The technology described in this document can be embodied in an apparatus that includes an amplifier that includes a first Zeta converter connected to a power supply and a load. The amplifier also includes a second Zeta converter connected to the power supply and the load. The second Zeta converter is driven by a complementary duty cycle relative to the first Zeta converter. The amplifier also includes a controller to provide an audio signal to the first Zeta converter and the second Zeta converter for delivery to the load.

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 configured to amplify a transmission signal; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier and the PA control circuit are stacked on the first principal surface, and the first circuit component is disposed on the second principal surface.

Provided are a PA output matching circuit, a RF front-end module and a wireless device. The circuit is used for connecting with a first PA output and a second PA output of an output stage of a push-pull PA, and comprises a load balun, a first DC blocking circuit, a second DC blocking circuit, a first feed circuit and a second feed circuit; the main coil of the load balun is provided with a first balun input and a second balun input; the first balun input is connected with the first PA output via the first DC blocking circuit, and the first balun input is connected with the first PA output via the first feed circuit; the second balun input is connected with the second PA output via the second DC blocking circuit, and the second balun input is connected with the second PA output via the second feed circuit.

Provided are a PA output matching circuit, a RF front-end module and a wireless device. The circuit is used for connecting with a first PA output and a second PA output of an output stage of a push-pull PA, and comprises a load balun, a first DC blocking circuit, a second DC blocking circuit, a first feed circuit and a second feed circuit; the main coil of the load balun is provided with a first balun input and a second balun input; the first balun input is connected with the first PA output via the first DC blocking circuit, and the first balun input is connected with the first PA output via the first feed circuit; the second balun input is connected with the second PA output via the second DC blocking circuit, and the second balun input is connected with the second PA output via the second feed circuit.

A circuit includes a first system-on-chip (SoC) driven by a first clock generator and a second SoC driven by a second clock generator where the first clock generator and the second clock generator have independent time bases. The first and second clock generators are synchronized using an RLC circuit external to the first clock generator and the second clock generator that converts an output of the first clock generator into current pulses and injects the current pulses into the second clock generator to pull an output of the second clock generator into synchronization with the output of the first clock generator. The RLC circuit converts a voltage output of the first clock generator into current pulses at the resonant frequency or specific harmonics of the output of the first clock generator. The second clock generator may include a ring oscillator into which the current pulses are injected.

A circuit includes a first system-on-chip (SoC) driven by a first clock generator and a second SoC driven by a second clock generator where the first clock generator and the second clock generator have independent time bases. The first and second clock generators are synchronized using an RLC circuit external to the first clock generator and the second clock generator that converts an output of the first clock generator into current pulses and injects the current pulses into the second clock generator to pull an output of the second clock generator into synchronization with the output of the first clock generator. The RLC circuit converts a voltage output of the first clock generator into current pulses at the resonant frequency or specific harmonics of the output of the first clock generator. The second clock generator may include a ring oscillator into which the current pulses are injected.

A radio frequency circuit includes a transmit power amplifier, a differential transmit signal path having first and second paths, and first and second baluns. The first balun can be configured to convert a single ended transmit signal into a differential transmit signal, and the second balun can be configured to convert the differential transmit signal back to a single ended transmit signal. The circuit can also include a pair of transmit filters between the first and second baluns and including a first transmit filter connected in the first path and a second transmit filter connected in the second path. The second balun cancels harmonic noise generated by the pair of transmit filters.

A power amplifier system for amplifying a radio frequency signal can have a driver transistor coupled to a radio frequency signal input. The system can also have a transformer balun with a main primary coil connected between the driver transistor and a voltage supply node of the power amplifier system, a secondary coil magnetically coupled to the main primary coil, and an additional primary coil configured to generate a feedback signal related to a signal induced in the main primary coil. A neutralization diode can be configured to use the feedback signal to reduce a gain variation resulting from variations in a voltage supplied from the voltage supply node of the power amplifier system. The neutralization diode can be connected between the additional primary coil and the driver transistor. Through envelope tracking, voltage supplied through the voltage supply node can change in relation to an envelope of the radio frequency signal.

A power amplifier system for amplifying a radio frequency signal can have a driver transistor coupled to a radio frequency signal input. The system can also have a transformer balun with a main primary coil connected between the driver transistor and a voltage supply node of the power amplifier system, a secondary coil magnetically coupled to the main primary coil, and an additional primary coil configured to generate a feedback signal related to a signal induced in the main primary coil. A neutralization diode can be configured to use the feedback signal to reduce a gain variation resulting from variations in a voltage supplied from the voltage supply node of the power amplifier system. The neutralization diode can be connected between the additional primary coil and the driver transistor. Through envelope tracking, voltage supplied through the voltage supply node can change in relation to an envelope of the radio frequency signal.

Various implementations include a common mode voltage controller for a self-boosting push pull amplifier. In some implementations, input signal are processed by: calculating, based upon the input signal, a maximum duty cycle to achieve a target differential in an output of the self-boosting push pull amplifier; calculating, based on the input signal, a set of control parameters associated with adjusting a common mode voltage of the output; and generating, based on the input signal, a pair of signals configured to adjust the common mode voltage of the output, wherein the pair of signals include a gain adjustment and offset based on the maximum duty cycle and the set of control parameters, and wherein the pair of signals are configured to maintain the target differential in the output of the self-boosting push pull amplifier as the common mode voltage is adjusted to a different operating point.