Method and apparatus for operating a radio-frequency power amplifier as a variable-class linear amplifier
AssigneeMotorola, Inc.
InventorBrian Joseph Budnik
Life of this patent
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Abstract
A variable-class linear amplifier (600, 800, 900) applies a supply type of envelope modulation to an RF power amplifier operating in or near compression at highest envelope amplitudes, and transitions gradually to an envelope tracking type of operation at intermediate envelope amplitudes. The amplifier further transitions gradually to a linear class of operation with a constant supply voltage (508) at lowest envelope amplitudes.
Claims18
A method of operating a radio-frequency (RF) power amplifier as a variable-class linear amplifier, the method comprising the steps of:
- applying an envelope supply type of modulation at highest envelope amplitudes, to develop an output signal;
- transitioning gradually to an envelope tracking type of operation at intermediate envelope amplitudes;
- and
- further transitioning gradually to a linear class of operation with a constant supply voltage at lowest envelope amplitudes.
A variable-class linear radio-frequency (RF) power amplifier, comprising:
- supply modulation means for applying an envelope supply type of modulation at highest envelope amplitudes, to develop an output signal;
- envelope tracking means coupled to the supply modulation means for transitioning gradually to an envelope tracking type of operation at intermediate envelope amplitudes;
- and
- linear operation means coupled to the supply modulation means for further transitioning gradually to a linear class of operation with a constant supply voltage at lowest envelope amplitudes.
A method of operating a radio-frequency (RF) power amplifier as a variable-class linear amplifier, the method comprising the steps of:
- coupling a composite RF signal to an input of the RF power amplifier, the signal having an envelope amplitude which varies with time;
- forming a modulation waveform whose amplitude is substantially proportional to said envelope amplitude when said envelope amplitude is greater than a predetermined level, and whose amplitude transitions to a predetermined constant amplitude when said envelope amplitude is not greater than the predetermined level;
- and
- driving a supply input of the RF power amplifier with the modulation waveform, thereby operating the RF power amplifier in a mode selected from a group of modes, including an envelope supply modulation mode, an envelope tracking mode, and a linear mode, the mode determined by the envelope amplitude.
Dependencies are inferred from the claim text.