1,721,039 research outputs found
Electrical measurement of the junction temperature and thermal resistance of HBTs
No full textA simple method is proposed to derive the junction temperature and the bias- and temperature-dependent thermal resistance of heterojunction bipolar transistors (HBTs) using a radio frequency (RF) signal. The method exploits the thermal dependence of the current gain of a transistor whose dissipated power is modified by applying an RF signal. The new method is used to derive the junction temperature and thermal resistance of a power HBT. The results are compared with state-of-the-art techniques
Parametric analysis on the design of RF mems series switches
No full textA parametric analysis on the design of RF MEMS series switches is performed. The main design variables were identified and a set of RF MEMS series switches were designed, fabricated and measured. The effect of these design variables on the pull-in voltage (Vp) and the RF performance of the switches is studied and simplified equations for design propose are evaluated and corrected on the basis of experimental results.Fil: Lonac, Julio Andrés. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Merletti, Gustavo Ariel. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
12-W X-Band MMIC HPA and Driver Amplifiers in InGaP-GaAs HBT Technology for Space SAR T/R Modules
No full textThe chip-set for the transmitting power lineup of satellite SAR antenna T/R modules has been designed and implemented exploiting a 2- μm GaInP-GaAs heterojunction bipolar transistor (HBT) technology suitable for space applications. The HBT technology features an integrated emitter ballast resistor that enables high-power density operation without suffering thermal runaway phenomena. Two monolithic microwave integrated circuit (MMIC) driver amplifiers and a MMIC HPA are described: the drivers exhibit small-signal gains exceeding 21 dB and P1 dB output power of about 28 and 29 dBm, respectively, in a 2-GHz bandwidth and CW condition. The HPA delivers more than 40-dBm power at about 2.5-dB gain compression and power-added efficiency (PAE) exceeding 36% in a 700-MHz bandwidth in pulsed operation. Its peak performance at the center of the band are 40.9-dBm output power and 45% PAE. These performance are obtained within tight de-rating conditions for space applications
A simple technique for measuring the thermal impedance and the thermal resistance of HBTs.
No full textThis paper presents a new and simple method for characterizing the thermal behavior ofHeterojunction Bipolar Transistors, based on DC, AC andlow frequency small signal measures of H (hybrid)parameters. Static characterization of the thermal behavioris achieved through the calculation of a thermal resistance, while a thermal impedance is used to describe thermaldynamic behavior. Validation results for the method obtained from both simulations and experimental data areincluded in the paper for a 10x2x40 µm InGaP/GaAs power HBT
Numerically Efficient Design of Highly Linear Microwave Power Amplifiers
No full textA recently proposed approach for the
prediction of power amplifier (PA) intermodulation
distortion (IMD) on the basis of single-tone Harmonic
Balance simulations is used in this paper for the definition
of a numerically efficient design procedure of highly linear
microwave power amplifiers. In particular, it is shown how
standard design goals on third or fifth order
intermodulation products, usually involving timeconsuming
two-tone HB analyses, are more simply but with
sufficient accuracy taken into account by means of faster
single-tone HB analyses in the iterative design process. The
proposed procedure is compared with standard approaches
in the design case of single-transistor and multiple
paralleled-transistors MMIC amplifiers, showing dramatic
reductions in computation time
Comparison between equivalent-circuit and black-box non-linear models for microwave electron devices
No full textBlack-box and Equivalent-circuit electron device models present different advantages. The first ones are independent from process and device technology (i.e, GaAs, InP, GaN). In the other side the black-box model extraction procedure could not be changed and modified, thus a “post-tune” procedure is not possible. On the contrary, equivalent circuits are strongly technology dependent, though they are more flexible in the identification procedure. In fact an “optimization” of the extracted model parameters is possible following a trade-off with measured data over a large set of bias conditions and frequencies. In this paper two device models, which represent the two categories, will be compared pointing out the differences in the extraction procedures and in the achievable accuracy under small-signal and large-signal operating conditions
Compact empirical modeling of nonlinear dynamic thermal effects in electron devices
No full textAn original empirical approach to deal with nonlinear
dynamic thermal effects in electron devices is proposed. The new
technology-independent approach is very compact and easy to implement in computer-aided design tools. Therefore, it can be easily
coupled with electrical device models in order to obtain accurate
electrothermal models that are suitable for nonconstant-envelope
RF applications (e.g., pulsed radar). Model equations and identification
procedures are derived in this paper. Validation results and
comparison with simplified models are also presented both for a
simulated field-effect transistor device, as well as for a real heterojunction bipolar transistor device
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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