A digital predistortion (DPD) system includes an input configured to receive an input signal. In some examples, a first signal path configured to generate a first signal based on the input signal. In some examples, an error model provider configured to generate an error model signal modeled after a gate bias error voltage associated with the DPD system. In some examples, a first combiner configured to combine the first signal and the error model signal to generate a first intermediate signal, and the DPD system generates an output signal based at least on the first intermediate signal.

A digital predistortion (DPD) system includes an input configured to receive an input signal. In some examples, a first signal path configured to generate a first signal based on the input signal. In some examples, an error model provider configured to generate an error model signal modeled after a gate bias error voltage associated with the DPD system. In some examples, a first combiner configured to combine the first signal and the error model signal to generate a first intermediate signal, and the DPD system generates an output signal based at least on the first intermediate signal.

A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.

A radio frequency apparatus includes a power amplifier circuit, a signal coupling circuit, an extraction circuit, and a harmonic filter circuit. The power amplifier circuit is configured to amplify a differential signal to output a to-be-filtered signal. The signal coupling circuit includes a primary side inductor and a secondary side inductor. The signal coupling circuit is configured to convert the to-be-filtered signal received by the primary side inductor into a single-ended signal outputted from the secondary side inductor. The extraction circuit has a center tap. The extraction circuit is configured to inductively couple to the primary side inductor and output a common mode signal from the center tap. The harmonic filter circuit is configured to perform a harmonic filtering on the single-ended signal according to the common mode signal, such that the secondary side inductor of the signal coupling circuit outputs a filtered signal.

A power amplifying circuit includes a first input terminal applied with a first bias voltage, a first amplifying circuit generating a first output signal and a second output signal according to an input signal and a first matching circuit combining the first output signal and the second output signal to generate an output signal. The first amplifying circuit includes a first transistor having a first electrode coupled to the first input terminal and a second electrode applied with a second bias voltage and a second transistor having a first electrode s coupled to the first input terminal and a second electrode applied with a third bias voltage. The first transistor generates the first output signal according to the first bias voltage and the second bias voltage. The second transistor generates the second output signal according to the first bias voltage and the third bias voltage.

A power amplifying circuit includes a first input terminal applied with a first bias voltage, a first amplifying circuit generating a first output signal and a second output signal according to an input signal and a first matching circuit combining the first output signal and the second output signal to generate an output signal. The first amplifying circuit includes a first transistor having a first electrode coupled to the first input terminal and a second electrode applied with a second bias voltage and a second transistor having a first electrode s coupled to the first input terminal and a second electrode applied with a third bias voltage. The first transistor generates the first output signal according to the first bias voltage and the second bias voltage. The second transistor generates the second output signal according to the first bias voltage and the third bias voltage.

An audio system has an amplifier for driving an audio actuator and includes a switched-mode power supply that draws power from a power source (e.g., battery) to supply power to the amplifier, a capacitor charged by the switched-mode power supply to supply power to the amplifier, and a feed-forward compressor that performs dynamic range compression of an audio input to provide an audio output for amplification by the amplifier. The compressor includes a sidechain frequency-biasing filter that generates a frequency-biased version of the audio input that is attenuated as frequency increases which causes the compressor to decrease the compression as frequency increases. A control block limits current drawn from the battery by the switched-mode power supply independent of audio input frequency, but the frequency-biasing filter enables the amplifier to service audio power transients greater than the current-limited power supply can supply by advantageously concurrently sourcing extra power from the capacitor.

A method of manufacture and structure for a monolithic single chip single crystal device. The method can include forming a first single crystal epitaxial layer overlying the substrate and forming one or more second single crystal epitaxial layers overlying the first single crystal epitaxial layer. The first single crystal epitaxial layer and the one or more second single crystal epitaxial layers can be processed to form one or more active or passive device components. Through this process, the resulting device includes a monolithic epitaxial stack integrating multiple circuit functions.

A method of manufacture and structure for a monolithic single chip single crystal device. The method can include forming a first single crystal epitaxial layer overlying the substrate and forming one or more second single crystal epitaxial layers overlying the first single crystal epitaxial layer. The first single crystal epitaxial layer and the one or more second single crystal epitaxial layers can be processed to form one or more active or passive device components. Through this process, the resulting device includes a monolithic epitaxial stack integrating multiple circuit functions.

A package or a chip including a linear amplifier and a power amplifier is provided, wherein the linear amplifier is configured to receive an envelope tracking signal to generate an amplified envelope tracking signal, the power amplifier is supplied by an envelope tracking supply voltage comprising a DC supply voltage and the amplified envelope tracking signal, and the power amplifier is configured to receive an input signal to generate an output signal.