A power amplifier (PA) system includes an amplifying transistor having a base, a collector, and an emitter. The PA system further includes a radio-frequency (RF) input configured to receive an RF input signal having an RF component and a DC bias component, a bias circuit coupled to the base of the amplifying transistor, and a bias tee circuit configured to receive the RF input signal and pass at least a portion of the DC component to the bias circuit and at least a portion of the RF component to the base of the amplifying transistor.

Methods and apparatus are provided. In an example aspect, a method of operating an amplifier circuit is provided. The amplifier circuit comprises a first amplifier configured to receive a first signal, a balanced amplifier comprising second and third amplifiers and configured to receive a second signal, and a first directional coupler. An output of the first amplifier is connected to a transmitted port of the first directional coupler, an output of the second amplifier is connected to an input port of the first directional coupler, an output of the third amplifier is connected to an isolated port of the first directional coupler, and a coupled port of the first directional coupler is connected to an output of the amplifier circuit. The method comprises operating the amplifier circuit in a first output peak amplitude range of the amplifier circuit wherein, in the first output peak amplitude range, the first signal is based on a signal to be amplified and has an amplitude that increases across the first output peak amplitude range from substantially zero to a first amplitude, and the second signal is substantially zero, and operating the amplifier circuit in a second output peak amplitude range of the amplifier circuit, wherein the second output peak amplitude range is higher than the first output peak amplitude range and wherein, in the second output peak amplitude range, the first signal is based on the signal to be amplified and has an amplitude that decreases across the second output peak amplitude range from the first amplitude to a second amplitude, and the second signal is based on the signal to be amplified and has an amplitude that increases across the second output peak amplitude range from a third amplitude to a fourth amplitude.