Method and apparatus for protecting devices in an RF power amplifier
First Claim
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1. A circuit for protecting devices in an RF power amplifier comprising:
- a peak detector coupled to an output of the power amplifier for detecting peak voltages at the output of the power amplifier, wherein the peak detector further comprises;
a first peak detector having an input coupled to the output of the power amplifier;
a second peak detector having an input coupled to a reference tone; and
control circuitry coupled to the peak detector and to the power amplifier for controlling the gain of the power amplifier, wherein the control circuitry decreases the gain of the power amplifier when the peak detector detects a voltage above a voltage threshold.
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Abstract
A method and apparatus are provided for use with a power amplifier for protecting active devices on the power amplifier. A peak detector is used by control circuitry to detect the presence of a peak voltage that exceeds a threshold voltage. In response to the detection of a peak voltage, the gain of the power amplifier is reduced.
110 Citations
19 Claims
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1. A circuit for protecting devices in an RF power amplifier comprising:
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a peak detector coupled to an output of the power amplifier for detecting peak voltages at the output of the power amplifier, wherein the peak detector further comprises;
a first peak detector having an input coupled to the output of the power amplifier;
a second peak detector having an input coupled to a reference tone; and
control circuitry coupled to the peak detector and to the power amplifier for controlling the gain of the power amplifier, wherein the control circuitry decreases the gain of the power amplifier when the peak detector detects a voltage above a voltage threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit comprising:
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an RF power amplifier having an input and an output;
a peak detector coupled to the power amplifier for detecting a peak voltage at a node of the power amplifier, wherein the peak detector is comprised of first and second peak detectors; and
power control circuitry coupled to the peak detector and to the power amplifier for controlling the gain of the power amplifier, wherein the power control circuitry limits the power at the output of the power amplifier when the peak detector detects a peak voltage greater than a threshold voltage. - View Dependent Claims (9, 10, 11)
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12. A method of protecting devices in an RF power amplifier comprising the steps of:
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detecting a peak voltage at a first node of the power amplifier, wherein the peak voltage is detected using the steps of;
providing a first peak detector coupled to the output of the power amplifier; and
providing a second peak detector coupled to a reference tone;
determining whether the detected peak voltage is higher than a threshold voltage; and
if it is determined that the detected peak voltage is higher than the threshold voltage, decreasing the gain of the power amplifier. - View Dependent Claims (13, 14, 15, 16)
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17. A method of controlling an RF power amplifier comprising the steps of:
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detecting the output power of the RF power amplifier;
detecting a peak voltage at a first node of the power amplifier, wherein the step of detecting a peak voltage further comprises the steps of;
providing a first peak detector coupled to the power amplifier;
providing a second peak detector coupled to a reference tone; and
combining the outputs of the first and second peak detectors;
increasing the gain of the power amplifier if the detected output power is less than a desired output power level and if the detected peak voltage does not exceed a threshold voltage; and
decreasing the gain of the power amplifier if the detected output power is greater than the desired output power level or if the detected peak voltage exceeds a threshold voltage. - View Dependent Claims (18, 19)
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Specification