A Digital Predistortion Technique Based on a NARX Network to Linearize GaN Class F Power Amplifiers (poster)

This work presents a novel Digital Predistortion (DPD) scheme based on a NARX network, suitable for linearizing power amplifiers (PAs). The NARX network is a Recurrent Neural Network (RNN) with embedded memory that allows efficient modeling of nonlinear systems. Its neural architecture is very effective to model long term dependencies, such as the typical memory effects of PAs. To demonstrate the feasibility of the NARX network as a DPD system, a GaN class F PA with two LTE signals with 5 MHz of bandwidth is used. Experimental results show a distortion correction better than 10 dB

APLICACIÓN EN MATLAB DE UN SISTEMA ENVELOPE LOAD PULL PARA CARACTERIZACIÓN DE IMPEDANCIAS (MATLAB APLICATION OF AN ENVELOPE LOAD PULL SYSTEM FOR IMPEDANCE CHARACTERIZATION)

Resumen En este artículo se presenta la simulación de un sistema de cargas activas en el software Simulink, con el método Envelope Load Pull, con el cual se realizan mediaciones precisas para caracterizar las impedancias de un dispositivo. El desacople de impedancias en alta frecuencia genera una alteración en magnitud y fase de la señal incidente la cual alterara la información que se desea transmitir. Para evitar este efecto se debe acoplar una impedancia que permita tanto una máxima transferencia de potencia como contrarrestar las reactancias del sistema, para esto, se debe caracterizar el sistema en términos de corriente, voltaje o potencia para dar una descripción precisa del comportamiento de la impedancia del dispositivo. Muchos métodos para realizar la caracterización consisten en evaluar en comportamiento de la señal reflejada al presentarle diferentes cargas, ya sea, pasivamente al presentarle resistencias y reactancias o activamente al modificar la salida con señales de voltaje. Palabras Clave: Caracterización de impedancias, cargas activas, envelope load pull, Matlab, simulación. Abstract This article presents the simulation of an active load system in the Simulink software, using the Envelope Load Pull method, with which precise measurements are performed to characterize the impedances of a device. The decoupling of high frequency impedances generates an alteration in magnitude and phase of the incident signal which alters the information to be transmitted. To avoid this effect, an impedance that allows both maximum power transfer and counteract the reactions of the system must be coupled, for this, the system must be characterized in terms of current, voltage or power to give an accurate description of the behavior of the impedance. Of the device. Many methods to perform the characterization consisting in evaluating the behavior of the reflected signal when presenting different loads, either passively when presenting resistances and reactances or actively when modifying the output with voltage signals. Keywords: Active loads, envelope load pull, Impedance characterization, Matlab, simulation

DISEÑO DE INTERFAZ GRÁFICA PARA EVALUACIÓN DE ESQUEMAS DE MODULACIÓN (GRAPHIC INTERFACE DESIGN FOR THE EVALUATION OF MODULATION SCHEMES)

Resumen Este artículo presenta el desarrollo de una interfaz gráfica de usuario para la evaluación de los esquemas de modulación AM, FM, PM, BLU, DBL, PSK, BPSK, QPSK, QAM y DSSS. Estas técnicas se desarrollan mediante scripts de Matlab y desde la plataforma de Simulink. La contribución principal de este trabajo de investigación radica en la facilidad con que los esquemas de modulación pueden ser evaluados y comparados utilizando diferentes tipos de datos como mensajes. El objetivo es analizar los tiempos de modulación dependiendo del tipo de mensaje, así como comparar la cantidad de símbolos requeridos para el caso de las modulaciones BPSK, QPSK y QAM. En la introducción de datos se predefinen diez diferentes tipos de mensaje en la ventana de selección a las cuales se les puede modificar ciertos parámetros básicos como amplitud y frecuencia. La interfaz cuenta con menús desplegables por lo que es sencillo introducir los parámetros y esquemas a evaluar. Palabras Clave: Interface gráfica, Matlab, Modulación analógica, Modulación digital, Parámetros, Portadora. Abstract This article presents the development of a graphical user interface for evaluating AM, FM, PM, SSB, DBL, PSK, BPSK, QPSK, QAM, and DSSS modulation schemes. These techniques are developed using Matlab scripts from the Simulink platform. The main contribution of this research lies in the ability that modulation schemes can be evaluated and compared using different data types as messages. The objective is to analyze the modulation times depending on message type, as well as to compare the number of symbols required for the BPSK, QPSK, and QAM modulations. In the data entry, ten different types of messages are predefined in the selection window where certain basic parameters such as amplitude and frequency can be modified. The graphical user interface has displayed menus so it is easy to introduce the parameters and schemes to be evaluated. Keywords: Analog modulation, Carrier, Digital modulation, Graphical interface, Matlab, Parameters

Metodología de diseño basada en FPGA para la predistorsión digital de amplificadores de potencia

