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Power Gain (power + gain)
Selected AbstractsAdjoint network method applied to the performance sensitivities of microwave amplifiersINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2006F. Güne Abstract This work focuses on the performance sensitivities of microwave amplifiers using the "adjoint network and adjoint variable" method, via "wave" approaches, which includes sensitivities of the transducer power gain, noise figure, and magnitudes and phases of the input and output reflection coefficients. The method can be extended to sensitivities of the other performance measure functions. The adjoint-variable methods for design-sensitivity analysis offer computational speed and accuracy. They can be used for efficiency-based gradient optimization, in tolerance and yield analyses. In this work, an arbitrarily configured microwave amplifier is considered: firstly, each element in the network is modeled by the scattering matrix formulation, then the topology of the network is taken into account using the connection scattering-matrix formulation. The wave approach is utilized in the evaluation of all the performance-measurement functions, then sensitivity invariants are formulated using Tellegen's theorem. Performance sensitivities of the T- and ,-types of distributed-parameter amplifiers are considered as a worked example. The numerical results of T- and ,-type amplifiers for the design targets of noise figure Freq = 0.46 dB , 1,12 and Vireq = 1, GTreq = 12 dB , 15.86 in the frequency range 2,11 GHz are given in comparison to each other. Furthermore, analytical methods of the "gain factorisation" and "chain sensitivity parameter" are applied to the gain and noise sensitivities as well. In addition, "numerical perturbation" is applied to calculation of all the sensitivities. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006. [source] Expanding definitions of gain by taking harmonic content into account,INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2003Jeffrey Jargon Abstract We expand the definitions of power gain, transducer gain, and available gain by taking harmonic content into account. Furthermore, we show that under special conditions, these expanded definitions of gain can be expressed in terms of nonlinear large-signal scattering parameters. Finally, we provide an example showing how these expanded forms of gain and nonlinear large-signal scattering parameters can provide us with valuable information regarding the behavior of nonlinear models. Published 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13, 357,369, 2003. [source] Multiharmonic manipulation for highly efficient microwave power amplifiersINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2001Paolo Colantonio Abstract Multiharmonic manipulation is presented as the most effective solution to improve power amplifier (PA) efficiency performances. Remarkable improvements in output power, power gain and power-added efficiency (PAE) are demonstrated, properly manipulating the input and output second and third harmonics, as compared to more classical design approaches. Experimental results at 5GHz confirm the feasibility, the validity and effectiveness of the proposed approach, increasing the maximum measured power-added efficiency from 39% to 61% © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 366,384, 2001 [source] A 1-GHz GaN HEMT based class-E power amplifier with 80% efficiencyMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008Yong-Sub Lee Abstract This article reports a highly efficient 1-GHz class-E power amplifier based on a GaN HEMT. The compensation elements with a series capacitor and a shunt inductor are used to compensate for the internal parasitic components of the packaged transistor. To improve output power and efficiency by suppressing harmonic powers, an output matching circuit using the transmission lines is used. The peak PAE and drain efficiency of 79.2 and 80.4% with a power gain of 18.14 dB is achieved at an output power of 41.14 dBm for a continuous wave. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2989,2992, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23803 [source] Small size low noise amplifier with suppressed noise from gate resistanceMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2008Ickhyun Song Abstract In this article, design and characterization results of a fully integrated 5.8 GHz low noise amplifier (LNA) using 0.13-,m CMOS technology are presented. Commonly adopted inductive source degeneration for input impedance matching is eliminated to achieve smaller chip area while providing reasonable 50-, matching. Also by adding a capacitor between the gate and the source of the input transistor, a noise source from the gate resistance is partly suppressed. The layout of the designed LNA occupies total area of 0.68 mm2 and the results show forward power gain (S21) of 12.7 dB and noise figure of 3.9 dB while consuming 6.85 mW from 1.2-V DC supply. