Diseño y optimización de ruido de fase en osciladores utilizando la NDF.

In this paper the use of the NDF is proposed as a general method suitable for analysing any oscillator topology. The most important advantage of this method is that it provides an unique procedure to analyse any oscillator. It also makes possible the phase noise optimization in the linear design phase for any oscillator. An additional advantage of this method is that it does not require any proviso verification as all classic methods need. The use of the NDF method is illustrated with the design of two examples. These two oscillators are manufactured and the simulation results are compared with the measurements showing good agreement. These results confirm the excellent possibilities of the proposed method for low noise oscillators design

Low-cost measurement for a secondary Mode S radar transmitter

A low-cost, multiple-purpose, and high-precision timing test setup for the measurements of secondary Mode S radar transmission signal was proposed. The goal was to fully guarantee compliance of the proposed transmitter under test with the really hard International Civil Aircraft Organization requirements using traditional measurement equipment, which was difficult or even impossible to ensure up to now. The low-cost structure proposed in this paper allows the user to perform measurements independently of the measurements performed by the pieces of test equipment shelled by the manufacturer of radar, which is a very important aspect since the independence of the verifications is a mandatory requirement established by the safety standards of civil aviation. The proposed setup has been used to verify several transmitters with some defects that are not detected by monopulse secondary surveillance radar specific pieces of test equipment that are focused on more high-level functionalities. It also is valid and it has been used, as a general-purpose setup, for testing other radio navigation aids

Contributions and reflections to the study of stability and oscillation of active antennas

