Apparatus and method for controlling power amplifier

A control device for controlling a power amplifier configured to amplify a radio frequency (RF) signal, the device comprising:

• a detector encoder configured to receive an analog detection signal from a detector and to translate the detection signal into a plurality of digital detection signals, the analog detection signal indicating a power level of the RF signal;
• a switch sequencer configured to translate the plurality of digital detection signals from the detector encoder into a plurality of input signals in a predetermined sequence;
• and
• a power switch configured to provide an output voltage to the power amplifier in response to the plurality of input signals received from the switch sequencer, the output voltage having a first value corresponding to a supply voltage from a supply voltage source when the power level of the RF signal is below a predetermined power threshold, and having a second value corresponding to the supply voltage plus a voltage boost when the power level of the RF signal is above the power threshold, wherein the second value of the output voltage enables the power amplifier to operate above saturation voltage when the power level is above the power threshold.

A method of selectively boosting a drain supply voltage of an output transistor in a power amplifier amplifying a radio frequency (RF) signal, the method comprising:

• evaluating magnitude of an envelope of the RF signal and detecting a lowest occurring voltage extreme of the envelope;
• outputting an analog detection signal indicating the detected lowest occurring voltage extreme;
• translating the analog detection signal into a plurality of digital detection signals;
• providing a supply voltage as the drain supply voltage by turning on a switching transistor to directly connect a supply voltage source to the output transistor, and connecting a charge storage capacitor between the supply voltage source and ground to charge the capacitor to a voltage boost value, in response to the digital detection signals, when the detected lowest occurring voltage extreme is greater than a predetermined voltage level;
• and
• providing a boosted voltage as the drain supply voltage by turning off the switching transistor and connecting the charge storage capacitor between the supply voltage source and the output transistor, in response to the digital detection signals, when the detected lowest occurring voltage extreme becomes less than the predetermined voltage level, the boosted voltage comprising the supply voltage plus the voltage boost value previously stored in the charge storage capacitor.