Abdulrhman M. S. Ahmed
Research skills
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TechnicalPower amplifier design, Characterization, modeling and linearisation using digital Predistorter., Large signal nonlinear measurement, RF/Analog/Microwave board & circuit design and power amplifier design. From CAD and programming point of view, I have experience using different software tools such as ADS (Advanced Design System, Agilent VEE, AWR Microwave Office, CST microwave studio, Printed circuit board design within CR-5000, MATLAB and programming the instruments.
Research experience
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Teaching: High Linear and Efficiency Amplifier Design up to 2.2 GHz. Amplifier Linearisation Techniques like Digital Predistorter. Design of Analog Circuits and Microwave Components. Characterization and Optimization of RF Power Devices Using Harmonic Load/Source Pull Strategies. Nonlinear Measurements
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Teaching: Analysis and Modeling (Dynamic AM/AM
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Teaching: AM/PM
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Teaching: Imps
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Teaching: Memory Effects
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Teaching: ACPR). Working with Simulation Tolls like Agilent ADS
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Teaching: AWR Microwave Office
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Teaching: CST Microwave Studio
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Teaching: Agilent VEE pro and MATLAB. Supervision of Several Final Year Student Master Thesis
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Teaching: Project Works & Seminars. Development and Verification of a Novel Approach for Nonlinearity and Memory Effects Measurements in Power Amplifiers. Nonlinearity Investigation in GaAs
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Teaching: LDMOS and GaN Power Devices. Developing and Verification of a Novel Amplifier Behavioural Models. Teaching and Practical Training in Microwave Integrated Circuits. European and National Projects Leading / Subleading.
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Oct 2003–
Apr 2005Research: High Power Measurement Technique for Characterization and Modeling of GaN Power Device and Power Amplifier with Memory Effects.
University of Kassel · High Frequency & Microwave Engineering · University of KasselBMBF (German Ministry of Research and Technology) in Consortium with IAF (Fraunhofer Institute), FBH (Ferdinand-Braun Institute), Alcatel, and Lucent. Research Program on GaN Electronics · KasselThe Aim of the Project was the Development of a High Power Measurement Techniques for the Characterization and Modeling of GaN Power Devices and Power Amplifiers with Special Focus on Memory Effects. -
May 2002–
Apr 2006Research: TARGET
High Frequency & Microwave EngineeringTop Amplifier Research Groups in a European Team · KasselThe Aim of the Project was: Investigation of Measurement Concepts for the Device Characterization Using Frequency- and Time- Domain Techniques (Dynamic Measurements of AM/AM and AM/PM Characteristics Using Multi-tone or Digitally Modulated Signals); Multi-bias Measurement of Active Power Devices; Development of Different Amplifier Behavioural Modeling Techniques Including Memory Effects. -
Mar 2002–
May 2003Research: Linearisation of Power Amplifier Used in Mobile Application
University of Kassel · High Frequency & Microwave Engineering · University of KasselUniversity of Kassel · KasselThe Aim of the Project was the Development and Verification of Digital Predistortion Linearisation for Basestation Power Amplifiers Used in Universal Mobile Telecommunications System (UMTS).
Education
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Jan 2000–
Mar 2005Kassel University
RF & microwave engineering · Dr.-IngGermany · Kassel
Other
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LanguagesArabic
English
German
Russian -
Other Interests[01] A. Ahmed and G. Kompa: Digital Predistortion Linearization Using Advanced Design System and MATLAB Simultaneously. 11th Conference on Microwaves, Radio Communication and Electromagnetic Compatibility (MIOP), Germany, May 2001, pp. 79 -82.
[02] A. Ahmed, M. Endalkachew, and G. Kompa: Power Amplifier Linearization Using Memory Polynomial Predistorters with Non-uniform Delay Taps. IEEE MTT-S Int. Microwave Symp. Dig. , TX, USA, June 2004, pp. 1871-1874.
[03] A. Ahmed, M. O. Abdalla, E. S. Mengistu, and G. Kompa: Power Amplifier Modeling Using Memory Polynomial with Non-uniform Delay Taps. IEEE 34th European Microwave Conf. Proc., Amsterdam, Oct. 2004, pp. 1457-1460.
[04] A. Ahmed, B. Bunz, M. Gamal-El Din, and G. Kompa: Measurement Set-ups for Memory Effects Characterization in GaN HEMT Power Device. Top Amplifier Research Groups in a European Team (TARGET) Tutorial on Device Characterisation, Amsterdam, October 2004.
[05] A. Ahmed and G. Kompa: PAs in Combined Systems and T/R Modules, System Perspective: PA Characterization and Modelling Approaches. Top Amplifier Research Groups in a European Team (TARGET) Tutorial on Power Amplifier Design, Rome, November 2004.
[06] A. Ahmed, E. R. Srinidhi, and G. Kompa: Efficient PA Modeling Using Neural Network and Measurement Set-up for Memory Effect Characterization in the Power Device. IEEE MTT-S Int. Microwave Symp. Dig. , CA, USA, June 2005.
