i DESIGN POWER AMPLIFIER FOR GPS APPLICATION SURIANI BINTI MD NAYAN This Report is Submitted in Partial Fulfillment of Requirements for the Bachelor Degree of Electronic Engineering (Telecommunication Electronics) Faculty of Electronic and Computer Engineering Universiti Teknikal Malaysia Melaka April 2011 ii UNIVERSTI TEKNIKAL MALAYSIA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA II Tajuk Projek : Sesi Pengajian : Saya DESIGN POWER AMPLIFIER FOR GPS APPLICATION BASE ON S-PARAMETER 1 0 / 1 1 SURIANI BINTI MD NAYAN mengaku membenarkan Laporan Projek Sarjana Muda ini disimpan di Perpustakaan dengan syaratsyarat kegunaan seperti berikut: 1. Laporan adalah hakmilik Universiti Teknikal Malaysia Melaka. 2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan laporan ini sebagai bahan pertukaran antara institusi pengajian tinggi. 4. Sila tandakan ( √ ) : SULIT* *(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972) TERHAD** **(Mengandungi maklumat terhad yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan) TIDAK TERHAD Disahkan oleh: __________________________ (TANDATANGAN PENULIS) Tarikh: 21 APRIL 2011 ___________________________________ (COP DAN TANDATANGAN PENYELIA) Tarikh: 21 APRIL 2011 iii “I hereby declare that this report is the result of my own work except for quotes as cited in the references “ Signature :…………………………………………… Author : SURIANI BINTI MD NAYAN Date : 21 APRIL 2011 iv “I hereby declare that I have read this report and in my opinion this report is sufficient in terms of the scope and quality for the award of Bachelor of Electronic Engineering ( Telecommunication Electronics) with Honours.” : Signature :…………………………………………… Supervisor Name : Date : 21 APRIL 2011 v ACKNOWLEDGEMENT I wish to express sincere, heartfelt appreciation to those involved in the completion of this project. First and foremost, I wish to express special thanks, appreciation and deep gratitude t my project supervisor, Encik Azahari bin Salleh, who has been there to provide continuous guidance, advice, encouragement, support and generous amount of time in helping me to complete this project. His remarkable unique ways and professionalism of handling my weaknesses has turned my simplistic mind to see think in more rational and critical view. It has been a great pleasure and privilege tp learn from someone who is professional like him. Sincere appreciation of course goes to my friends who give me unselfish support and special thanks to my parents, Md Nayan bin Md Isa and my mother Zauyah binti Mat Isa because always support me. Above all, I would like to offer my deepest appreciation and thanks giving to Allah S.W.T. There is ni way to measure what You’ve worth. You are The One who has made things possible. You deserve all glory and honor. vi ABSTRACT This thesis is analyzing the Power Amplifier for GPS Application. The power amplifier is in the transmitting chain of the GPS system. They are the final amplification stage before the signal is transmitted. Its must produced enough output power to overcome channel losses between the transmitter and receiver signal gain. The ultimate goal is to design a Power Amplifier which covers range of GPS L1 frequency at 1.575 GHz. The design will focus on designing of matching network base on three difference types of matching network which is single stub element, quarter-wave element and lumped element. Matching is important because to maximize power delivery and minimize power loss and to improve signal to noise ratio as in sensitive components. This power amplifier design is to achieve high power output, gain, noise figure, and insertion loss through the GPS frequency range. The stability analysis of power amplifier is one of the most