Method and apparatus for optimum biasing of cascaded MOSFET radio-frequency devices
First Claim
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1. A cascaded multi-stage power amplifier, comprising:
- a first stage amplifier biased to operate in a region of gain expansion; and
a second stage amplifier coupled to the first stage amplifier and biased to operate in a region of gain compression, the second stage including a plurality of amplifiers in a parallel configuration, the plurality of amplifiers being biased at different operating points selected to reduce adjacent band power.
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Abstract
Generally, the invention relates to a method and apparatus to improve the performance of multi-stage radio frequency linear power amplifiers. More particularly, the present invention discloses a cascaded gain expansion stage and gain compression stage at differing bias levels to produce an amplifier with superior linearity and lower intermodulation distortion and adjacent channel power than any single stage by alone.
30 Citations
21 Claims
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1. A cascaded multi-stage power amplifier, comprising:
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a first stage amplifier biased to operate in a region of gain expansion; and
a second stage amplifier coupled to the first stage amplifier and biased to operate in a region of gain compression, the second stage including a plurality of amplifiers in a parallel configuration, the plurality of amplifiers being biased at different operating points selected to reduce adjacent band power. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method to minimize intermodulation distortion and reduce adjacent band power of a multi-stage power amplifier, comprising:
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biasing a first stage amplifier to operate in a region of gain expansion; and
biasing a second stage amplifier, which is coupled to the first stage amplifier, to operate in a region of gain compression, the second stage amplifier having a plurality of amplifiers in a parallel configuration, the biasing including biasing the plurality of amplifiers of the second stage at different operating points selected to reduce adjacent band power. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
adaptively biasing the first stage amplifier as the output of the power amplifier is varied.
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18. A cascaded multi-stage power amplifier, comprising:
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a first stage amplifier; and
a second stage amplifier coupled to an output of the first stage amplifier, the second stage including a plurality of amplifiers in a parallel configuration, the plurality of amplifiers being biased at different operating points selected to reduce adjacent band power.
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19. A cascaded multi-stage power amplifier, comprising:
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an RF base station amplifier having;
a first stage amplifier; and
a second stage amplifier coupled to an output of the first stage amplifier, the second stage including a plurality of amplifiers in a parallel configuration, the plurality of amplifiers being biased at different operating points selected to reduce adjacent band power.
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20. A method of reducing adjacent band power output of a cascaded multi-stage power amplifier comprising:
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providing an output stage for the power amplifier having a plurality of amplifiers coupled in parallel; and
,biasing the plurality of amplifiers at different operating points selected to reduce adjacent band power.
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21. A method of reducing adjacent band power output of a cascaded multi-stage RF base station power amplifier comprising:
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providing an output stage for the RF base station power amplifier having a plurality of amplifiers coupled in parallel; and
,biasing the plurality of amplifiers at different operating points selected to reduce adjacent band power.
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Specification