[07] A. Ahmed, E. R. Srinidhi, and G. Kompa: Comparison Between Memory Polynomial and Neural Network Models for PA Modeling. Top Amplifier Research Groups in a European Team (TARGET) Workshop on RF Power Amplifier, Italy, April 2005.
[08] A. Ahmed, E. R. Srinidhi, and G. Kompa: Envelope Frequency Dependent TDNN Power Amplifier Model. Top Amplifier Research Groups in a European Team (TARGET) Tutorial on Transmitter Design, Athens, September 2005.
[09] A. Ahmed, E. R. Srinidhi, and G. Kompa: Power Amplifier Behavioral Modeling Strategies Using Neural Network and Memory Polynomial Models. Microwave Review Journal- Vol. 12, No.1, June 2006, pp. 15-20.
[10] A. Ahmed, E. R. Srinidhi, and G. Kompa: Neural Network and Memory Polynomial Methodologies for PA Modeling. 7th International Conf. On Telecommunications in Modern Satellite (TELSIKS05), pp. 393-396, Serbia, September 2005.
[11] A. Ahmed: Analysis, Modelling and Linearization of Nonlinearity and Memory Effects in Power Amplifiers Used for Microwave and Mobile Communications. PhD. Dissertation, ISBN 3-89958-146-6, University of Kassel, June 2005.
[12] B. Bunz, Ahmed Abdulrhman, G. Kompa: Influence of Envelope Impedance Termination on RF Behaviour of GaN HEMT. 35th European Microwave Conf. Proc., pp. 1595-1598, Paris, October 2005.
[13] A. Ahmed, B. Bunz, E. R. Srinidhi, and G. Kompa: Effect of the Short Envelope Termination on the Measured Memory Effect in GaN HEMT Power Device. IEEE Topical Workshop on Power Amplifiers for Wireless Communications. CA, USA, January 2006.
[14] A. Ahmed, B. Bunz, E. R. Srinidhi, and G. Kompa: Measurements of Envelope Frequency Dependent Nonlinearity in GaN HEMT Power Device. International Nonlinear Microwave and Millimeter-wave Integrated Circuits (INMmiC) Workshop. Aveiro, Portugal, Jan. 2006.
[15] B. Bunz, A. Z.Markos, A. Ahmed, G. Kompa: Linearisation of high PA with optimised zone 0 terminations. German Microwave Conference, Germany, March 2006.
[16] Ahmed, A: Satellite Systems of Aircraft Navigation & Landing. National Aviation University of Ukraine, February 1997.
Publications
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Measurement Set-Up for Memory Analysis
Year: 12/2006
The present invention is for a measurement process and set-up to analyse memory effects for the modelling of power amplifiers. Unlike GSM driven mobile radio systems with frequency bandwidths of 200 kHz, broadband systems with frequency bandwiths in the MHz area will be used increasingly in future. ... [more] The present invention is for a measurement process and set-up to analyse memory effects for the modelling of power amplifiers. Unlike GSM driven mobile radio systems with frequency bandwidths of 200 kHz, broadband systems with frequency bandwiths in the MHz area will be used increasingly in future. A current example is the UMTS standard with a carrier frequency bandwidth of 5MHz. There are already plans for multi-carrier systems with frequency bandwidths on altogether 60 MHz . For these new radio applications measurement processes are required which are able to deliver measurement data of the type relevant to the design of broadband microwave power amplifiers.
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Power Amplifier Behavioral Modeling Strategies Using Neural Network and Memory Polynomial Models.
Microwave Review Journal-. 06/2006;
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Measuring Device For Analysis of Memory Effects In Electronic Components.
