High linearity multicarrier RF amplifier
First Claim
1. A RF power amplifier arrangement comprising:
- an RF input port to which an RF input signal is applied;
an RF output port from which an RF output signal is derived;
an RF carrier cancellation loop coupled between said RF input port and said RF output port and including an RF amplifier stage that is operative to provide a first amplified RF output, said RF amplifying stage including first and second RF signal processing paths containing first and second matched RF power amplifiers coupled in circuit with one another in such a manner that said second matched amplifier is pre-distorted by the output of said first matched amplifier which is driven by essentially the same RF signals driving said second matched amplifier, said first and second RF signal processing paths being differentially combined to produce a composite RF output in which RF carrier components constructively combine and distortion introduced by said matched RF power amplifiers destructively combine;
a feed-forward amplifier loop coupled to said RF carrier cancellation loop and being operative to provide a second amplified RF output containing distortion introduced by said RF amplifier stage but effectively excluding said RF input signal; and
an output signal combiner coupled to receive said first and second amplified RF outputs of said RF carrier cancellation loop and said feed-forward amplifier loop, respectively, and being operative to produce a composite RF output signal, in which distortion introduced by said RF amplifier stage is reduced.
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Abstract
A hybrid multicarrier RF power amplifier linearization architecture combines ACT and feed-forward amplifier stages to achieve high output distortion rejection and enhanced amplifier linearity. A carrier cancellation loop is coupled with a main RF power amplifier stage having parallel RF power amplifiers coupled via intermod-complementing predistortion paths. The carrier cancellation loop is coupled to a feed-forward loop containing a feed-forward RF power amplifier, to produce a composite amplified output signal having very reduced intermodulation products. Vector modulators in the main amplifier and feed-forward amplifier stages are controlled by a digital signal processor, using outputs from various monitoring subsystems, including pilot tone detection, correlator, distortion and power detector circuits.
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Citations
20 Claims
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1. A RF power amplifier arrangement comprising:
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an RF input port to which an RF input signal is applied;
an RF output port from which an RF output signal is derived;
an RF carrier cancellation loop coupled between said RF input port and said RF output port and including an RF amplifier stage that is operative to provide a first amplified RF output, said RF amplifying stage including first and second RF signal processing paths containing first and second matched RF power amplifiers coupled in circuit with one another in such a manner that said second matched amplifier is pre-distorted by the output of said first matched amplifier which is driven by essentially the same RF signals driving said second matched amplifier, said first and second RF signal processing paths being differentially combined to produce a composite RF output in which RF carrier components constructively combine and distortion introduced by said matched RF power amplifiers destructively combine;
a feed-forward amplifier loop coupled to said RF carrier cancellation loop and being operative to provide a second amplified RF output containing distortion introduced by said RF amplifier stage but effectively excluding said RF input signal; and
an output signal combiner coupled to receive said first and second amplified RF outputs of said RF carrier cancellation loop and said feed-forward amplifier loop, respectively, and being operative to produce a composite RF output signal, in which distortion introduced by said RF amplifier stage is reduced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A multicarrier RF power amplifier comprising:
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an RF input port adapted to receive a multicarrier RF input signal;
an RF output port from which an amplified multicarrier RF output signal is derived;
an RF amplifier stage coupled in circuit with a first vector modulator to said RF input port and being operative to provide a first amplified multicarrier RF output, said RF amplifying stage including first and second RF signal processing paths containing first and second matched RF power amplifiers that are coupled in circuit with one another in such a manner that said second matched amplifier is pre-distorted by the output of said first matched amplifier which is driven by essentially the same RF signals driving said second matched amplifier, said first and second RF signal processing paths being differentially combined to produce a composite amplified multicarrier RF output in which RF carrier components of said multicarrier RF input signal constructively combine and distortion introduced by said first and second matched RF power amplifiers destructively combine;
an RF carrier cancellation loop coupled to said RF input port and to said RF amplifier stage and being operative to extract distortion energy imparted to said first amplified multicarrier RF output by said RF amplifier stage;
a feed-forward amplifier loop coupled to said RF carrier cancellation loop and including a feed-forward RF amplifier stage coupled in circuit with a second vector modulator, and being operative to provide a second amplified RF output containing distortion introduced by said RF amplifier stage but effectively excluding said multicarrier RF input signal; and
an output signal combiner coupled to receive outputs of said RF carrier cancellation loop and said feed-forward amplifier loop, and being operative to produce a composite multicarrier RF output signal, in which distortion introduced by said RF amplifier stage is effectively reduced. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification