the second supply voltage in accordance to the first time-variant target voltage and the second time-variant target voltage, respectively. As a result, both the first and the second voltage circuits can operate with optimal efficiency, thus helping to improve overall operating efficiency of the multi-amplifier ET apparatus.

Aspects of this disclosure relate to symbol based envelope tracking. A voltage modulator circuit can generate an output bias voltage that tracks a root mean square symbol power of a radio frequency signal. A crest factor reduction circuit in a signal path that provides the radio frequency signal can adjust a crest factor reduction threshold such that the crest factor reduction threshold corresponds to the output bias voltage.

Envelope tracking (ET) voltage correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from a time-variant modulation vector and the power amplifier circuit(s) amplifies the RF signal(s) based on a modulated voltage and provides the amplified RF signal(s) to a coupled RF front-end circuit. Herein, the transceiver circuit is configured to apply an equalization filter to a selected form of the time-variant modulation vector to compensate for a voltage distortion filter created across a modulation bandwidth of the RF signal(s) by coupling the power amplifier circuit with the RF front-end circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth resulting from the voltage distortion filter to thereby improve efficiency and linearity of the power amplifier circuit(s) across the modulation bandwidth of the RF signal(s).

An amplification system configured to perform SPT and includes a DC/DC converter configured to output a power supply voltage Vcc1, a DC/DC converter configured to output a power supply voltage Vcc2, power amplifiers, and a switch configured to, in a first mode, selectively perform switching between a connection of the DC/DC converter and the power amplifier and a connection of the DC/DC converter and the power amplifier and, in a second mode, connect the DC/DC converter and the power amplifier and connect the DC/DC converter and the power amplifier.

Power amplifiers with supply capacitor switching are provided herein. In certain configurations, a mobile device includes a power management circuit that controls a voltage level of a supply voltage, and a front end system including a power amplifier that amplifies a radio frequency signal and that receives power from the supply voltage. The front end system further includes a supply capacitor having a first end electrically connected to the supply voltage, and a silicon-on-insulator (SOI) switch including a plurality of SOI field-effect transistors (FETs) electrically connected in series between a second end of the supply capacitor and a ground voltage. The SOI switch has an off state in which a first portion of the plurality of SOI FETs are controlled with the ground voltage and a second portion of the plurality of SOI FETs are controlled with a negative voltage less than the ground voltage.

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.

A delay-compensating power management circuit is provided. The power management circuit includes a power management integrated circuit (PMIC) configured to generate a time-variant voltage(s) based on a time-variant target voltage(s) for amplifying an analog signal(s) associated with a time-variant power envelope(s). A voltage processing circuit is provided in the power management circuit to determine a temporal offset, which can be positive or negative, between the time-variant power envelope(s) and the time-variant target voltage(s). Accordingly, the voltage processing circuit modifies the time-variant target voltage(s) to substantially reduce the determined temporal offset and thereby realign the time-variant target voltage(s) with the time-variant power envelope(s). By realigning the time variant target voltage(s) with the time-variant power envelope(s), it is possible to align the time-variant voltage(s) with the time-variant power envelope(s) to reduce distortions (e.g., amplitude clipping) during amplification of the analog signal.

A semiconductor device is provided in which power consumption is reduced and an increase in circuit area is inhibited. The semiconductor device includes a high frequency amplifier circuit, an envelope detection circuit, and a power supply circuit. The power supply circuit has a function of supplying a power supply potential to the high frequency amplifier circuit, an output of the high frequency amplifier circuit is connected to the envelope detection circuit, and an output of the envelope detection circuit is connected to the power supply circuit. The power supply circuit can reduce the power consumption by changing the power supply potential in accordance with the output of the high frequency amplifier circuit. The use of an OS transistor in the envelope detection circuit can inhibit an increase in circuit area.

Apparatus and methods for load modulated power amplifiers are provided. In certain embodiments, a load modulated power amplifier system includes a power amplifier that receives a radio frequency signal at an input and provides an amplified radio frequency signal at an output, and a controllable load impedance coupled to the output of the power amplifier. The controllable load impedance receives an envelope signal that changes in relation to an envelope of the radio frequency signal, and the envelope signal is operable to control an impedance of the controllable load impedance to modulate a load at the output of the power amplifier.

A device includes an amplifier having an input terminal and an output terminal. The input terminal is configured to receive a radio frequency (RF) input signal. The device includes an output network coupled to the output terminal of the power amplifier and a first passively tunable integrated circuit (PTIC) coupled to the output network. The first PTIC includes a direct-current (DC) bias voltage input terminal configured to receive a fixed bias voltage, a control signal input terminal configured to receive a time-varying control signal, wherein the fixed bias voltage in combination with the time-varying control signal sets an operating reference point of the first PTIC, and an input terminal electrically connected to the output terminal of the amplifier, wherein a change in an output voltage signal generated by the power amplifier causes the first PTIC to modify a first effective impedance of a load presented to the power amplifier via the output network.