Power amplifier with improved low bias mode linearity

摘要

Power amplifier circuitry includes a power amplifier including an input node and an output node, biasing circuitry, a selectable impedance network, and an input capacitor. The input capacitor is coupled to the input node of the power amplifier. The biasing circuitry is coupled to the input node of the power amplifier through the selectable impedance network. The power amplifier is operable in a low power operating mode and a high power operating mode. In the low power operating mode, the biasing circuitry delivers a first biasing current to the input node of the power amplifier, and a first impedance level of the selectable impedance is selected. In the high power operating mode, the biasing circuitry delivers a second biasing current to the input node of the power amplifier, and a second impedance level of the selectable impedance is selected.

主权项

1. Circuitry comprising:
a power amplifier including an input node and an output node; an input capacitor coupled to the input node of the power amplifier, such that the power amplifier is configured to receive an RF input signal via the input capacitor; a selectable impedance network comprising:
a first selectable impedance node;a second selectable impedance node coupled to the input node of the power amplifier;an impedance element coupled between the first selectable impedance node and the second selectable impedance node;a switching element coupled in parallel with the impedance element between the first selectable impedance node and the second selectable impedance node; and biasing circuitry coupled to the first selectable impedance node of the selectable impedance network, wherein:
the circuitry is configured to operate in a low power operating mode in which the biasing circuitry supplies a first biasing current to the input node of the power amplifier through the impedance element in the selectable impedance network; andthe circuitry is configured to operate in a high power operating mode in which the biasing circuitry supplies a second biasing current to the input node of the power amplifier at least partially through the switching element in the selectable impedance network.