Este artículo describe el diseño e implementación de un sistema de predistorsión digital (DPD) sin memoria para la linealización de amplificadores de potencia. El prototipo del sistema y la arquitectura se implementaron usando un kit de desarrollo DSP-FPGA. La metodología de diseño es descrita en bloques prácticos y analizada en detalle con énfasis especial en el dominio digital, donde se ejecutaron los algoritmos propuestos. La estrategia del sistema predistorsionador está basada en una tabla de búsqueda compleja que permite programar las curvas de conversión inversas de AM-AM y AM-PM de un amplificador de potencia

An overview on RF and microwave research in Latin America: scanning Latin American research on microwaves

We present in this article an up-to-date general and brief scan of the main research activities on RF and microwaves in Latin America. First, we geographically identify the main research and development clusters on RF and microwaves in this large region of the world. We next describe the most recent and representative research work developed in the most active Latin American countries in this technical field; namely, Argentina, Brazil, Chile, Colombia, Costa Rica, Ecuador, Mexico, Peru, and Puerto Rico. To develop this updated survey on RF and microwaves in Latin America, we started from considering previous similar reviews available in the literature [ ],[ ], including some of them focused on specific Latin American countries [ ],[ ]. In our review, we essentially focus on the last five or six years of scientific research production. Given the synergistic relationship between the IEEE MTT-S and the level of activities and maturity in RF and microwaves, we finalize our article by summarizing the status as well as the main challenges and opportunities for MTT-S in Latin America.ITESO, A.C

Advances in Microwave Large-Signal Metrology: From Vector-Receiver Load-Pull to Vector Signal Network Analyzer and Time-Domain Load-Pull Implementations (Invited Paper)

Radiofrequency (RF) power amplifiers (PAs) are important elements of modern communication systems. The most important components in PAs are the transistors, which are operated under large-signal regimes in such applications. Designing and optimizing PAs are challenging tasks that demand the highest accuracy on large-signal measurements at both device and circuit levels. Large-signal power transistor characterization demands the development and utilization of high-frequency and low-frequency load-pull systems. Furthermore, the static and dynamic characterization of two-input PAs requires the development of new measurement systems that consist of an nonlinear vector network analyzer (NVNA) and an arbitrary waveform generators (AWG). This paper reviews the research activities, achievements, and current research goals at CICESE Research Center in Mexico in the large-signal microwave metrology field

Advances in Microwave Large-Signal Metrology: From Vector-Receiver Load-Pull to Vector Signal Network Analyzer and Time-Domain Load-Pull Implementations (Invited Paper)

Radiofrequency (RF) power amplifiers (PAs) are important elements of modern communication systems. The most important components in PAs are the transistors, which are operated under large-signal regimes in such applications. Designing and optimizing PAs are challenging tasks that demand the highest accuracy on large-signal measurements at both device and circuit levels. Large-signal power transistor characterization demands the development and utilization of high-frequency and low-frequency load-pull systems. Furthermore, the static and dynamic characterization of two-input PAs requires the development of new measurement systems that consist of an nonlinear vector network analyzer (NVNA) and an arbitrary waveform generators (AWG). This paper reviews the research activities, achievements, and current research goals at CICESE Research Center in Mexico in the large-signal microwave metrology field

A New Analytical Method to Calculate the Characteristic Impedance ZC

Abstract. A new analytical method to calculate the characteristic impedance of transmission lines embedded in identical, symmetrical and reciprocal connectors is herein presented. To calculate the characteristic impedance of transmission lines, the proposed method uses S-parameter measurements performed on two uniform transmission lines having the same characteristic impedance and propagation constant but different lengths. The method was successfully applied to characterize microstrip lines printed on an FR4 substrate in the 0.45-4GHz frequency range

A digital predistortion technique based on a NARX network to linearize GaN class F power amplifiers

This work presents a novel Digital Predistortion (DPD) scheme based on a NARX network, suitable for linearizing power amplifiers (PAs). The NARX network is a Recurrent Neural Network (RNN) with embedded memory that allows efficient modeling of nonlinear systems. Its neural architecture is very effective to model long term dependencies, such as the typical memory effects of PAs. To demonstrate the feasibility of the NARX network as a DPD system, a GaN class F PA with two LTE signals with 5 MHz of bandwidth is used. Experimental results show a distortion correction better than 10 dB. © 2014 IEEE

Application of the NARX neural network as a digital predistortion technique for linearizing microwave power amplifiers

This work presents a digital predistortion (DPD) scheme to linearize power amplifiers (PAs) using a recurrent neural network called Nonlinear AutoRegressive with eXogenous input model (NARX) neural network (NARXNN). The architecture of the NARXNN is based on a class of discrete-time nonlinear system named NARX. Its topology has embedded memory at the input and output of the neural architecture, which allows an efficient linearization of PAs. To show the benefits of the DPD with NARXNN, a commercial PA is fed with a long term evolution signal at 2.0 GHz with 10 MHz of bandwidth. Our experimental results show an adjacent channel leakage ratio improvement of 24 dB.ITESO, A.C.Cinvestav GuadalajaraCICES