critical and the most challenging aspects of power amplifier design. This work shows an analysis technique, which accurately predicts the oscillations in power amplifier. Using the technique, different matching techniques and circuits are design and implementation. The transistor was choosing is NPN Bipolar power transistor (AT-41533). The frequency for AT-41533 power transistor is up to 5 GHz. The power amplifier is design based on simulation using AWR Software and the output gain is 15.921 dB using single stub element, 15.13 dB by using quarter wave element and 14.953 dB by using lumped element. From the analysis, we know that single stub element is the good impedance matching because it can fulfill the requirement parameter of the GPS application. vii ABSTRAK Tesis ini menganalisis Penguat Kuasa untuk Aplikasi Sistem Kedudukan Global (GPS). Penguat kuasa dalam rantai penghantaran dari Sistem Kedudukan Global. Ia adalah tahap amplifikasi terakhir sebelum isyarat ini dihantar kepada penerima. Kuasa keluaran yang dihasilkan perlu cukup untuk mengatasi kerugian saluran antara pemancar dan penerima isyarat keuntungan. Tujuan utamanya adalah untuk mereka bentuk sebuah Penguat Kuasa yang merangkumi frekuensi L1 GPS di 1.575 GHz. Rekaan akan fokus pada perancangan yang sesuai pangkalan rangkaian pada tiga jenis perbezaan rangkaian pencocokan yang tunas elemen tunggal, unsur suku gelombang dan elemen lumped. Pencocokan ini penting kerana untuk memaksimumkan penghantaran kuasa dan meminimumkan kerugian daya dan untuk meningkatkan nisbah isyarat terhadap hingar seperti dalam komponen-komponen sensitif. Rekaan power amplifier ini adalah untuk mencapai keluaran yang tinggi, gain, noise figure, dan insertion loss melalui julat frekuensi GPS. Analisis kestabilan power amplifier adalah salah satu yang paling kritikal dan aspek yang paling mencabar dari mereka bentuk power amplifier. Karya ini menunjukkan sebuah teknik analisis yang tepat memprediksi ayunan di power amplifier. Dengan menggunakan teknik ini, teknik pencocokan yang berbeza dan litar adalah rekaan dan pelaksanaan. Transistor yang dipilih adalah Bipolar NPN transistor kuasa (AT-41533). Frekuensi untuk AT-41533 transistor kuasa hingga 5 GHz. Penguat kuasa rekaan berdasarkan simulasi menggunakan perisian AWR ialah 15,921 dB gain keluaran menggunakan elemen stub tunggal, 15.13 dB dengan menggunakan elemen gelombang suku dan 14.953 dB dengan menggunakan elemen lumped. Dari analisis, kita tahu bahawa elemen tunas tunggal adalah pencocokan impedansi baik kerana dapat memenuhi keperluan parameter dari aplikasi GPS. viii CONTENTS CHAPTER I II TOPIC PAGES INTRODUCTION 1.1 Project Background 1 1.2 Objective 2 1.3 Problem Statement 2 1.4 Project Scope 3 1.5 Thesis Outline 3 GLOBAL POSITIONING SYSTEM 2.1 Global Positioning System (GPS) 5 2.2 GPS Orbits 6 2.3 GPS Signals 6 2.4 L1 Carrier Frequency 7 2.5 Demodulation and Decoding 8 2.6 Application of GPS 10 2.6.1 Roads and highway 10 2.6.2 Space 12 2.6.3 Rails 13 2.6.4 Aviation 14 2.6.5 Marine 15 2.6.6 Agriculture 15 ix III AMPLIFIER DESIGN 3.1 Power Amplifier 17 3.1.1 Efficiency 18 3.1.2 Power Gain/ Voltage Gain 18 3.1.3 Linearity 19 3.1.4 1-dB compression 19 3.1.5 Power Consumption 20 3.1.6 Noise Figure 20 Class of Amplifier 20 3.2.1 Class A operations 21 3.3 Single Stage Amplifier 22 3.4 Scattering Parameters 23 3.5 Two-port Scattering Parameters 24 3.6 Relationship with voltage and current 25 3.7 Meanings of s-parameters 25 3.8 Gain Definitions in Power Amplifier 26 3.9 Transducer Power Gain of Two-Port Circuit 27 3.10 Stability of Amplifier 29 3.10.1 Conditions for Stability 29 DC Biasing 31 3.2 3.11 IV PROJECT METHODOLOGY 4.1 Project Expectation Work Flow 33 4.2 Stability 35 4.3 