14 research outputs found

    Linealización a nivel de dispositivo mediante la utilización del comportamiento gran señal de los FET´s

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    Important efforts are currently being made on linear amplification, and novel techniques are being developed, based on the transistor characteristics. This paper proposes the use of the large-signal behavior of the in-band intermodulation distortion (IMD) components in FET devices for linearization of class B amplifiers

    Evolución de los mínimos de IMD en transistores HEMT´s: descripción usando una GM3 variante en el tiempo

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    In this paper, an alternative description of the small- to large-signal intermodulation distortion (IMD) evolution in PHEMT amplifiers is presented. The influence of the device derivatives on the nulls of the in-band distortion components of the channel current, and the origin of the linearity sweet spots are evaluated using the timedependence of the drain to source current third order derivatives as a novel technique for IMD null prediction

    Uso de los sweet-spots de gran señal en funciones de control de potencia de alta linealidad

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    In this paper a novel technique for controlling the output power in class B amplifiers is presented. The new approach uses the large-signal sweet-spots that appear in this operation mode, to optimize the linear behavior of the device and improve the amplifier power efficiency over the complete control range. A control strategy, based in a dual bias adjustment along the sweet-spots loci, is proposed to guarantee, at the same time, high linearity and high efficiency

    Control del comportamiento en distorsión de intermodulación en un pHEMT de enriquecimiento

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    In this paper, an Enhancement-mode Pseudomorphic HEMT has been characterized in terms of its intermodulation distortion behaviour. Small-signal parameters are extracted using a laboratory characterization procedure and applying Volterra Series analysis. We have also studied large-signal IMD3 performance, particularly taking the linearity sweet-spot behaviour into account. The potentialities of this device for highly linear applications have been remarked

    Mezcladores simplemente balanceados usando un dispositivo E-PHEMT sin polarización

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    Two zero-bias single-device singly-balanced mixers, using an Enhancement Mode Pseodomorphic HEMT (E-PHEMT), are proposed in this paper. The first mixer takes advantage of the time-varying output conductance of the device, when excited at gate with a local oscillator (LO) signal, while the other uses the timevarying transconductance produced by a drain-to-source LO excitation

    Antena polarizada circularmente con control de ganancia y alta linealidad

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    In this paper, a novel highly linear circularly polarized active antenna with gain control is presented. In this approach, the antenna serves as a 90º hybrid and the active part has been implemented using a branch line coupler as the 90º input hybrid circuit, and two PHEMT based amplifiers. The amplifiers are based on a new strategy for gain control with low distortion

    Characterizing the Linearity Sweet-Spot Evolution in FET Devices

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    In this paper,a complete characterization of the linearity sweet-spot evolution in MESFET/HEMT devices is presented. A global experimental extraction of the I ds(V gs,V ds) Taylor series coefficients is used tointroduce the small-signal behavior in the linear and saturated regions. The possibility of taking advantage of these points in different applications is also discussed. For the first time, a characterization of the influence of both bias voltages on the device transition towards the large-signal regime is presented. Finally, a technique for improving the linearity-efficiency tradeoff in a class B/C power amplifier (PA) is introduced

    A novel approach for highly linear automatic gain control of a hemt small-signal amplifier

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    A novel approach for highly linear automatic gain control (AGC) in small-signal ampli¯ers is presented in this paper. A HEMT based topology was implemented, biasing the transistor in the transition between the saturated and linear operation regions. Gain control with low distortion is achieved by simultaneous adjustments of the gate to source (Vgs) and drain to source (Vds) voltages, along the line where the second derivative of the transconductance (Gm3) has a null. Comparatively to the traditional approach, with the transistor biased in the saturated region, this ampli¯er has better intermodulation behavior and e±ciency, without important reduction in the gain control range

    Información Investigador: Malaver, Emigdio Antonio

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    DoctoradoMarzo de 2007Ingeniero Electricista+58 274 2402910Facultad de Ingenierí[email protected]

    Control automático de ganancia con baja intermodulación y alta eficiencia

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    We present a novel approach for highly linear automatic gain control (AGC) of a HEMT small-signal amplifiers. The amplifier was implemented, with the transistor biased in the transition between the saturated and lineal operation regions. Gain control with low distortion is achieved by simultaneous adjustments of the gate to source (Vgs) and drain to source (Vds) voltages along the line where the second derivative of the transconductance (Gm3) has a null. We realized a comparative analysis of the performance of our proposal versus an amplifier designed following a traditional approach. With our approach we obtained a better performance in terms of intermodulation and power-efficiency, without an important reduction in the gain control range
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