Abstract: Amplifier having input power protection. In some embodiments, an amplifier circuit can include an input node and an output node, and an amplifier implemented between the input node and the output node. The amplifier circuit can further include a bias circuit configured to provide a bias signal to the amplifier. The amplifier circuit can further include a protection circuit configured to generate a detected voltage representative of a peak of a radio-frequency signal present at the input node. The protection circuit can be further configured to enable a protection mode when the detected voltage is greater than a first threshold value and to disable the protection mode when the detected voltage is less than a second threshold value that is less than the first threshold value.

Abstract: A broadband power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

Abstract: Radio-frequency splitter circuits, devices and methods. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

Abstract: A power splitter that amplifies an input radio-frequency (RF) signal. The power splitter uses a single transistor in a common emitter stage of a cascode amplifier and two or more common base stages of the cascode amplifier to amplify and to split the input RF signal. A common base biasing signal can be used to simultaneously enable two or more of the common base stages to generate two or more amplified RF output signals.

Abstract: Amplifier having input power protection. In some embodiments, an amplifier circuit can include an input node and an output node, and an amplifier implemented between the input node and the output node. The amplifier circuit can further include a bias circuit configured to provide a bias signal to the amplifier. The amplifier circuit can further include a protection circuit configured to generate a detected voltage representative of a peak of a radio-frequency signal present at the input node. The protection circuit can be further configured to enable a protection mode when the detected voltage is greater than a first threshold value and to disable the protection mode when the detected voltage is less than a second threshold value that is less than the first threshold value.

Abstract: Radio-frequency splitter circuits, devices and methods. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

Abstract: A power splitter that amplifies an input radio-frequency (RF) signal. The power splitter uses a single transistor in a common emitter stage of a cascode amplifier and two or more common base stages of the cascode amplifier to amplify and to split the input RF signal. A common base biasing signal can be used to simultaneously enable two or more of the common base stages to generate two or more amplified RF output signals.

Abstract: Broadband power splitter. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

Abstract: A power splitter that amplifies an input radio-frequency (RF) signal. The power splitter uses a single transistor in a common emitter stage of a cascode amplifier and two or more common base stages of the cascode amplifier to amplify and to split the input RF signal. A common base biasing signal can be used to simultaneously enable two or more of the common base stages to generate two or more amplified RF output signals.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Abstract: Broadband power splitter. In some embodiments, a power splitter can include an input port, a first output port and a second output port. The power splitter can further include a first signal path implemented between the input port and the first output port, and a second signal path implemented between the input port and the second output port. Each of the first and second signal paths can include a variable capacitance configured to provide a plurality of capacitance values that result in different frequency responses of the respective signal path.

Abstract: A power splitter that amplifies an input radio-frequency (RF) signal. The power splitter uses a single transistor in a common emitter stage of a cascode amplifier and two or more common base stages of the cascode amplifier to amplify and to split the input RF signal. A common base biasing signal can be used to simultaneously enable two or more of the common base stages to generate two or more amplified RF output signals.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Abstract: Multiband power amplifier with cascode switching. A power amplification system can include a first transistor having a base configured to receive an input radio-frequency (RF) signal and having an emitter coupled to a ground potential. The power amplification system can include a plurality of second transistors. Each one of the plurality of second transistors can have a respective emitter coupled to a collector of the first transistor and can be configured to, when biased at a respective base, output an output RF signal at a respective collector. The power amplification system can further include a biasing circuit configured to bias one or more of the plurality of second transistors based on a control signal.

Abstract: Various implementations include circuits, devices and/or methods that provide open loop current limiting power amplifiers and the like. In some implementations, an open loop current clamp includes a trim module to provide a control value and a limiting source having respective input and output terminals. The input terminal is coupled to the trim module to receive the control value. The output terminal coupled to a control terminal of the first transistor to provide a limiting electrical level produced in response to the control value by the limiting source. The limiting electrical level substantially setting a first mode of operation for the first transistor such that the current draw of the first transistor is substantially determined by the first mode of operation and the limiting electrical level such that a voltage at an output terminal of the first transistor exerts reduced influence on the current draw.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Abstract: Multiband power amplifier with cascode switching. A power amplification system can include a first transistor having a base configured to receive an input radio-frequency (RF) signal and having an emitter coupled to a ground potential. The power amplification system can include a plurality of second transistors. Each one of the plurality of second transistors can have a respective emitter coupled to a collector of the first transistor and can be configured to, when biased at a respective base, output an output RF signal at a respective collector. The power amplification system can further include a biasing circuit configured to bias one or more of the plurality of second transistors based on a control signal.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

Abstract: In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.