| 1. |
- Landin, Per, 1983-, et al.
(författare)
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Overview of Synergetic OFDM Crest Factor Reduction and Digital Pre-Distortion for RF PAs
- 2011
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Ingår i: RFMTC11.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Digital baseband pre-distortion (DPD) is used to linearize nonlinear RF PAs, crest factor reduction (CFR) to increase the maximum output power level of RF PAs. Together they result in increased output power with maintained, or even, better linearity. This paper discuss some of the techniques for DPD and CFR methods currently under investigation. Measured results for a class-AB PA using OFDM signals indicate a possibility to increase the power added efficiency (PAE) by at least 15%-points, from 30% to 45%, and a power output increase of 6 dB while maintaining specified ACLR requirements.
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| 2. |
- Landin, Per, 1983-, et al.
(författare)
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Proofs of Derivations in Memory Polynomial Baseband Modeling of RF Power Amplifiers
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper contains supporting derivations for the paperMemory Polynomial Baseband Modeling of RF Power Am-plifiers. All references to numbered equations, propositionsand assumptions are to the corresponding number inMemoryPolynomial Baseband Modeling of RF Power Amplifiers.
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| 3. |
- Nader, Charles, 1982-, et al.
(författare)
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Characterizing the out-of-band Nonlinear Behavior of RF Devices : The Key to Success
- 2011
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Ingår i: Conference Record - IEEE Instrumentation and Measurement Technology Conference. - New York : IEEE. - 9781424479337 - 9781424479351 ; , s. 790-794
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Konferensbidrag (refereegranskat)abstract
- This paper presents a measurement recipe to characterize the out-of-band nonlinear behavior of RF devices when harmonic sampling is used as a digitizing technique. A major challenge to consider when using harmonic sampling is the overlapping of the aliased spectral bins of the digitized waveform. This challenge is more pronounced when using modulated excitation signals. In addition, the excitation signal used should mimic the real behavior of signals used in today's wireless systems. Hence, this paper provides the reader with a tool to select the proper excitation signal, sampling frequency and record length in order to achieve an accurate characterization of the nonlinear behavior of RF devices.
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| 4. |
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| 5. |
- Nader, Charles, et al.
(författare)
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Harmonic Sampling and Reconstruction of Wideband Undersampled Waveforms : Breaking the Code
- 2011
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Ingår i: IEEE transactions on microwave theory and techniques. - : IEEE. - 0018-9480 .- 1557-9670. ; 59:11, s. 2961-2969
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a method for measuring wideband waveforms correctly when undersampling is used as a digitizing technique is presented. Two major challenges arise when undersampling wideband waveforms: overlapping of aliased spectral bins of the digitized waveform and ambiguity in spectral bins standing on multiples of the Nyquist frequency. Those challenges are more pronounced when using wideband modulated signals to excite nonlinear devices. The theory behind a correct undersampled measurement is based on the use of an irrational relation between the undersampling frequency and the spectral resolution of the waveform to measure. This is the key to a successful harmonic sampling used today in large-signal network analyzers when wideband modulated waveforms are to be measured. Inverting the problem, such theory is also the solution for reconstructing wideband undersampled waveforms based on a single measurement and with a relatively short record of measured data. It is a solution for RF sampling and cognative radios where the digital processing is moving toward the antenna of the receiver.
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| 6. |
- Nader, Charles, 1982-, et al.
(författare)
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Peak-to-average power ratio reduction versus digital pre-distortion in OFDM based systems
- 2011
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Ingår i: Microwave Symposium Digest (MTT), 2011 IEEE MTT-S International. - : IEEE. - 9781612847566 ; , s. 1-4
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Konferensbidrag (refereegranskat)abstract
- In this paper we evaluate the effect of applying peak-to-average power ratio (PAPR) reduction and digital pre-distortion (DPD) on radio frequency power amplifiers when an orthogonal frequency division multiplexing (OFDM) signal is used. The PAPR reduction method, presented as a convex problem, is based on reshaping the time domain signal by redistributing its energy in the frequency domain, with respect to constraints on in-band and out-of-band errors. The DPD method consists of modeling the behavior of the power amplifier using a parallel Hammerstein model, and then extracting its inverse parameters based on the indirect learning approach. The cases where PAPR and DPD are applied separately and combined, are studied and investigated. Power amplifier figures of merit are evaluated. A good performance is shown when combining both pre-processing techniques up to a certain operating point where DPD performance deteriorates. Solutions to improve the DPD performance at strong compression are suggested.
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| 7. |
- Nader, Charles, 1982-, et al.
(författare)
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Performance Evaluation of Peak-to-Average Power Ratio Reduction and Digital Pre-Distortion for OFDM Based Systems
- 2011
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Ingår i: IEEE transactions on microwave theory and techniques. - 0018-9480 .- 1557-9670. ; 59:12, s. 3504-3511
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we evaluate the effect of applying peak-to-average power ratio (PAPR) reduction and digital pre-distortion (DPD) on two types of radio frequency power amplifiers when an orthogonal frequency division multiplexing (OFDM) signal is used. The power amplifiers under test are a standard class-AB amplifier and a Doherty amplifier. The PAPR reduction methods are based on a state-of-the art convex optimization formulation and on the standard clipping and filtering technique. The DPD method consists of modeling the behavior of the power amplifier using a parallel Hammerstein model, and then extracting the inverse parameters based on the indirect learning architecture. To achieve better DPD performance, extracting the DPD parameters based on multiple-step iterations is investigated. The cases where PAPR reduction and DPD are applied separately and combined are studied and investigated. Power amplifier figures of merit are evaluated. Good performance is shown when combining both pre-processing techniques up to a certain operating point where DPD performance deteriorates due to generation of strong peaks in the signal. In addition, a difference in the power amplifier behavior is reported and analyzed.
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| 8. |
- Voet, Kevin, et al.
(författare)
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Mirrored parallel Hammerstein predistortion for multitone generation
- 2011
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Ingår i: 2011 IEEE INTERNATIONAL INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE (I2MTC). - 9781424479351 - 9781424479337 ; , s. 814-817
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Konferensbidrag (refereegranskat)abstract
- The paper discusses the approach tested for digital pre-distortion of radio frequency vector signal generators, where joint mitigation of impairments is considered stemming from the inphase/quadrature modulator, local oscillator, and power amplifier. A predistorter structure, linear in its parameters, was taken and the parameters were estimated by the least-squares method. The proposed method is validated by demonstrating improvement in the performance of the Rohde & Schwarz SMU200 by about 8 dB reduction in mirror-frequency interference, 17 dB reduction in leakage from the local oscillator, and 6 dB improvement in inter-modulation products. Thus, the tested approach is considered useful for several instrumentation and measurement applications.
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| 9. |
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