Abstract: An apparatus is disclosed for waveform-tailored average power tracking. In an example aspect, the apparatus includes an amplifier, a power converter, and an average power tracking module. The amplifier is configured to amplify radio-frequency signals using a supply voltage. The radio-frequency signals have different waveforms. The power converter is coupled to the amplifier and configured to provide the supply voltage. The average power tracking module is coupled to the power converter and configured to adjust the supply voltage according to the different waveforms to cause the supply voltage to vary across at least two waveforms of the different waveforms for related average output powers.

Abstract: An apparatus is disclosed for waveform-tailored average power tracking. In an example aspect, the apparatus includes an amplifier, a power converter, and an average power tracking module. The amplifier is configured to amplify radio-frequency signals using a supply voltage. The radio-frequency signals have different waveforms. The power converter is coupled to the amplifier and configured to provide the supply voltage. The average power tracking module is coupled to the power converter and configured to adjust the supply voltage according to the different waveforms to cause the supply voltage to vary across at least two waveforms of the different waveforms for related average output powers.

Abstract: An amplifier circuit includes an amplifier configured to receive a radio frequency (RF) input signal from an input node, a bias circuit comprising a reference transistor coupled between a reference current source and ground, and a bias transistor coupled to the reference transistor and configured to generate a main bias current to bias the amplifier, an input power sense circuit coupled to the input node, and an additional transistor coupled to the input power sense circuit and to the bias transistor, the additional transistor configured to generate an additional bias current to bias the amplifier, the additional bias current responsive to a power level of the RF input signal.

Abstract: An apparatus is disclosed for waveform-tailored average power tracking. In an example aspect, the apparatus includes an amplifier, a power converter, and an average power tracking module. The amplifier is configured to amplify radio-frequency signals using a supply voltage. The radio-frequency signals have different waveforms. The power converter is coupled to the amplifier and configured to provide the supply voltage. The average power tracking module is coupled to the power converter and configured to adjust the supply voltage according to the different waveforms to cause the supply voltage to vary across at least two waveforms of the different waveforms for related average output powers.

Abstract: Certain aspects of the present disclosure are directed to an amplifier. The amplifier may include a transistor coupled to an output of the amplifier, and a resonator coupled between the output of the amplifier and a reference potential node, a resonant frequency of the resonator being set to be at a subharmonic of a fundamental frequency of the amplifier, and an impedance of the resonator being greater than a load impedance of the amplifier at the fundamental frequency of the amplifier.

Abstract: An amplifier circuit includes an amplifier configured to receive a radio frequency (RF) input signal from an input node, a bias circuit comprising a reference transistor coupled between a reference current source and ground, and a bias transistor coupled to the reference transistor and configured to generate a main bias current to bias the amplifier, an input power sense circuit coupled to the input node, and an additional transistor coupled to the input power sense circuit and to the bias transistor, the additional transistor configured to generate an additional bias current to bias the amplifier, the additional bias current responsive to a power level of the RF input signal.

Abstract: Certain aspects of the present disclosure are directed to an amplifier. The amplifier may include a transistor coupled to an output of the amplifier, and a resonator coupled between the output of the amplifier and a reference potential node, a resonant frequency of the resonator being set to be at a subharmonic of a fundamental frequency of the amplifier, and an impedance of the resonator being greater than a load impedance of the amplifier at the fundamental frequency of the amplifier.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for current-limiting protection of an amplifier, such as a power amplifier in a radio frequency (RF) front-end. One example current-limiting circuit generally includes a node coupled to a current source, a plurality of current-sinking devices coupled to the node, one or more switches coupled between the node and at least one of the plurality of current-sinking devices, and a bias circuit having an input coupled to the node and an output for coupling to an input of the amplifier.

Abstract: An amplifier circuit includes a driver amplifier implemented on a silicon-on-insulator (SOI) substrate and configured to amplify a radio frequency (RF) signal, a bypass circuit implemented on the SOI substrate and configured to selectively bypass the driver amplifier, an output coupled to the driver amplifier and the bypass circuit, an interconnect configured to couple the output to a gallium arsenide (GaAs) substrate, and a power amplifier implemented on the GaAs substrate and configured to amplify a signal received over the interconnect from the output.

Abstract: A circuit including a radio frequency (RF) amplifier including a transistor configured to receive an RF signal at its control terminal, a capacitor coupled to a first terminal of the transistor, an inductor coupled to a second terminal of the transistor, wherein the capacitor and inductor form a loop from the first terminal to the second terminal, wherein the loop bypasses a parasitic inductance between the second terminal and ground.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for operating a power amplifier. In one example, the apparatus includes a power amplifier configured to amplify an input signal having a frequency to produce a radio frequency (RF) output signal at an output and a harmonic tuning circuit coupled between a power supply and the power amplifier output, the harmonic tuning circuit configured to reduce a current or voltage provided to the power amplifier via a resonance at one or more harmonics of the frequency of the input signal.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for operating a power amplifier. In one example, the apparatus includes a power amplifier configured to amplify an input signal having a frequency to produce a radio frequency (RF) output signal at an output and a harmonic tuning circuit coupled between a power supply and the power amplifier output, the harmonic tuning circuit configured to reduce a current or voltage provided to the power amplifier via a resonance at one or more harmonics of the frequency of the input signal.

Abstract: Certain aspects of the present disclosure provide methods and apparatus for current-limiting protection of an amplifier, such as a power amplifier in a radio frequency (RF) front-end. One example current-limiting circuit generally includes a node coupled to a current source, a plurality of current-sinking devices coupled to the node, one or more switches coupled between the node and at least one of the plurality of current-sinking devices, and a bias circuit having an input coupled to the node and an output for coupling to an input of the amplifier.

Abstract: A circuit including a radio frequency (RF) amplifier including a transistor configured to receive an RF signal at its control terminal, a capacitor coupled to a first terminal of the transistor, an inductor coupled to a second terminal of the transistor, wherein the capacitor and inductor form a loop from the first terminal to the second terminal, wherein the loop bypasses a parasitic inductance between the second terminal and ground.