Matching 36 4 .3.1 Lumped Element 38 4.3.2 Single Stub Element 40 4.3.3 Quarter-wave Element 44 x V RESULT AND DISCUSSION 5.1 Selection of transistor 47 5.2 Calculation 49 5.3 Stability Consideration 54 5.4 IV Curve 55 5.5 DC Biasing Simulation Result 56 5.6 Matching Simulation Result 57 5.7 Type of input and output matching 57 5.7.1 Single Stub Matching Network 57 5.7.2 Quarter Wave Matching Network 58 5.7.3 Lumped Element Matching Network 58 S-Parameter Results 59 5.8.1 S21 Output Graft 59 5.8.2 Input Return Loss 60 5.8.3 Output Return Loss 62 5.8.4 Insertion Loss 63 5.8.5 Available Gain 64 5.8.6 Maximum Available Gain 65 5.8.7 Maximum Stable Gain 66 5.8.8 Power Gain 66 5.8.9 Transducer Gain 67 5.8.10 Current Gain 68 5.8.11 Noise Figure 71 Discussion 72 5.8 5.9 VI CONCLUSION AND RECOMMENDATION 6.1 Conclusion 73 6.2 Future Work 74 xi LIST OF FIGURES FIGURE TITLE PAGES Figure 1.1 Power Amplifier on GPS System 2 Figure 2.1 NAVSTAR GPS System Segments 6 Figure 2.2 GPS Signal Code and Carrier Frequency 7 Figure 2.3 GPS Satellite Transmission 8 Figure 2.4 Satellite Signals 9 Figure 2.5 Road and Highway 11 Figure 2.6 Space Application 12 Figure 2.7 Rail Application 13 Figure 2.8 Aviation Application 14 Figure 2.9 Marine Application 15 Figure 2.10 Agriculture Application 15 Figure 2.11 1-dB Compression Characteristics 18 Figure 2.13 General Transistor Amplifier Circuit 22 Figure 3.1 Project Expectation Work Flow 24 Figure 3.2 General Flow Chart of Designing GPS PA 26 Figure 3.3 Termination Matching Network 28 Figure 3.4 Waveguide Matching Network 28 Figure 3.5 Lumped Element Matching Network 30 Figure 3.6 Single Stub Matching Network 30 Figure 3.7 Quarter Wave Element 31 Figure 4.1 Scattering Parameter 34 Figure 4.2 Two-Port Scattering Parameters 35 Figure 4.3 S-parameters 36 xii Figure 4.4 Transducer Power Gain using Z-parameters 37 Figure 4.5 Transducer Power Gain using S-parameters 38 Figure 4.6 Conditions for Stability 39 Figure 4.7 Unconditional Stability 40 Figure 4.8 Conditional Stability 40 Figure 5.1 Parameter define using AWR Software 43 Figure 5.2 S-Paramater define at frequency 1.575 MHz 43 Figure 5.3 Graft of Stability 44 Figure 5.4 Biasing Setup 45 Figure 5.5 IV Curve 45 Figure 5.6 DC Biasing 46 Figure 5.7 Single Stub Matching Network 47 Figure 5.8 Quarter Wave Matching Network 47 Figure 5.9 Lumped Element Matching Network 48 Figure 5.10 S21 Output Graft 49 Figure 5.11 S21 Output Optimization 49 Figure 5.12 Return Loss Input 50 Figure 5.13 Comparison Return Loss Input 51 Figure 5.14 Return Loss Output 51 Figure 5.15 Comparison Return Loss Output 52 Figure 5.16 Insertion Loss 53 Figure 5.17 Comparison Insertion Loss 53 Figure 5.18 Available Gain 54 Figure 5.19 Available Gain after Optimization 54 Figure 5.20 Maximum Available Gain 55 Figure 5.21 Maximum Available Gain after Optimization 55 Figure 5.22 Maximum Stable Gain 56 Figure 5.23 Operating Power Gain 56 Figure 5.24 Operating Power Gain after Optimization 57 Figure 5.25 Transducer Gain 57 Figure 5.26 Transducer Gain after Optimization 58 xiii Figure 5.27 Current Gain at S21 58 Figure 5.28 Current Gain 59 Figure 5.29 Current Gain 59 Figure 5.30 Comparison Voltage Gain VTG 60 Figure 5.31 Voltage Gain VTG 60 Figure 5.32 Comparison Noise Figure 61 Figure 5.33 Comparison Noise Figure Min 61 xiv LIST OF TABLE TABLE TITLE PAGES Table 1.1 Parameters Requirement 4 Table 5.1 Result based on type of Matching 72 xv LIST OF APPENDIXS APPENDIX PAGES APPENDIX A 77 APPENDIX B 80 APPENDIX C 81 APPENDIX D 82 APPENDIX E 83 CHAPTER I INTRODUCTION This chapter will discuss the overview process that involved for this project; the aims and specific objectives of the project, problem statements, work scope, methodology and result. The end of this chapter the thesis outline will be listed. 