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.

Power amplifier systems with non-linear antenna impedance for load compensation are provided. In certain embodiments, a method of power amplification in a mobile device is provided. The method includes generating a radio frequency input signal using a transceiver, amplifying the radio frequency input signal to generate a radio frequency output signal using a power amplifier, and transmitting the radio frequency output signal using an antenna, including compensating the power amplifier for a change in output load in response to a change in signal power using a non-linear impedance versus output power characteristic of the antenna.

A power amplifier device includes: a first power supply terminal for inputting a first power supply voltage; a first transistor for power amplification that (i) includes a first gate to which a bias voltage is applied, and (ii) is supplied with power from the first power supply terminal; a second power supply terminal for inputting a second power supply voltage lower than the first power supply voltage; a second transistor for monitoring that (i) includes a second gate to which the bias voltage is applied, (ii) is supplied with power from the first power supply terminal or the second power supply terminal, and (iii) imitates an operation of the first transistor; and a bias circuit that is supplied with power from the second power supply terminal and generates and adjusts the bias voltage according to a drain current or a source current of the second transistor.

The present disclosure relates to amplifier circuitry (300) that includes a linear amplifier stage (110) that receives an input signal and outputs a first drive signal to an output node (302) and a switching amplifier stage (130) operable to output a second drive signal to the output node (302). A controller (340) is selectively operable in a first dual-amplifier mode, in which switching of the switching amplifier stage is controlled based on a current of the first drive signal, such that the current of the first drive signal does not exceed a first current threshold magnitude; and at least one other mode, in which the controller controls the switching amplifier stage such that the current of the first drive signal may exceed the first current threshold magnitude. The controller (340) selectively controls the mode of operation based on an indication (S.sub.SL) of signal level of the output signal.

An amplifier circuit includes a circuit path of serially connected complementary type transistors. First and second feedback loops include a loop amplifier, the transistors of the circuit path and a corresponding resistor.

Apparatus and methods for LNAs with mid-node impedance networks are provided herein. In certain configurations, an LNA includes a mid-node impedance circuit including a resistor and a capacitor electrically connected in parallel, a cascode device electrically connected between an output terminal and the mid-node impedance circuit, and a transconductance device electrically connected between the mid-node impedance circuit and ground. The transconductance device amplifies a radio frequency signal received from an input terminal. The LNA further includes a feedback bias circuit electrically connected between the output terminal and the input terminal and operable to control an input bias voltage of the transconductance device.

A circuit system for providing thermal stability to a transistor may include: a comparing circuit in electrical communication with the transistor for receiving a present voltage from the transistor and comparing a present voltage to a predetermined bias voltage; a logic gate electronically coupled to an output of the comparing circuit, the logic gate, gate having a high, open position and a low, closed position; and a heating element thermally coupled to the transistor and electrically coupled to the output of the comparing circuit, wherein when the present voltage is lower than the predetermined bias voltage, the gate is in the high, open position providing current to the heating element, and wherein when the present voltage is higher than the predetermine bias voltage the gate is in the low, closed position.

An output stage circuit comprising a bias voltage generator, a first amplifier circuit and a second amplifier circuit is provided. The bias voltage generator is coupled to an output terminal of the output stage circuit to generate a bias voltage according to an output voltage of the output terminal. The first amplifier circuit is coupled to the output terminal, a first power supply terminal and the bias voltage generator, receives a first pre-driving signal, a first predetermined voltage and the bias voltage, and determines whether to transmit a first voltage to serve as the output voltage. The second amplifier circuit is coupled to the output terminal, a second power supply terminal and the bias voltage generator, receives a second pre-driving signal, a second predetermined voltage and the bias voltage, and determines whether to transmit a second voltage to serve as the output voltage.

An electronic device is provided. The electronic device includes an antenna, an amplification circuit configured to amplify a signal to be transmitted through the antenna, a first sensing circuit configured to sense first information corresponding to a voltage value of power supplied to the amplification circuit, a second sensing circuit configured to sense second information corresponding to a current value of the power, and a protective circuit. The protective circuit may be configured to summate the first information and the second information into a single parameter, to determine whether a summation value corresponding to the single parameter deviates from an operating area determined by characteristics of the amplification circuit, and to adjust an output of the amplification circuit if the summation value deviates from the operating area.

Doherty radio frequency (RF) amplifier circuitry includes an input node, an output node, a main amplifier path, and a peaking amplifier path. The main amplifier path is coupled between the input node and the output node and includes a main amplifier. The peaking amplifier path is coupled in parallel with the main amplifier path between the input node and the output node, and includes a peaking amplifier and a peaking variable gain preamplifier between the input node and the peaking amplifier. The peaking variable gain preamplifier is configured to adjust a current provided to the peaking amplifier.