A power amplifier system comprises an envelope tracker configured to generate a supply voltage that changes in relation to an envelope of a radio frequency signal, a power amplifier configured to amplify the radio frequency signal, and an adaptation circuit configured to adapt the supply voltage to provide operating power to the power amplifier. The adaptation circuit includes at least one Gallium Nitride field-effect-transistor configured to generate the operating power in response to an increased swing of the supply voltage and at least one linearizing circuit configured to linearize an operation of the Gallium Nitride field-effect-transistor.

An example apparatus includes: a compensation circuit including: a current compensation output, a first transistor with a first current terminal and a first control terminal, the first current terminal coupled to the current compensation output, and a resistor ladder with a tap terminal coupled to the first control terminal, a current mirror circuit having a mirror input and a mirror output, the mirror input coupled to the current compensation output, and a rectification circuit having an input coupled to the mirror output.

A notch circuit and a power amplifier module capable of reducing self-interference in a transceiver are provided. The transceiver includes a transmitter and a receiver, and the transmitter causes self-interference to the receiver. The transmitter includes a power amplifier module and the power amplifier module includes a notch circuit and a power amplifier. The notch circuit includes an inductor and a capacitor. The power amplifier amplifies an input transmission signal to generate an output transmission signal. The inductor receives a supply voltage. An amplitude of the supply voltage varies with the first input transmission signal. The capacitor is electrically connected to the inductor. The first output transmission signal (Tx_out1) is attenuated when a modulated frequency of the supply voltage is corresponding to a stopband.

Apparatus and methods for power amplifier envelope tracking systems with automatic control of a slew rate and a mode of an error amplifier of the envelope tracking system. The envelope tracker can include a signal bandwidth detection circuit that processes the envelope signal to generate a detected bandwidth signal, and a control circuit that controls the slew rate of the error amplifier based on the detected signal bandwidth.

Bias circuits and methods for silicon-based amplifier architectures that are tolerant of supply and bias voltage variations, bias current variations, and transistor stack height, and compensate for poor output resistance characteristics. Embodiments include power amplifiers and low-noise amplifiers that utilize a cascode reference circuit to bias the final stages of a cascode amplifier under the control of a closed loop bias control circuit. The closed loop bias control circuit ensures that the current in the cascode reference circuit is approximately equal to a selected multiple of a known current value by adjusting the gate bias voltage to the final stage of the cascode amplifier. The final current through the cascode amplifier is a multiple of the current in the cascode reference circuit, based on a device scaling factor representing the relative sizes of the transistor devices in the cascode amplifier and in the cascode reference circuit.

Provided is an electronic device that includes a communication processor; a transceiver electrically connected to the communication processor; a first power amplifier electrically connected to the transceiver; a first antenna electrically connected to the first power amplifier; and a first supply adjustor electrically connected to the communication processor and the first power amplifier. The communication processor can be set to perform a first determination about whether a carrier bandwidth part of a first signal transmitted through the first antenna exceeds a first threshold value, perform a second determination about whether the power of the first signal exceeds a second threshold value, select a first tracking mode as an envelope tracking mode or an average power tracking mode on the basis of at least a portion of the first determination and the second determination, and control the first supply adjustor using the selected first tracking mode.

Doherty power amplifiers with coupled line combiners are provided herein. In certain embodiments, a power amplifier system includes a carrier amplifier having a carrier output that provides a first radio frequency signal, a peaking amplifier having a peaking output that provides a second radio frequency signal, and a coupled line combiner including a first conductor line connected to the peaking output, a second conductor line electromagnetically coupled to the first conductor line, a third conductor line connected to the carrier output, and a fourth conductor line electromagnetically coupled to the third conductor line and in series with the second conductor line. The power amplifier system further includes an inductor in series with the fourth conductor line and the second conductor line and operable to provide a radio frequency output signal to an output terminal.

Embodiments described herein relate to an envelope tracking system that uses a single-bit digital signal to encode an analog envelope tracking control signal, or envelope tracking signal for brevity. In certain embodiments, the envelope tracking system can estimate or measure the amplitude of the baseband signal. The envelope tracking system can further estimate the amplitude of the envelope of the RF signal. The system can convert the amplitude of the envelope signal to a single-bit digital signal, typically at a higher, oversample rate. The single-bit digital signal can be transmitted in, for example, a low-voltage differential signaling (LVDS) format, from a transceiver to an envelope tracker. An analog-to-digital converter (ADC or A/D) can convert the single-bit digital signal back to an analog envelope signal. Moreover, a driver can increase the power of the A/D output envelope signal to produce an envelope-tracking supply voltage for a power amplifier.

A power management circuit supporting phase correction in an analog signal with reduced physical pins is disclosed. The power management circuit includes a power amplifier circuit configured to amplify an analog signal having a time-variant power envelope based on a modulated voltage. The power management circuit also includes an envelope tracking integrated circuit (ETIC) configured to generate the modulated voltage and a modulated phase correction voltage to thereby cause a phase change in the analog signal. The ETIC receives a modulated differential signal that includes a common signal and a differential signal and generates the modulated phase correction voltage and the modulated voltage based on the common signal and the differential signal, respectively. By modulating the common signal and the differential signal into the modulated differential signal, it is possible to reduce physical pins in the ETIC to thereby reduce cost and footprint of the power management circuit.

Systems and methods are provided for detecting water within an electronic power steering assembly. A sensor assembly includes a resistor and a water-sensitive capacitor arranged to provide a series resistor-capacitor (RC) network having a cut-off frequency that is a function of a capacitance of the water-sensitive capacitor. An oscillator provides an excitation to the series RC network having a known frequency, such that the series RC network provides an output in response to the excitation. An envelope detector receives the output of the series RC network and generates an output representing an amplitude of the output of the series RC network. A microcontroller determines if water is present within the electronic power steering assembly from the amplitude of the output of the series RC network.