Apparatus and method for controlling power amplifier
First Claim
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, andwherein;
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.
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Abstract
An apparatus for controlling a power amplifier configured to amplify radio frequency (RF) signal includes a detector and a controller. The detector is configured to detect a power level of the RF signal with respect to a predetermined power threshold and to generate a corresponding detection signal. The controller is configured to provide a control voltage to an output transistor of the amplifier based on the detection signal. 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 has a high voltage value when the detection signal indicates that the power level is above the power threshold. The controller generates the high voltage value by boosting the supply voltage.
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Citations
18 Claims
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1. An apparatus for controlling operation of a power amplifier configured to amplify a radio frequency (RF) signal, the apparatus comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A control device for controlling a power amplifier configured to amplify a radio frequency (RF) signal, the device comprising:
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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. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. 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:
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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.
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Specification