This thesis was carried out in the DIEMAG Group and TSC department of ETSI y Sistemas de Telecomunicación from Universidad Politécnica de Madrid. Its title is “Contributions and Reflections to the Study of Stability and Oscillation of Active Antennas” and it has been developed by Angel Parra Cerrada, Electrical Engineer MSc, under the supervision of Prof. Vicente Gonzalez Posadas, PhD and Prof. Jose Luis Jimenez Martin, PhD. The current interest on active antennas is very important, mainly on small antennas and integrated antennas. The patch antennas are maybe the type of integrated antennas more used at present designs. The design of active patch antennas must always include a study of stability, because they must be stable for amplifier function or because they must oscillate in a proper way for TX-oscillator, mixing-oscillator, etc. The fundamental aspects of analysis of patches and their modes are covered in a general review. The modes and internal fields of the patches are fundamental for the proper understanding of the radiation diagram, impedance at the feed point, interaction with active elements and compatibility with the feeding uses for active functions. The main problem to study the stability of any circuit is as several authors have pointed out that “there is not a compact formulation of an oscillation criterion that is both necessary and sufficient”. The linear methods for the study of the stability of the RF circuits are reviewed and the conditions for their proper use, limitations and problems are exposed and summarized. The presentation of a new method based on the NDF for the linear stability analysis is a significant contribution of this work. This proposed method is used for several designs of active antennas and compared with classic linear methods, non-linear simulations and measurements. These comparatives state the NDF Method as correct predictor of stability, but not the classic linear methods. The new proposed NDF Method is a compact procedure that is necessary and sufficient criterion on the study stability. There are multiple elements that can be used to tune or control the impedance of the patches. Two of these elements are the metamaterials (passive) and the Negative Impedance Converters, NIC (active). The inclusion of these elements on active patches and their implications on the stability of active patches are studied using the NDF Method and the classic methods. The results outcome that the use of NICs built with discrete transistors is a high risk for the stability. The proposed NDF Method opens a new way for the research of new oscillators, active antennas and low phase noise oscillator topologies. The lack of additional conditions (proviso) for the use of the NDF Method provides it the advantage of being a universal method for studying the linear stability of any topology of oscillator or active antenna. The thesis covers in detail the field of the stability of integrated active patch antennas. This study of the stability is disseminated with multiple publications as it is detailed in the contributions section. RESUMEN Esta tesis ha sido realizada en el Grupo DIEMAG y en el Departamento TSC de la ETSIS y Sistemas de Telecomunicación de la Universidad Politécnica de Madrid. Su titulo es “Contributions and Reflections to the Study of Stability and Oscillation of Active Antennas” (Contribuciones y Reflexiones al Estudio de la Estabilidad y Oscilación de Antenas Activas) y ha sido realizada por Angel Parra Cerrada, Ingeniero de Telecomunicación (MSc), bajo la dirección de el Prof. Dr. Vicente Gonzalez Posadas y el Prof. Dr. Jose Luis Jimenez Martin. Hoy en día existe un gran interés en el campo de las antenas activas, especialmente en las antenas integradas y de pequeño tamaño. Posiblemente, las antenas de parche sean, al día de hoy, las antenas más utilizadas en los nuevos diseños. El diseño de antenas activas siempre debe incluir un análisis de su estabilidad, ya que esta debe ser estable para aplicaciones como la amplificación e inestable de forma controlada para otras como oscilador, mezclador-oscilador, etc. Los principales aspectos del análisis de los parches y de sus modos se cubren en una presentación general de estos. Conocer los campos internos de los parches es imprescindible para poder tener un correcto entendimiento de los diagramas de radiación, impedancia de entrada, interacción con los elementos activos y compatibilidad con puntos de acoplo al parche usados por los elementos activos. El mayor problema para el estudio de la estabilidad de cualquier circuito es, como declaran diversos autores, “no existe una formulación compacta del criterio de oscilación que sea condición necesaria y suficiente” . Se realiza una revisión de los métodos clásicos de análisis lineal de la estabilidad de circuitos de RF y se enumeran y resumen sus condiciones para un uso apropiado, limitaciones y problemas. Una importante aportación de esta tesis es la presentación de nuevo método lineal de análisis de estabilidad basado en la NDF. El método propuesto es utilizado en el diseño de varias antenas activas; y los resultados de este análisis, de los análisis con los métodos clásicos, de los análisis no lineales y de las medidas son comparados. Estas comparaciones demuestran que el método basado en la NDF es una herramienta correcta para el análisis de estabilidad, mientras que los métodos clásicos no lo son. Este nuevo método basado en la NDF es un método compacto que es un predictor necesario y suficiente para el estudio de la estabilidad. Existen múltiples elementos que pueden ser utilizados para ajustar y controlar la impedancia de los parches. Dos de estos elementos son los metamateriales (pasivos) y los Conversores de Impedancia Negativa, NIC (activo). Las implicaciones y efectos de incluir estos elementos en parches activos se han estudiado utilizando el método basado en la NDF y los métodos clásicos. Los resultados demuestran que los NICs realizados con transistores discretos presentan un elevado riesgo de inestabilidad. El método basado en la NDF que se ha propuesto posibilita nuevos caminos para la búsqueda de nuevas topologías de osciladores, antenas activas y osciladores de bajo ruido. El no requerir ninguna condición previa (proviso) para utilizar el método basado en la NDF, le confiere a este la ventaja de ser un método universal para el estudio de la estabilidad valido para cualquier topología de osciladores y antenas activas. En esta tesis se desarrolla en detalle el estudio de la estabilidad y antenas activas. Este estudio de la estabilidad se ha difundido ampliamente con múltiples publicaciones, tal como se detalla en el capítulo de Contribuciones

Broadband (1-16 GHz) Balanced MMIC GaAs pHEMT LNA for Radio Astronomy Applications

A broadband (1-16 GHz) balanced MMIC low noise amplifier (LNA) using 100?nm GaAs pHEMT technology is presented in this paper. The proposed topology has been designed and manufactured under and OMMIC or UMS process with a drain voltage of 3,5 V. The simulated gain is 28 dB in the whole bandwidth and the DC power consumption is 280 mW. The simulated room-temperature noise performance is lower than 1.25 dB from 1 to 14 GHz and lower than 1.5 dB in the whole bandwidth while its figure of merit (FOM) is 86 (GHz/mW)

Stability analysis and design of negative impedance converters: application to circuit and small antennas

Negative impedance converters (NICs) have been proposed as structures to improve the performance of RF circuits and electrically small antennas. However, NICs suffer from stability problems. This paper presents a compact procedure to analyze the stability of NICs. Then, the required and sufficient conditions to predict the stability of a negative impedance converter are given. These conditions can be evaluated using standard computer-aideddesign software. Finally, a NIC prototype is given to validate and illustrate the presented design procedure, it is also integrated with a printed, blade-type, electrically small monopole in the VHF band