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 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 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: 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.