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2300,2304, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23702 [source] A 5.5-GHz SiGe HBT Doherty amplifier using diode linearizer and lumped-element hybrid couplerMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2008Haiwen Liu Abstract A 5.5-GHz Doherty amplifier using commercial 0.35-,m SiGe HBT technology is proposed in this article. To improve the linearity, a predistortion using diode linearizer is adopted for biasing the peak amplifier. Moreover, to realize in fully on-chip with circuit reduction, a 90° 3-dB hybrid coupler and quarter-wave transmission lines are implemented by lumped-elements. In this design, 819 ,m2 HBTs are used for carried and peak amplifiers, respectively, and 26 ,m2 HBT is used for linearizer. Results verify that the power gain, P1dB, and power added efficiency (PAE) of the proposed Doherty amplifier at 5.5 GHz are 8.4 dB, 31 dBm, and 30%, respectively. Also, the adjacent channel power ratio (ACPR) and the output signal's spectrum mask are given using the 54Mcps 64QAM modulated signal at 10 MHz offset. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1554,1558, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23432 [source] A high-efficiency class-E power amplifier using SiC MESFETMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2007Yong-Sub Lee Abstract This article reports a high efficiency class-E power amplifier using a SiC MESFET, which is designed and tested at 2.14 GHz. To improve output power and efficiency by suppressing harmonic powers, an output matching circuit using the transmission lines is used. From measured results for a single tone, the harmonic power levels are maintained below ,58 dBc at a whole output power level. The peak power-added efficiency of 72.3% with a power gain of 10.27 dB is achieved at an output power of 40.27 dBm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1447,1449, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22455 [source] An analysis of layout and temperature effects on magnetic-coupling factor, resistive-coupling factor, and power gain performances of RF transformers for RFIC applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2006Yo-Sheng Lin Abstract In this paper, we demonstrate a comprehensive analysis of the temperature effect (from ,25°C to 175°C) on the quality-factors (Q1 and Q2), magnetic-coupling factor (KIm), resistive-coupling factor (KRe), maximum available power gain (GA max), and minimum noise figure (NFmin) performances of RF bifilar and stacked transformers for RFIC applications. Excellent GA max of 0.713 and 0.806 (that is, NFmin of 1.469 and 0.937 dB) were achieved at 5 and 7 GHz, respectively, at room temperature, for a 1:1 stacked transformer mainly due to its high KIm and KRe. In addition, for the 1:1 bifilar transformer at room temperature, though its KIm and KRe are low, good GA max of 0.636 and 0.631 (that is, NFmin of 1.965 and 2.0 dB) were still achieved at 5 and 7 GHz, respectively, mainly due to its high Q1 and Q2. The present analysis is helpful for RF engineers to design temperature-insensitive ultra-low-voltage high-performance transformer-feedback low-noise-amplifiers (LNAs) and voltage-controlled-oscillators (VCOs), and other radio-frequency integrated circuits (RF-ICs) which include transformers. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1460,1466, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21732 [source] Inferring Haplotype/Disease Association by Joint Use of Case-Parents Trios and Case-Parent PairsANNALS OF HUMAN GENETICS, Issue 3 2010Yue-Qing Hu Summary Recently interest has been increasing in genetic association studies using several closely linked loci. The HAP-TDT method, which uses case-parents trios is powerful for such a task. However, it is not uncommon in practice that one parent is missing for some reason, such as late onset. The case-parents trios are thus reduced to case-parent pairs. Discarding such data could lead to a severe loss of power. In this paper, we propose the HAP-1-TDT method based on case-parent pairs to detect haplotype/disease association. A permutation-based randomisation technique is devised to assess the significance of the test statistic. Furthermore, the combined statistic HAP-C-TDT is developed to use jointly case-parents trios and case-parent pairs. These test statistics can be applied to either phase-known or phase-unknown data. A number of simulation studies are conducted to investigate the validity of the proposed tests; these studies show that the statistics are robust to population structure. Using several disease genes from the literature, we illustrate that incorporating case-parent pairs into an association study leads to noticeable power gain. Moreover, our simulation results suggest that our method has better size and power than UNPHASED. Finally, in simulated scenarios where there are only a few SNPs and risk is determined by two haplotypes that are complementary or near-complementary, our method has better power than TRIMM. [source] New Powerful Approaches for Family-based Association Tests with Longitudinal MeasurementsANNALS OF HUMAN GENETICS, Issue 1 2009Xiao Ding Summary We discuss several new powerful family-based approaches for testing genetic association when the traits are obtained from longitudinal or repeated measurement studies. The popular approach FBAT-PC is based on a linear combination of the individual traits. We propose a one-sided modification, FBAT-PCM, which has a closed-form expression and is always more powerful. We also present two approaches FBAT-LC and FBAT-LCC based on linear combination of the univariate test statistics. Furthermore, all three approaches are