Application of the doherty amplifier as a predistortion circuit for linearizing microwave amplifiers
First Claim
1. A predistortion driver circuit for a serially connected downstream Doherty power amplifier having predetermined characteristics, the predistortion driver circuit comprising:
- a Doherty driver amplifier having a carrier amplifier and a peak amplifier, each of said carrier and peak amplifiers having a respective bias level, the bias levels for said Doherty driver amplifier selected to provide for predistortion of predetermined characteristics of said serially connected downstream Doherty power amplifier, wherein said predetermined characteristics selected to provide gain expansion as a function of input power level.
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Accused Products
Abstract
A predistortion circuit for a microwave amplifier and more particularly to predistortion circuit configured as a Doherty amplifier. The predistortion circuit is adapted to be coupled to a downstream Doherty amplifier to precompensate for the gain compression and phase expansion of the downstream Doherty amplifier as the input power level is increased while simultaneously reducing the intermodulation (IM) distortion. In order to provide precompensation, the precompensation circuit is operated at bias level to provide gain expansion and phase compression to cancel out the gain compression and phase expansion of the downstream Doherty amplifier to provide a higher overall linear power added efficiency (PAE).
146 Citations
11 Claims
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1. A predistortion driver circuit for a serially connected downstream Doherty power amplifier having predetermined characteristics, the predistortion driver circuit comprising:
a Doherty driver amplifier having a carrier amplifier and a peak amplifier, each of said carrier and peak amplifiers having a respective bias level, the bias levels for said Doherty driver amplifier selected to provide for predistortion of predetermined characteristics of said serially connected downstream Doherty power amplifier, wherein said predetermined characteristics selected to provide gain expansion as a function of input power level.
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2. A predistortion driver circuit for a Doherty power amplifier having predetermined characteristics, the predistortion driver circuit comprising:
a Doherty driver amplifier having a carrier amplifier and a peak amplifier, each of said peak and carrier amplifiers having a respective bias level, the bias levels for said Doherty driver amplifier selected to provide for predistortion of predetermined characteristics of the bias levels of said Doherty power amplifier, wherein the bias levels are selected to provide phase compression as a function of input power level, wherein said predetermined characteristics include gain as a function of input power level and phase and wherein said bias levels are selected to provide gain expansion as a function of input power level.
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3. A linear power amplifier circuit comprising:
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a Doherty power amplifier having predetermined characteristics including input power range as a function of RF input power; and
an upstream predistortion driver circuit configured as a Doherty amplifier, serially coupled to said Doherty power amplifier, said upstream predistortion driver circuit having characteristics selected to precompensate for said predetermined characteristics of said power amplifier as a function of input power, wherein said predetermined characteristic include gain as a function of input power level and phase and wherein said bias level is selected to provide gain expansion as a function of input power level. - View Dependent Claims (4, 5)
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6. A linear power amplifier circuit comprising:
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a Doherty power amplifier having predetermined characteristics including input power range as a function of RF input power; and
an upstream predistortion driver circuit configured as a Doherty amplifier, serially coupled to said Doherty power amplifier, said predistortion circuit having characteristics selected to precompensate for said predetermined characteristics of said power amplifier as a function of input power, wherein said Doherty power amplifier having a predetermined phase compression characteristic as a function of input power, wherein said predetermined characteristics include gain as a function of input power level and phase and wherein said bias levels are selected to provide gain expansion as a function of input power level. - View Dependent Claims (7)
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8. A linear power amplifier circuit comprising:
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a Doherty power amplifier having predetermined characteristics including an input power range as a function of RF input power;
an upstream predistortion driver circuit configured as at Doherty driver amplifier for precompensating said predetermined characteristics of said Doherty power amplifier; and
a circuit for electronically tuning said upstream predistortion circuit so that a predetermined characteristic of the linear power amplifier circuit is linear over the input power range of the Doherty power amplifier, said electronic tuning circuit configured to adjust the bias characteristic of said upstream predistortion circuit, wherein said predetermined characteristics include gain as a function of input power level mid phase and wherein said bias levels of said Doherty driver amplifier are selected to provide gain expansion as a function of input power level. - View Dependent Claims (9)
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10. A linear power amplifier circuit comprising:
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a Doherty power amplifier having predetermined characteristics including an input power range as a function of RF input power;
an upstream predistortion circuit configured as a Doherty driver amplifier for precompensating said predetermined characteristics of said Doherty power amplifier; and
a circuit for electronically tuning said upstream predistortion circuit so that a predetermined characteristic of the linear power amplifier circuit is linear over the input power range of the Doherty power amplifier, wherein said power amplifier is configured as a Doherty amplifier having a predetermined phase compression characteristic as a function of input power, wherein said predetermined characteristics further include gain as a function of input power level and wherein said bias levels are selected to provide gain expansion as a function of input power level. - View Dependent Claims (11)
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Specification