A power amplifier includes a power switching circuit, a driver circuit, and an amplifier circuit. The power switching circuit is configured to receive a first voltage and a second voltage, and provide the first voltage or the second voltage according to an operation mode of the power amplifier. The driver circuit is coupled to the power switching circuit. The driver circuit is configured to operate according to the first voltage or the second voltage and generate a driving signal according to an input signal. The amplifier circuit is coupled to the power switching circuit and the driver circuit. The amplifier circuit is configured to operate according to the first voltage or the second voltage and generate an output signal according to the driving signal.

A power amplifier includes a power switching circuit, a driver circuit, and an amplifier circuit. The power switching circuit is configured to receive a first voltage and a second voltage, and provide the first voltage or the second voltage according to an operation mode of the power amplifier. The driver circuit is coupled to the power switching circuit. The driver circuit is configured to operate according to the first voltage or the second voltage and generate a driving signal according to an input signal. The amplifier circuit is coupled to the power switching circuit and the driver circuit. The amplifier circuit is configured to operate according to the first voltage or the second voltage and generate an output signal according to the driving signal.

A transformer-based antenna switching network includes a transformer having a secondary winding that extends between a first terminal and a second terminal. The first terminal couples to ground through a first switch and connects to a first antenna. The second terminal couples to ground through a second switch and connects to a second antenna.

Various implementations include systems for amplifying input signals. In particular implementations, a system includes a common mode voltage controller configured to receive an input signal and output a pair of adjusted signals; a modulator that generates a pair of pulse width modulation (PWM) signals in response to the adjusted signals; and a self-boosting push pull amplifier configured to receive the PWM signals and generate an amplified output, wherein the self-boosting push pull amplifier is configured to generate a differential mode voltage representative of an amplified version of the input signal, wherein the adjusted audio signals generated by the common mode voltage controller include a dynamically adjusted gain and duty cycle offset that causes the self-boosting push pull amplifier to operate with a reduced common mode voltage.

An embodiment DC switching converter comprises first and second Zeta converters, each comprising an input stage, an output stage, a first switching stage, and a second switching stage. The input stage of each Zeta converter comprises a respective input inductor having a first terminal electrically coupled to the respective first switching stage. The input inductors of the input stages of the first and second Zeta converters are magnetically coupled in such a way that when current enters the terminal of the input inductor of the first Zeta converter that is coupled to the first switch stage of the first Zeta converter, a voltage induced by the coupled current is positive at the terminal of the input inductor of the second Zeta converter that is coupled to the first switching stage of the second Zeta converter.

An embodiment DC switching converter comprises first and second Zeta converters, each comprising an input stage, an output stage, a first switching stage, and a second switching stage. The input stage of each Zeta converter comprises a respective input inductor having a first terminal electrically coupled to the respective first switching stage. The input inductors of the input stages of the first and second Zeta converters are magnetically coupled in such a way that when current enters the terminal of the input inductor of the first Zeta converter that is coupled to the first switch stage of the first Zeta converter, a voltage induced by the coupled current is positive at the terminal of the input inductor of the second Zeta converter that is coupled to the first switching stage of the second Zeta converter.

A switching power amplifier includes logic circuitry that generates first and second components of a differential signal, based on received amplitude code and a delayed version of the same. The amplitude code includes a sign and a magnitude. When the sign is positive, a first logic path is configured to generate the first component based on the received amplitude code and the second logic path is configured to generate the second component based on the delayed amplitude code. When the sign is negative, the first logic path is configured to generate the first component based on the delayed amplitude code and the second logic path is configured to generate the second component based on the received amplitude code. The switching power amplifier further includes a differential-to-single ended conversion circuit configured to generate a single-ended signal based on the differential signal.

A Class D amplifier comprising a control circuit configured to receive an audio input signal and derive first, second and third PWM switching control signals therefrom, being supplied to respectively first, second and third switches of a driver, the first and second switches being serially arranged between first and second supply voltages, and having a common node coupled to an output terminal. The driver comprises a DC level shifter being configured to provide a reference voltage to a reference terminal in at least first and second states of operation, said reference voltage including a DC component at least substantially equidistant between the first and second supply voltages. Said third switch being included in a shunt path between the output and the reference terminal.

Methods and systems for power amplification with digital quantized power supply with multiple amplifiers are disclosed herein. In one embodiment, In one embodiment, a time-varying envelope signal is sampled, quantized and decomposed into several constituent signals that are individually amplified, and then combined to form a desired amplified version of the quantized time-varying envelope. Amplitude, phase and/or frequency characteristics of one or more of the signals and supply voltages V.sub.dd and source current of one or more amplifiers are digital controlled based on the information provided by quantization process and slow and fast power control information. Amplitude, phase and/or frequency characteristics of one or more of the constituent signals to be amplified are controlled to provide the desired amplitude, phase, frequency, and/or spectral characteristics of the desired quantized version of the time-varying envelope signal.

A power amplifying circuit includes a bias circuit that supplies a bias current or a bias voltage to a base of a first transistor, and at least one termination circuit that short-circuits a second-order harmonic of an amplified signal output from a collector of the first transistor to a ground voltage. An emitter of the first transistor is connected to ground. The bias circuit includes a second transistor. A collector of the second transistor is connected to the base of the first transistor. An emitter of the second transistor is connected to the emitter of the first transistor. A base of the second transistor is supplied with a predetermined voltage.