shown to be unified to a general form. Through simulation studies, we compare the power of these tests under different models of genetic effect sizes. Compared to original FBAT-PC, our modification achieves a power gain of up to 50%. In addition, all three new approaches gain substantial power compared to the ordinary approach of Bonferroni correction, with the relative performance depending upon the underlying model. Application of these approaches for testing an association between Body Mass Index and a previously reported candidate SNP confirms our results. [source] Testing Association with Interactions by Partitioning Chi-SquaresANNALS OF HUMAN GENETICS, Issue 1 2009Y. Yang Summary Gene-gene interaction plays an important role in association studies for complex diseases. There have been different approaches to incorporating gene-gene interactions in candidate gene or genome-wide association studies, especially for those genes with no marginal effects but with interaction effects. However, there is no general agreement on how interaction should be tested and how main effects and interaction effects act on a significance signal. In this paper, we propose a test of the null hypothesis of no association in terms of interaction effects for two unlinked loci, which is a 4 degrees of freedom (df) chi-square for two SNPs. The test, derived by contrasting inter-locus disequilibrium measures between cases and controls, can be viewed as the interaction component of the total Pearson chi-square. The remaining portion of the total chi-square can also be used for association analysis, which emphasizes main effects. Simulation studies show that in most situations our interaction test is similar in power to the test based on a logistic regression model but has more power when the genes have no marginal effects. Results also show that single-locus marginal tests can lose much power if interaction effects dominate main effects. For some specific genetic models, the interaction test may be further partitioned into four 1-df chi-squares for individual interaction effect. The interaction pattern can best be demonstrated by the 1-df chi-square components. Simulation results show that there is substantial power gain if interaction patterns are properly incorporated in association analysis. [source] Modeling maternal-offspring gene-gene interactions: the extended-MFG testGENETIC EPIDEMIOLOGY, Issue 5 2010Erica J. Childs Abstract Maternal-fetal genotype (MFG) incompatibility is an interaction between the genes of a mother and offspring at a particular locus that adversely affects the developing fetus, thereby increasing susceptibility to disease. Statistical methods for examining MFG incompatibility as a disease risk factor have been developed for nuclear families. Because families collected as part of a study can be large and complex, containing multiple generations and marriage loops, we create the Extended-MFG (EMFG) Test, a model-based likelihood approach, to allow for arbitrary family structures. We modify the MFG test by replacing the nuclear-family based "mating type" approach with Ott's representation of a pedigree likelihood and calculating MFG incompatibility along with the Mendelian transmission probability. In order to allow for extension to arbitrary family structures, we make a slightly more stringent assumption of random mating with respect to the locus of interest. Simulations show that the EMFG test has appropriate type-I error rate, power, and precise parameter estimation when random mating holds. Our simulations and real data example illustrate that the chief advantages of the EMFG test over the earlier nuclear family version of the MFG test are improved accuracy of parameter estimation and power gains in the presence of missing genotypes. Genet. Epidemiol. 34: 512,521, 2010.© 2010 Wiley-Liss, Inc. [source] More powerful panel data unit root tests with an application to mean reversion in real exchange ratesJOURNAL OF APPLIED ECONOMETRICS, Issue 2 2004L. Vanessa Smith Unit root tests, seeking mean or trend reversion, are frequently applied to panel data. We show that more powerful variants of commonly applied tests are readily available. Moreover, power gains persist when the modifications are applied to bootstrap procedures that may be employed when cross-correlation of a rather general sort among individual panel members is suspected. Copyright © 2004 John Wiley & Sons, Ltd. [source] Can panel data really improve the predictability of the monetary exchange rate model?JOURNAL OF FORECASTING, Issue 5 2007Joakim Westerlund Abstract A common explanation for the inability of the monetary model to beat the random walk in forecasting future exchange rates is that conventional time series tests may have low power, and that panel data should generate more powerful tests. This paper provides an extensive evaluation of this power argument to the use of panel data in the forecasting context. In particular, by using simulations it is shown that although pooling of the individual prediction tests can lead to substantial power gains, pooling only the parameters of the forecasting equation, as has been suggested in the previous literature, does not seem to generate more powerful tests. The simulation results are illustrated through an empirical application. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||||||||