Patent ID: 8174313
Filing Date: 2012-05-08
Classification: H03F,H03G

Abstract:
1. An apparatus for controlling operation of a power amplifier configured to amplify a radio frequency (RF) signal, the apparatus comprising: a detector configured to detect a power level of the RF signal with respect to a predetermined power threshold and to generate a corresponding analog detection signal indicating the power level of the RF signal; and a controller comprising a detector encoder, configured to translate the analog detection signal into a plurality of digital detection signals, and a power switch comprising a switching transistor and a charge storage capacitor, the controller providing a control voltage to an output transistor of the amplifier based on the plurality of digital detection signals, wherein the control voltage has a low voltage value, which is substantially the same as a value of a supply voltage, when the detection signal indicates that the power level is below the power threshold, and the control voltage having a high voltage value when the detection signal indicates that the power level is above the power threshold, the high voltage value being about twice the low voltage value, wherein the controller generates the high voltage value by boosting the supply voltage, and wherein: when the detection signal indicates that the power level is below the power threshold, the switching transistor is turned on to pass the supply voltage to an output of the power switch, and the charge storage capacitor is connected between the supply voltage and ground to charge the charge storage capacitor to a capacitor voltage that is about equal to the supply voltage, so that the control voltage has the supply voltage value; and when the detection signal indicates that the power level is above the power threshold, the switching transistor is turned off to disconnect the supply voltage from the output of the power switch, and the charge storage capacitor is connected between the supply voltage and the output of the power switch, so that the control voltage has a sum of the capacitor voltage and the supply voltage.