Power amplifier saturation detection
First Claim
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1. A power amplifier system comprising:
- a first integrated circuit chip, the first integrated circuit chip including a power amplifier and a limiter in electrical communication with the power amplifier, the limiter including a diode that clips a positive voltage excursion and passes a negative voltage excursion to an averaging filter; and
a second integrated circuit chip including a comparator in electrical communication with the averaging filter and configured to generate a saturation detection signal based at least in part on an output of the averaging filter, the second integrated circuit chip further including a first switch and a second switch, the first switch configured to electrically connect the output of the averaging filter to a first input of the comparator and the second switch configured to electrically connect an output of a second averaging filter to a second input of the comparator when a first band-select signal is received, the output of the second averaging filter serving as a comparator reference voltage when the first band-select signal is received.
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Abstract
In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.
33 Citations
20 Claims
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1. A power amplifier system comprising:
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a first integrated circuit chip, the first integrated circuit chip including a power amplifier and a limiter in electrical communication with the power amplifier, the limiter including a diode that clips a positive voltage excursion and passes a negative voltage excursion to an averaging filter; and a second integrated circuit chip including a comparator in electrical communication with the averaging filter and configured to generate a saturation detection signal based at least in part on an output of the averaging filter, the second integrated circuit chip further including a first switch and a second switch, the first switch configured to electrically connect the output of the averaging filter to a first input of the comparator and the second switch configured to electrically connect an output of a second averaging filter to a second input of the comparator when a first band-select signal is received, the output of the second averaging filter serving as a comparator reference voltage when the first band-select signal is received. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for detecting power amplifier saturation, the method comprising:
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receiving a first band-select signal at a power amplifier system, the power amplifier system including a first power amplifier and a second power amplifier; responsive to the first band-select signal, activating the first power amplifier and deactivating the second power amplifier; amplifying a first output signal of the first power amplifier; blocking a positive voltage excursion of the first output signal and passing a negative voltage excursion of the first output signal to obtain a first limited signal; averaging the first limited signal to obtain a first averaged signal; and comparing the first averaged signal to a first reference signal at a comparator to obtain a first saturation detection signal, the first reference signal based at least in part on a signal from the second power amplifier. - View Dependent Claims (13, 14, 15)
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16. A wireless device comprising:
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a baseband subsystem configured to generate a band-select signal; and a power amplifier system including a first integrated circuit chip and a second integrated circuit chip, the first integrated circuit chip including a power amplifier activated based on the band-select signal and a limiter in electrical communication with the power amplifier, the limiter including a diode that clips a positive voltage excursion and passes a negative voltage excursion to an averaging filter, the second integrated circuit chip including a comparator in electrical communication with the averaging filter and configured to generate a saturation detection signal based at least in part on an output of the averaging filter, the second integrated circuit chip further including a first switch and a second switch, the first switch configured to electrically connect the output of the averaging filter to a second input of the comparator and the second switch configured to electrically connect the output of the second averaging filter to a first input of the comparator when a band-select signal is received, the output of the first averaging filter serving as a comparator reference voltage when the band-select signal is received. - View Dependent Claims (17)
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18. A power amplifier system comprising:
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a first integrated circuit chip, the first integrated circuit chip including a power amplifier and a limiter in electrical communication with the power amplifier, the limiter including a diode that clips a positive voltage excursion and passes a negative voltage excursion to an averaging filter; and a second integrated circuit chip including a comparator in electrical communication with the averaging filter and configured to generate a saturation detection signal based at least in part on an output of the averaging filter, the second integrated circuit chip further including a first switch and a second switch, the first switch configured to electrically connect the output of the averaging filter to a second input of the comparator and the second switch configured to electrically connect the output of the second averaging filter to a first input of the comparator when a band-select signal is received, the output of the first averaging filter serving as a comparator reference voltage when the band-select signal is received.
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19. A method for detecting power amplifier saturation, the method comprising:
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receiving a first band-select signal at a power amplifier system, the power amplifier system including a first power amplifier and a second power amplifier; responsive to the first band-select signal, activating the first power amplifier and deactivating the second power amplifier; amplifying a first output signal of the first power amplifier; blocking a positive voltage excursion of the first output signal and passing a negative voltage excursion of the first output signal to obtain a first limited signal; averaging the first limited signal to obtain a first averaged signal; comparing the first averaged signal to a first reference signal at a comparator to obtain a first saturation detection signal; and comparing a second averaged signal to a second reference signal at the comparator to obtain a second saturation detection signal, the second reference signal based at least in part on a signal from the first power amplifier. - View Dependent Claims (20)
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Specification