Apparatus and methods for bias switching of power amplifiers are provided herein. In certain configurations, a power amplifier system includes a power amplifier that provides amplification to a radio frequency (RF) signal, a power management circuit that controls a voltage level of a supply voltage of the power amplifier, and a bias control circuit that biases the power amplifier. The power management circuit is operable in multiple supply control modes, such as an average power tracking (APT) mode and an envelope tracking (ET) mode. The bias control circuit is configured to switch a bias of the power amplifier based on the supply control mode of the power management circuit.

A circuit includes a transformer having a primary coil coupled to a first power amplifier (PA) and a second PA, and a secondary coil. The secondary coil supplies a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the primary coil with respect to a second phase of a second amplified constant-envelope signal in the primary coil. The circuit further includes load impedance coupled between a median point of the primary coil and ground. The load impedance is adjusted to match one of an impedance of the differential antenna, an impedance of the first PA, and an impedance of the second PA, based on the ripples detected by the ripple detector.

Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes an error amplifier that controls a voltage level of a power amplifier supply voltage of the power amplifier based on amplifying a difference between a reference signal and an envelope signal indicating an envelope of the RF signal. The envelope tracker further includes a multi-level switching circuit that generates an error amplifier supply voltage based on sensing a current of the error amplifier, and uses the error amplifier supply voltage to power the error amplifier.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier includes: an input terminal; an output terminal; first and second amplifying elements disposed parallel to the input terminal; and an output transformer connected between the output terminal and output terminals of the first and second amplifying elements. The PA control circuit is disposed on the second principal surface, and the first and second amplifying elements are both disposed on the first principal surface.

A barely Doherty dual envelope tracking (BD.sup.2E) circuit has a transmitter chain that includes an envelope tracking (ET) circuit that controls a Doherty dual power amplifier array. The ET circuit provides two control signals (supply voltage signals) that are used to control or modulate a carrier amplifier and a peaking amplifier independently of one another. The BD.sup.2E circuit includes an improved impedance inverter that isolates the peaking amplifier from the carrier amplifier to allow this independent control. By providing independent control, greater linearity may be provided while preserving the efficiency of the circuit.

Average power tracking (APT) systems with fast transient settling are disclosed. In certain embodiments, an APT system is used to provide a power amplifier supply voltage to a power amplifier that amplifies a radio frequency (RF) signal. The APT system controls the power amplifier supply voltage to track an average power of the RF signal, and generates a first regulated voltage based on a first average power tracking voltage level and a second regulated voltage based on a second average power tracking voltage level. The APT system includes a DC switch configured to receive the first regulated voltage and the second regulated voltage, and operable to change state to transition the power amplifier supply voltage from the first average power tracking voltage level to the second average power tracking voltage level.

Average power tracking (APT) systems with fast transient settling are disclosed. In certain embodiments, an APT system is used to provide a power amplifier supply voltage to a power amplifier that amplifies a radio frequency (RF) signal. The APT system controls the power amplifier supply voltage to track an average power of the RF signal, and includes a DC-to-DC converter that is assisted by an error amplifier in transitioning from one power amplifier supply voltage level to another power amplifier supply voltage level. Thus, the combination of a DC-to-DC converter with a fast changing error amplifier can swing enough AC voltage with a low enough slew rate to be able to rapidly transition the power amplifier supply voltage from one APT voltage level to another APT voltage level.

A radio frequency module includes: a module board including a first principal surface and a second principal surface on opposite sides of the module board; a transmission power amplifier configured to amplify a transmission signal; a first switch; and a first inductor included in a matching circuit connected between an output terminal of the transmission power amplifier and the first switch. The first inductor is disposed on the first principal surface, and the first switch is disposed on the second principal surface.

According to various embodiments of the disclosure, a portable communication device may include: a processor, a communication circuit, at least one first type antenna circuitry, and at least one second type antenna circuitry, wherein the at least one first type antenna circuitry may include an antenna array configured to transmit and/or receive a signal, a power amplifier configured to amplify a transmit signal and a low noise amplifier configured to amplify a received signal, the at least one second type antenna circuitry may include an antenna array configured to receive a signal and a low noise amplifier configured to amplify a received signal, the at least one second type antenna circuitry not including a power amplifier for amplifying a transmit signal, wherein the processor may be configured to control the portable communication device to transmit a transmit signal through the at least one first type antenna circuitry, and to receive a receive signal through at least one selected from the at least one first type antenna circuitry and the at least one second type antenna circuitry.

Power amplifiers with supply capacitor switching are provided herein. In certain embodiments, a power amplifier system includes a power amplifier that provides amplification to a radio frequency (RF) signal, a power management circuit that controls a voltage level of a supply voltage of the power amplifier, a supply capacitor having a first end connected to the supply voltage, and a bulk n-type field-effect transistor (NFET) switch. The power management circuit is operable in multiple supply control modes (for example, an average power tracking mode and an envelope tracking mode). Additionally, the bulk NFET switch is controlled based on the supply control mode of the power management circuit. The bulk NFET switch includes a ground NFET in series with a second end of the supply capacitor and a ground voltage, and a discharge NFET connected between the second end of the supply capacitor and the supply voltage.