Method and apparatus for high efficiency power amplification
First Claim
1. A power amplifier circuit comprising:
- a carrier amplifier having a carrier signal input, a carrier signal output, and a bias input, wherein said carrier signal input is coupled to an input of said power amplifier circuit and said carrier signal output is coupled to an output of said power amplifier circuit;
an envelope detector coupled to said input of said power amplifier circuit, wherein said envelope detector produces an envelope signal; and
an envelope amplifier having a signal input responsive to said envelope signal, an output coupled to said bias input, a control input driven by a control signal, which causes said envelope amplifier to operate in one of two states, wherein when said control signal is in a first state, said envelope amplifier operates in an on state, said envelope signal is amplified by said envelope amplifier, and said bias input is driven by an amplified replica of said envelope signal, and when said control signal is in a second state, said envelope amplifier operates in an off state, said envelope amplifier produces a fixed bias which is independent of said envelope signal, and said bias input is driven by said fixed bias.
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Abstract
A method and apparatus for efficient power amplification over a wide dynamic range and for a number of modulation formats includes a carrier amplifier (30) and a peaking amplifier (40). The carrier amplifier (30) operates with a bias generated by an envelope amplifier (80) which amplifies the envelope of an input signal as generated by an envelope detector (70). The peaking amplifier (40) operates with a fixed bias. The outputs of the carrier amplifier (30) and the peaking amplifier (40) are combined using an impedance transforming network (50). Envelope amplifier (80) can be turned on for high efficiency low power level operation, or it can be turned off for standard Doherty-type operation.
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Citations
20 Claims
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1. A power amplifier circuit comprising:
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a carrier amplifier having a carrier signal input, a carrier signal output, and a bias input, wherein said carrier signal input is coupled to an input of said power amplifier circuit and said carrier signal output is coupled to an output of said power amplifier circuit; an envelope detector coupled to said input of said power amplifier circuit, wherein said envelope detector produces an envelope signal; and an envelope amplifier having a signal input responsive to said envelope signal, an output coupled to said bias input, a control input driven by a control signal, which causes said envelope amplifier to operate in one of two states, wherein when said control signal is in a first state, said envelope amplifier operates in an on state, said envelope signal is amplified by said envelope amplifier, and said bias input is driven by an amplified replica of said envelope signal, and when said control signal is in a second state, said envelope amplifier operates in an off state, said envelope amplifier produces a fixed bias which is independent of said envelope signal, and said bias input is driven by said fixed bias. - View Dependent Claims (2, 3, 4, 5)
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6. A power amplifier circuit comprising:
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a carrier amplifier having a carrier signal input, a bias input, and an output, wherein said carrier signal input is coupled to an input of said power amplifier circuit, and said output of said carrier amplifier is coupled to an output of said power amplifier circuit; an envelope detector coupled to said input of said power amplifier circuit for producing an envelope signal; an envelope amplifier having an input responsive to said envelop signal, an output coupled to said bias input, a control input driven by a control signal, which causes said envelope amplifier to operate in one of two states, wherein when said control signal is in a first state, said envelope amplifier operates in an on state, said envelope signal is amplified by said envelope amplifier, and said bias input is driven by an amplified replica of said envelope signal, and when said control signal is in a second state, said envelope amplifier operates in an off state, said envelope amplifier produces a fixed bias which is independent of said envelope signal, and said bias input is driven by said fixed bias; and a peaking amplifier having an input coupled to said input of said power amplifier circuit, and an output coupled to said output of said power amplifier circuit. - View Dependent Claims (7, 8, 9, 10)
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11. A communications device including a power amplifier circuit wherein said power amplifier circuit comprises:
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a carrier amplifier having a carrier signal input, a bias input, and an output, wherein said carrier signal input is coupled to an input of said power amplifier circuit, and said output of said carrier amplifier is coupled to an output of said power amplifier circuit; an envelope detector coupled to said input of said power amplifier circuit for producing an envelope signal; an envelope amplifier having an input responsive to said envelope signal, an output coupled to said bias input, a control input driven by a control signal, which causes said envelope amplifier to operate in one of two states, wherein when said control signal is in a first state, said envelope amplifier operates in an on state, said envelope signal is amplified by said envelope amplifier, and said bias input is driven by an amplified replica of said envelope signal, and when said control signal is in a second state, said envelope amplifier operates in an off state, said envelope amplifier produces a fixed bias which is independent of said envelope signal, and said bias input is driven by said fixed bias; and a peaking amplifier having an input coupled to said input of said power amplifier circuit, and an output coupled to said output of said power amplifier circuit. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method of modulating a carrier amplifier, said method comprising the steps of:
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envelope detecting an input signal to produce an envelope signal; determining from a control signal when a time varying amplitude is required; amplifying said envelope signal to produce a bias signal when said control signal is in a first state; producing a fixed bias for said bias signal when said control signal is in a second state; and modulating said carrier amplifier with said bias signal. - View Dependent Claims (19, 20)
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Specification