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Design, Modeling and Experimental Characterisation of RF and Microwave Devices and Subsystems

Design, Modeling and Experimental Characterisation of RF and Microwave Devices and Subsystems. Presented by: Abdullah Atalar. OUTLINE. Three areas of Interest Power amplifier nonlinearity and its effects on system performance

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Design, Modeling and Experimental Characterisation of RF and Microwave Devices and Subsystems

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  1. Design, Modeling and ExperimentalCharacterisation of RF and Microwave Devices andSubsystems Presented by: Abdullah Atalar

  2. OUTLINE Three areas of Interest Power amplifier nonlinearity and its effects on system performance Using Real Frequency Technique for wideband matching of RF components Integration of RF IC Front-ends

  3. Power amplifier Nonlinearity and its effects on system performance Chalmers University: Ali Behrevan, Thomas Eriksson Bilkent University: Mustafa Durukal, Hakan Arslan, Gul Safak, Abdulllah Atalar, Tarik Reyhan Polytechnik Torino: Daniel Bustos, Simona Donati, Marco Pirola, Giovanni Ghione

  4. A typical wireless transmitter

  5. Digital baseband predistortion

  6. it++ simulation diagram

  7. Nonlinearity model • AM/AM and AM/PM models • Soft Limiter, RAPP, Saleh, Ghorbani, Rapp and Arctan models • Arctan model: x(t) complex envelope of input, y(t) complex envelope of output.

  8. Power Amplifier TypesSOFT LIMITER

  9. Power Amplifier TypesRAPP

  10. Power Amplifier Types3rd Order Polynomial

  11. Power Amplifier TypesSALEH (AM/AM)

  12. Power Amplifier TypesSALEH (AM/PM)

  13. New amplifier class in it++ Implements nonlinearity models Needs four parameters to represent nonlinearity: Two complex, two real. Parameters are found by curve fitting to measured characteristics.

  14. A new predistorter class in it++

  15. Update algorithm • During the training sequence for every input symbol, the coefficients of the polynomial predistorter are updated according to LMS algorithm using amplitude and phase errors.

  16. Simulation #1: No Band Pass Filter Output of raised cosine filter After predistorter After power amplifier

  17. Simulation #2: With Band Pass Filter Output of raised cosine filter After predistorter +BPF After power amplifier

  18. Baseband Model of a Communication System that uses OFDM

  19. Two Sources of Distortion In The Received Signal • Additive noise channel between the transmitter and receiver sides • Nonlinearity of the power amplifier at the end of the transmitter side

  20. Effect of Noise on the System Performance

  21. Effect of Noise on the System Performance • Figure of merit: Bit Error Rate (BER) • Error rate in a 16-QAM OFDM system with no amplification • SNR (signal to noise ratio) limits the BER of the system • To reduce the effect –>use Convolutional Encoder

  22. Outer-band Outer-band In-band Effect of Nonlinear Power Amplifier on the Transmitted Signal

  23. Base-band Model of a Three Transmitter – Receiver System

  24. Distortions Introduced by the Nonlinear Power Amplifier • In a single transmitter – receiver system • In-band distortion • In a multiple transmitter – receiver system • In-band distortion • Outer-band distortion

  25. Distortions Introduced by the Nonlinear Power Amplifier

  26. Distortions Introduced by the Nonlinear Power Amplifier • Outer-band distortions overlap with and are added to the in-band distortions • Results in degradation in the BER performance • The amount of degradation depends on • Degree of the nonlinearity • Spacing between adjacent channels (Δf)

  27. IBO How far the input is from the saturation region Degree of Nonlinearity • (in simulations) identified by the amplifier parameter IBO (input backoff)

  28. Inputs of the Program • Number of transmitted bits • Encoder type • Base-band modulator • Number of carriers in OFDM • Oversampling factor • Power amplifier type • IBO (input back-off) • SNR (signal to noise ratio) • Channel spacing

  29. Graphical Interface for Link Simulator

  30. In All Simulations • Total number of bits = 106 • No coding • 16 – QAM OFDM • Number of carriers = 1024 • Oversampling factor = 16

  31. Other Inputs • For each amplifier type simulations are done for the following parameters: • IBO (in dB): integer from 0 to 6 • SNR (in dB): integer from 0 to 20 • Channel spacing ÷ 2W = 1 : 0.2 : 3 W is the channel bandwidth of the transmitted signal

  32. Simulation Results

  33. Simulation Results

  34. Simulation Results

  35. Using Real Frequency Technique for wideband matching of RF components Istanbul University: M. Sengul, S. Yarman Techical University of Ilmenau: J. Trabert, Kurt Blau, Matthias Hein, C. Hartmann, J. Weber Uppsala University: Peter Lindberg, Eric Ojefors, Anders Rydberg

  36. Real Frequency Technique An analytical method of matching network design Applicable to components with measured data

  37. 17GHz-23 GHz RF SWITCH Final front-end matching network (top) and back-end matching network (bottom).

  38. (IEEE ISCAS 2006, Kos, Greece, May 21-24, 2006) Transducer power gain of the matched switch

  39. Matching Network Design for a Dual Band PIFA Antenna Layout of antenna

  40. Matching Network Design for a Dual Band PIFA Antenna • The main challenge in terminal antenna design for cellular applications is, due to the limited available volume, obtaining sufficient bandwidth, at multiple frequency bands, without loss of radiation efficiency.

  41. Matching Network Design for a Dual Band PIFA Antenna • A complex matching network synthesized using the simplified real frequency technique, to study the real achievable bandwidth of a dual band PIFA antenna.

  42. Double Band PIFA Antenna Matching Network Final matching network

  43. Double Band Antenna824-960 and 1710-1990 MHz

  44. Measured Results

  45. Matching Network Design for a Dual Band PIFA Antenna • Simulated and measured results indicate • the possibility of extending the useable • operating frequency band of a GSM900/1800 • antenna to quad band coverage, i.e. • GSM850/900/1800/1900. Joint article submitted to EuCAP 2006.

  46. Decoupling, matching and beam forming network port 1 port 2 port n Other possible applications for Real Frequency Technique • Approach • Investigate port-isolations and their impedances • Optimize radiating elements and port parameters • Optimize beam forming and bandwidth (superdirective feed) • Final design of antenna array and decoupling network (e.g. hybrid-integrated module)

  47. Integration of RF IC Front-ends University of Pisa: D. Zito, B. Zeri, L. Fanucci Technical University of Ilmenau: Kurt Blau, Matthias Hein Uppsala University: Peter Lindberg, Eric Ojefors, Anders Rydberg

  48. f0 RX LNA Demodulator Modulator PA TX Single Silicon Die Typical RF Front-end Image Reject Filter TX/RX Antenna Switch

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