AMPLIFIER WITH POWER DISSIPATION REDUCTION USING SINGLE RADIO FREQUENCY DIGITAL-TO-ANALOG CONVERTER
First Claim
1. A method, comprising:
- receiving a combined digital signal at a digital-to-analog converter (DAC), the combined digital signal including at least a digital amplifier bias control signal and a digital data signal;
producing, by the DAC, from the combined digital signal a combined analog RF signal comprising an analog radio frequency (RF) data signal in a first frequency band and an analog RF amplifier bias control signal in a second frequency band, wherein the first frequency band is a higher frequency band than the second frequency band and the first and second frequency bands are mutually exclusive;
outputting the combined analog RF signal to a filter; and
filtering, by the filter, the combined analog RF signal to output the analog RF data signal, the RF data signal being configured to be applied to a signal input terminal of an RF amplifier and to output the analog RF amplifier bias control signal, the analog RF amplifier bias control signal being configured to be applied to a bias control input terminal of the RF amplifier.
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Accused Products
Abstract
The disclosed system and method provide for a CATV power amplifier in which power dissipation may be reduced by dynamically adjusting the amplifier bias such that the bias is high only when high peak output signals need to be produced. By combining a bias control signal and an RF data signal into a single signal produced by a single DA converter, the disclosed examples require fewer DA converters and a need to synchronize DA converters to produce each of the signals individually is eliminated. A low frequency signal may be added to the RF band to find an optimum compromise between positive and negative peak excursions produced by the amplifier such that an overall reduction in bias may be achieved.
11 Citations
22 Claims
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1. A method, comprising:
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receiving a combined digital signal at a digital-to-analog converter (DAC), the combined digital signal including at least a digital amplifier bias control signal and a digital data signal; producing, by the DAC, from the combined digital signal a combined analog RF signal comprising an analog radio frequency (RF) data signal in a first frequency band and an analog RF amplifier bias control signal in a second frequency band, wherein the first frequency band is a higher frequency band than the second frequency band and the first and second frequency bands are mutually exclusive; outputting the combined analog RF signal to a filter; and filtering, by the filter, the combined analog RF signal to output the analog RF data signal, the RF data signal being configured to be applied to a signal input terminal of an RF amplifier and to output the analog RF amplifier bias control signal, the analog RF amplifier bias control signal being configured to be applied to a bias control input terminal of the RF amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A cable television system node, comprising:
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a pre-amplifier stage including at least one filter, the pre-amplifier stage configured to; receive a combined signal including a radio frequency (RF) data signal and an RF bias control signal, filter the combined signal to separate the RF data signal from the RF bias control signal; and amplify the RF data signal to produce an amplified RF data signal; and a plurality of power amplifiers coupled to the preamplifier stage, each of the power amplifiers configured to receive the amplified RF data signal at a signal input terminal and the RF bias control signal at a bias input terminal, wherein each of the power amplifiers is configured to; in response to the bias control signal being applied to a bias control input of the power amplifier, dynamically adjust an overall bias of the power amplifier while amplifying the received RF data signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An amplification system, comprising:
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a digital to analog converter, the digital to analog converter coupled to; receive a combined digital signal from the digital data processing stage, the combined digital signal including a digital data signal and a digital amplifier bias control signal, and output a combined radio frequency (RF) signal that is an analog representation of the combined digital signal; and a filter stage coupled to the digital to analog converter, the filter stage configured to; filter the combined RF signal to separate an analog RF data signal and an analog amplifier bias control signal from the analog combined RF signal. - View Dependent Claims (18, 19, 20, 21)
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22. A method, comprising:
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receiving a combined digital signal at a digital-to-analog converter (DAC), the combined digital signal including at least a digital amplifier bias control signal and a digital data signal; producing by the DAC a modified combined analog RF signal comprising in addition to the analog RF data signal in the first frequency band and the analog RF amplifier bias control signal in the second frequency band, an analog low frequency data peak reduction signal in the second frequency band of the modified, combined RF signal; combining the analog low frequency data peak reduction signal in the second frequency band with the filtered analog RF data signal in the first frequency band, wherein the low frequency data peak reduction signal in the second frequency band with the filtered analog RF data signal in the first frequency band are configured to, when applied to the signal input terminal of an RF amplifier, reduce peak excursions of the overall data signal provided by the RF amplifier; and outputting the combined analog RF signal to a filter.
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Specification