| 61. |
- 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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| 62. |
- Landin, Per, 1983-, et al.
(författare)
-
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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| 63. |
- Lundin, Henrik, et al.
(författare)
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On the Estimation of Quantizer Reconstruction Levels
- 2006
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 55:6, s. 2176-2182
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Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of estimating the optimal reconstruction levels of a fixed quantizer, such as the amplitude quantization part of an analog-to-digital converter. A probabilistic transfer function model is applied for the quantizer. Two different assumptions are made for the transfer function, and an estimator based on order statistics is applied. The estimator turns out to give better results in terms of mean square error than the commonly applied sample mean.
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| 64. |
- Medawar, Samer, et al.
(författare)
-
ADC Characterization By Dynamic Integral Nonlinearity
- 2008
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Ingår i: 13th Workshop on ADC Modelling and Testing. - 9788890314933 ; , s. 1037-1042
-
Konferensbidrag (refereegranskat)abstract
- Wide band characterization of analog-digital converter integral nonlinearity (INL) based on parametric modeling and least-squares parameter fit is performed. In particular, the variations in the INL due to the frequency of theADC stimuli are modeled. The INL is divided into two main entities describing the static and dynamic behavior of theADC, respectively. The static component is modeled by a high code component (HCF) of piecewise linear segmentscentered around zero. A static low code (LCF) polynomial inherent to the INL data is added to the segments to complete the static part of the model. The INL dynamic part is modeled by an LCF polynomial. Method implementationis considered and is applied to 12-bit ADC data at 210 MSPS.
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| 65. |
- Medawar, Samer, et al.
(författare)
-
Dynamic Calibration of Undersampled Pipelined ADCs by Frequency Domain Filtering
- 2013
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Ingår i: IEEE Transactions on Instrumentation and Measurement. - 0018-9456 .- 1557-9662. ; 62:7, s. 1882-1891
-
Tidskriftsartikel (refereegranskat)abstract
- Integral nonlinearity (INL) is used for the post-correction of pipelineanalog-digital converters (ADC)s. An input-frequency-dependentINL model is developed for the compensation. The model consistsof a static term that is dependent on the ADC output code and adynamic term that has an additional dependence on the input signalfrequency. The INL model is subtracted from thedigital output for post-correction. The static compensationis implemented with a look-up-table (LUT). The dynamic calibration isperformed by a bank of frequency domain filters using an overlap-add structure.Two ADCs of the same type (Analog Devices AD9430) are compensated in the first three Nyquist bands.The performance improvements in terms of spurious-free dynamic range(SFDR) and intermodulation distortion (IMD) are investigated. Using the proposed method, improvements up to 17 dB are reported in favorable scenarios.
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| 66. |
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| 67. |
- Medawar, Samer, et al.
(författare)
-
Input-Dependent Integral Nonlinearity Modeling for Pipelined Analog-Digital Converters
- 2010
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 59:10, s. 2609-2620
-
Tidskriftsartikel (refereegranskat)abstract
- Integral nonlinearity (INL) for pipelined analog-digital converters (ADCs) operating at RF is measured and characterized. A parametric model for the INL of pipelined ADCs is proposed, and the corresponding least-squares problem is formulated and solved. The INL is modeled both with respect to the converter output code and the frequency stimuli, which is dynamic modeling. The INL model contains a static and a dynamic part. The former comprises two 1-D terms in ADC code that are a sequence of zero-centered linear segments and a polynomial term. The 2-D dynamic part consists of a set of polynomials whose parameters are dependent on the ADC input stimuli. The INL modeling methodology is applied to simulated and experimental data from a 12-bit commercial ADC running at 210 mega samples per second. It is demonstrated that the developed methodology is an efficient way to capture the INL of nowadays ADCs running at RF, and it is believed that the methodology is powerful for INL-based ADC postcorrection in wideband applications.
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| 68. |
- Medawar, Samer, et al.
(författare)
-
Model order determination and segmentation of analog-digital converters integral non linearity
- 2010
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Ingår i: 2010 IEEE International Instrumentation and Measurement Technology Conference, I2MTC 2010. - IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA : IEEE. - 9781424428328 ; , s. 36-41, s. 36-41
-
Konferensbidrag (refereegranskat)abstract
- Analog-digital converter (ADC) integral nonlinearity (INL) modeling is investigated. The model is comprised of two entities: a low code frequency (LCF) component modeled by an L-order polynomial, and a static high code frequency component (HCF), modeled by P linear disjoint segments centered around zero. Both model components are functions of the ADC output code k. A methodical way of estimating the LCF polynomial order L and the set of segments (number of and their borders), is suggested. The method computes the polynomial order L and the set of segments (number and borders) that minimizes the root mean square (RMS) distance between the INL data and its model. The method is applied to measured INL sequences of a 12-bit Analog Devices pipeline ADC (AD9430).
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| 69. |
- Medawar, Samer, et al.
(författare)
-
Pipelined analog-digital converters integral nonlinearity modeling for post-correction
- 2010
-
Ingår i: 17th Symposium IMEKO TC4 - Measurement of Electrical Quantities, 15th International Workshop on ADC Modelling and Testing, and 3rd Symposium IMEKO TC19 - Environmental Measurements. - 9781617823381 ; , s. 585-590
-
Konferensbidrag (refereegranskat)abstract
- An input-dependent integral nonlinearity (INL) model is developed for pipeline ADC post-correction. The INL model consists of a static and dynamic part. The INL model is subtracted from the ADC digital output for compensation. Static compensation is performed by adjacent sets of gains and offsets. Each set compensates a certain output code range. The frequency content of the INL dynamic component is used to design a set of filter blocks that performs ADC compensation in the time domain. The compensation scheme is applied to measured data of two 12-bit ADCs of the same type (Analog Devices AD9430). Significant performance improvements in terms of spurious free dynamic range (SFDR) are obtained.
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| 70. |
- Medawar, Samer, et al.
(författare)
-
Post-correction of pipelined analog-digital converters based on input dependent integral nonlinearity modeling
- 2011
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 60:10, s. 3342-3350
-
Tidskriftsartikel (refereegranskat)abstract
- The integral nonlinearity (INL) is used for the postcorrection of analog-digital converters (ADCs). An input-frequency-dependent INL model is developed for the postcorrection. The model consists of a static term that is dependent on the ADC output code and a dynamic term that has an additional dependence on the input frequency. The concept of ADC digital output postcorrection by INL is first introduced. The INL model is subtracted from the digital output for postcorrection. The static compensation part is made by adjacent sets of gains and offsets, where each set corrects a range of output codes. The dynamic information, i.e., the frequency dependence of the INL dynamic component is used to construct a set of filter blocks that performs ADC compensation in the time domain. The compensation scheme is applied to the measured data of two ADCs of the same type (Analog Devices AD9430). Performance improvements in terms of spurious-free dynamic range, signal-to-noise and distortion ratio, intermodulation distortion, and noise are obtained. The dynamic compensation part, due to its frequency dependence, can be generalized; hence, a postcorrection block model can be used for compensating multiple ADCs of the same type.
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