Ref. No: WO/2006/039913
Year: 04/2006
The invention relates to a measuring device for analysis of memory effects in non-linear electronic components or modules (10, 20), characterised in that the components or modules (10, 20) are controlled via the input with a two-tone signal of varying amplitude and varying frequency separation, wher... [more] The invention relates to a measuring device for analysis of memory effects in non-linear electronic components or modules (10, 20), characterised in that the components or modules (10, 20) are controlled via the input with a two-tone signal of varying amplitude and varying frequency separation, whereby said two-tone signal is introduced to the reference channel as reference signal and the distorted output signal from the components or modules (10, 20) is introduced to the measuring channel of the signal analyzer (14, 17) as a signal for measuring, which downmixes the high frequency received signals to an intermediate frequency and carries out an analogue to digital conversion, a rapid Fourier transform (FFT) of the signals at the input and output is carried out by a computer unit (19) and by comparison of the complex supectra thus obtained a complex signal supectrum (Amplitude, Phase) is generated, containing significant information about the given memory properties of the components or modules (10, 20). (FR): L'invention concerne un disupositif de mesure pour l'analyse d'effets mémoire dans des composants ou modules électroniques non linéaires (10, 20). L'invention se caractérise en ce que les composants ou modules (10, 20) sont excités côté entrée avec un signal à double tonalité de différente amplitude et à différent écartement de fréquences, ce signal à double tonalité étant acheminé, en tant que signal de référence, au canal de référence et le signal de sortie des composants ou modules (10, 20), affecté de distorsion, étant acheminé, en tant que signal de mesure, au canal de mesure d'un analyseur de signaux (14, 17), qui abaisse à une fréquence intermédiaire les signaux de réception à haute fréquence et occasionne une conversion analogique-numérique ; une transformation de Fourier rapide (TFR) des signaux aux entrée et sortie est effectuée au moyen d'une unité de calcul (19) et un supectre de signaux complexe (amplitude, phase) est produit par comparaison des supectres complexes obtenus, lequel supectre de signaux contient des informations significatives sur les propriétés de mémoire des composants ou modules (10, 20) données. (DE): Messeinrichtung zur Analyse von Memory-Effekten in nichtlinearen elektronischen Bauelementen oder Baugruppen (10, 20) dadurch gekennzeichnet, dass die Bauelemente oder Baugruppen (10, 20) eingangsseitig mit einem Zwei-Ton-Signal unterschiedlicher Amplitude und unterschiedlichem Frequenzabstand angesteuert werden, wobei dieser Zwei-Ton-Signal als Referenzsignal dem Referenzkanal und das verzerrte Ausgangssignal der Bauelemente bzw. Baugruppen (10, 20) als Messsignal dem Messkanal eines Signalanalysators (14, 17) zugeführt wird, der die hochfrequenten Empfangssignale auf eine Zwischenfrequenz heruntermischt und eine analog-digitale Umwandlung herbeifuhrt, dass mittels einer Recheneinheit (19) eine schnelle Fourier-Transformation (FFT) der Signale am Ein- und Ausgang durchgeführt wird und dass durch Vergleich der dabei gewonnenen komplexen Spektren ein komplexes Signalsupektrum (Amplitude, Phase) erzeugt wird, dass signifikante Informationen über die gegebenen Memory-Eigenschaften der Bauelemente bzw. Baugruppen (10, 20) enthält.
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Linearisation of high PA with optimised zone 0 terminations.
German Microwave Conference,, Germany; 03/2006
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Measurements of Envelope Frequency Dependent Nonlinearity in GaN HEMT Power Device.
International Nonlinear Microwave and Millimeter-wave Integrated Circuits (INMmiC) Workshop., Aveiro, Portugal; 01/2006
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Effect of the Short Envelope Termination on the Measured Memory Effect in GaN HEMT Power Device.
IEEE Topical Workshop on Power Amplifiers for Wireless Communications., CA, USA; 01/2006
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Influence of Envelope Impedance Termination on RF Behaviour of GaN HEMT.
35th European Microwave Conf. Proc., Paris; 10/2005
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Neural Network and Memory Polynomial Methodologies for PA Modeling.
7th International Conf. On Telecommunications in Modern Satellite (TELSIKS05), Serbia; 09/2005
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Envelope Frequency Dependent TDNN Power Amplifier Model.
Top Amplifier Research Groups in a European Team (TARGET) Tutorial on Transmitter Design., Athens; 09/2005
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Efficient PA Modeling Using Neural Network and Measurement Set-up for Memory Effect Characterization in the Power Device.
IEEE MTT-S Int. Microwave Symp. Dig., CA, USA; 06/2005
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Comparison Between Memory Polynomial and Neural Network Models for PA Modeling.
Top Amplifier Research Groups in a European Team (TARGET) Workshop on RF Power Amplifier., Italy; 04/2005
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PAs in Combined Systems and T/R Modules, System Perspective: PA Characterization and Modelling Approaches.
Top Amplifier Research Groups in a European Team (TARGET) Tutorial on Power Amplifier Design, italy; 11/2004
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Power Amplifier Modeling Using Memory Polynomial with Non-uniform Delay Taps.
IEEE 34th European Microwave Conf. Proc., Amsterdam; 10/2004
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Measurement Set-ups for Memory Effects Characterization in GaN HEMT Power Device.
Top Amplifier Research Groups in a European Team (TARGET) Tutorial on Device Characterisation,, October 2004., Amsterdam; 10/2004
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Power Amplifier Linearization Using Memory Polynomial Predistorters with Non-uniform Delay Taps.
IEEE MTT-S Int. Microwave Symp. Dig. , TX, USA, June 2004, pp. 1871-1874. 06/2004;
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Power Amplifier Linearization Using Memory Polynomial Predistorters with Non-uniform Delay Taps.
IEEE MTT-S Int. Microwave Symp. Dig., TX, USA; 06/2004
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Digital Predistortion Linearization Using Advanced Design System and MATLAB Simultaneously.
11th Conference on Microwaves, Radio Communication and Electromagnetic Compatibility (MIOP), Germany; 05/2001
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Satellite Systems of Aircraft Navigation & Landing.
02/1997
Degree: Graduate Engineer (Dipl.-Ing.) Degree Thesis