The Experts below are selected from a list of 5184 Experts worldwide ranked by ideXlab platform
Gary J. Berkel - One of the best experts on this subject based on the ideXlab platform.
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Expanded use of a battery-powered two-electrode Emitter cell for electrospray mass spectrometry
Journal of The American Society for Mass Spectrometry, 2006Co-Authors: Vilmos Kertesz, Gary J. BerkelAbstract:A battery-powered, controlled-current, two-electrode electrochemical cell containing a porous flow-through working electrode with high surface area and multiple auxiliary electrodes with small total surface area was incorporated into the electrospray Emitter Circuit to control the electrochemical reactions of analytes in the electrospray Emitter. This cell system provided the ability to control the extent of analyte oxidation in positive ion mode in the electrospray Emitter by simply setting the magnitude and polarity of the current at the working electrode. In addition, this cell provided the ability to effectively reduce analytes in positive ion mode and oxidize analytes in negative ion mode. The small size, economics, and ease of use of such a battery-powered controlled-current Emitter cell was demonstrated by powering a single resistor and switch Circuit with a small-size, 3 V watch battery, all of which might be incorporated on the Emitter cell.
Vilmos Kertesz - One of the best experts on this subject based on the ideXlab platform.
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Expanded use of a battery-powered two-electrode Emitter cell for electrospray mass spectrometry
Journal of The American Society for Mass Spectrometry, 2006Co-Authors: Vilmos Kertesz, Gary J. BerkelAbstract:A battery-powered, controlled-current, two-electrode electrochemical cell containing a porous flow-through working electrode with high surface area and multiple auxiliary electrodes with small total surface area was incorporated into the electrospray Emitter Circuit to control the electrochemical reactions of analytes in the electrospray Emitter. This cell system provided the ability to control the extent of analyte oxidation in positive ion mode in the electrospray Emitter by simply setting the magnitude and polarity of the current at the working electrode. In addition, this cell provided the ability to effectively reduce analytes in positive ion mode and oxidize analytes in negative ion mode. The small size, economics, and ease of use of such a battery-powered controlled-current Emitter cell was demonstrated by powering a single resistor and switch Circuit with a small-size, 3 V watch battery, all of which might be incorporated on the Emitter cell.
Costa, Luciano Da F. - One of the best experts on this subject based on the ideXlab platform.
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Towards a Simple, and Yet Accurate, Transistor Equivalent Circuit and Its Application to the Analysis and Design of Discrete and Integrated Electronic Circuits
2018Co-Authors: Costa, Luciano Da F.Abstract:Transistors are the cornerstone of modern electronics. Yet, their relatively complex characteristics, allied with often observed great parameter variation, remain a challenge for discrete and integrated electronics. Much of transistor research and applications have relied on transistor models, as well as respective equivalent Circuits, to be employed for Circuit analysis and simulations. Here, a simple and yet accurate transistor equivalent Circuit is derived, based on the Early effect, which involves only the voltage $V_a$ and a companion parameter $s$. Equations are obtained for currents and voltages in a common-Emitter Circuit, allowing the derivation of respective gain functions. These functions are found to exhibit interesting mathematical structure, with gain values varying almost linearly with the base current, allowing the gains to be well characterized in terms of their average and variation values. These results are applied to deriving a prototypic Early space summarizing the characteristics of transistors, enriched with recently experimentally obtained prototypes of NPN and PNP silicon BJTs and alloy germanium transistors. Though a trade-off between gain and linearity is revealed, a band characterized by small values of $V_a$ stands out when aiming at both high gain and low distortion. The Early equivalent model was used also for studying the stability of Circuits under voltage supply oscillations, as well as parallel combinations of transistors. In the former case, it was verified that more traditional approaches assuming constant current gain can yield stability factors that deviate substantially from those derived for the more accurate Early approach. The equivalent Circuit obtained for parallel combinations of transistors was shown also to closely follow the Early formulation.Comment: A working manuscript with 15 pages and 19 figure
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On the Effects of Resistive and Reactive Loads on Signal Amplification
2018Co-Authors: Costa, Luciano Da F.Abstract:The effects of reactive loads into amplification is studied. A simplified common Emitter Circuit configuration was adopted and respective time-independent and time-dependent voltage and current equations were obtained. As phasor analysis cannot be used because of the non-linearity, the voltage at the capacitor was represented in terms of the respective integral, implying a numerical approach. The effect of purely resistive loads was investigated first, and it was shown that the fanned structure of the transistor isolines can severely distort the amplification, especially for $V_a$ small and $s$ large. The total harmonic distortion was found not to depend on $V_a$, being determined by $s$ and the load resistance $R$. An expression was obtained for the current gain in terms of the base current and it was shown that it decreases in an almost perfectly linearly fashion with $I_B$. Remarkably, no gain variation, and hence perfectly linear amplification, is obtained when $R=0$, provided maximum power dissipation limits are not exceeded. Capacitive loads imply the detachment of the Circuit trajectory from a straight line to an "ellipsoidal"-like loop. This implies a gain asymmetry along upper or lower arcs of this loop. By using the time-dependent Circuit equations, it was possible to show numerically and by an analytical approximation that, at least for the adopted Circuit and parameter values, the asymmetry induced by capacitive loads is not substantial. However, capacitive loads will imply lag between the output voltage and current and, hence, low-pass filtering. It was shown that smaller $V_a$ and larger $s$ can substantially reduce the phase lag, but at the cost of severe distortion.Comment: A working manuscript with 13 pages and 13 figure
Brian Floyd - One of the best experts on this subject based on the ideXlab platform.
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a 77 ghz sige power amplifier for potential applications in automotive radar systems
Radio Frequency Integrated Circuits Symposium, 2004Co-Authors: Ullrich R Pfeiffer, Scott K Reynolds, Brian FloydAbstract:We present the performance of a 77 GHz power amplifier for potential applications directed towards automotive radar systems. The Circuit was fabricated in a SiGe bipolar preproduction technology. A balanced two-stage common Emitter Circuit topology was used to achieve 6.1 dB of power gain at 77 GHz and 11.6 dBm output power at 1dB compression. The power amplifier uses a single 2.5 V supply and was fully integrated (including matching elements) to demonstrate its low-cost potential. First experimental results show its broadband characteristic from 40 GHz to 80 GHz and its temperature dependence up to 130/spl deg/C.
Ullrich R Pfeiffer - One of the best experts on this subject based on the ideXlab platform.
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a 77 ghz sige power amplifier for potential applications in automotive radar systems
Radio Frequency Integrated Circuits Symposium, 2004Co-Authors: Ullrich R Pfeiffer, Scott K Reynolds, Brian FloydAbstract:We present the performance of a 77 GHz power amplifier for potential applications directed towards automotive radar systems. The Circuit was fabricated in a SiGe bipolar preproduction technology. A balanced two-stage common Emitter Circuit topology was used to achieve 6.1 dB of power gain at 77 GHz and 11.6 dBm output power at 1dB compression. The power amplifier uses a single 2.5 V supply and was fully integrated (including matching elements) to demonstrate its low-cost potential. First experimental results show its broadband characteristic from 40 GHz to 80 GHz and its temperature dependence up to 130/spl deg/C.