1.1 Project Background This project implements the Power Amplifier (PA) for Global Positioning System (GPS) system. It’s a software project but lastly must fabricate the result of simulation. Power amplifier is building in satellite transponder on GPS transmission system. Input signal is generally small and needs to be amplified sufficiently to operate an output device. Power Amplifier is design to amplify that signal (RF signal) and provides a large version of the signal that may direct to and antenna. It’s also required to amplify the wanted signal without distortions and without other impairments which would decrease the usefulness of the signal. Power Amplifier is design operating in Class A linear mode over range of 1575.42 MHz. In this project, the transistor was use is the power transistor. Figure 1.1 shows the Power Amplifier on GPS system. 2 Figure 1.1: Power Amplifier on GPS system 1.2 Objective Objective of this project is to design,, simulate and analysis the Power Amplifier for GPS application. Design and analyze matching network base on sparameters for Power Amplifier at L1 Frequency (1575.42 MHz). The power amplifier designed at L1 frequency (1575.42 MHz) for civilian. 1.3 Problem Statement The amplifier is used to increase the signal that drives the signal to the antenna. Without the amplifier, low-power radio-frequency cannot be converting into a large signal of significant power. It’s also can’t optimized to have a high efficiency, high output power compression, good return loss on the input and output, good gain and optimum heat dissipation for driving a signal to the antenna. Signal also has a loss, wanted signal with distortions and other impairments. 3 1.4 Project Scope Scope for this project is analyzing the power amplifier for GPS system at L1 frequency. The frequency is 1575.42MHz. The software that will be use is AWR to simulate the power amplifier. Analyze the power amplifier base on stability, gain, input and output return loss at frequency 1.575 GHz using AWR software. Analyze and comparison on type of matching network base on this element:- (a) Stub element (b) Quarter wave element (c) Lumped element Table 1.1 shows the parameters that been used in this project:- Table 1. 1 Parameters requirement Parameter Requirement Operating frequency 1.575 GHz Gain >10dB Bias Point Transistor 1.5 VVE=2.7V IC=10mA AT-41533 Thesis Outline Chapter 1 is about an introduction of project which includes an explanation of project background, a brief introduction of Global Positioning System (GPS) and Power Amplifier (PA), method used in Power Amplifier design, objectives of project, and project scopes. Chapter 2 of background study defines in detail about GPS and PA , and also about method and type of matching used in the design work. 4 Chapter 3 contains a research methodology which includes the steps to design power amplifier and a brief explanation of methodology flow chart. Chapter 4 contains a details explanation of an amplifier design technique which consist a single stage amplifier design, DC biasing design and input output matching design. Chapter 5 discusses about the selection of transistor and the result from this project, S-parameter analysis, comparison matching network and all gain analysis. Also include the calculation for design. Chapter 6 reveals the conclusion of this project and future works suggestion on this project. 5 CHAPTER II GLOBAL POSITIONING SYSTEM 2.1 Global Positioning System (GPS) The GPS system consists of three pieces. There are the satellites that transmit the position information, there are the ground stations that are used to control the satellites and update the information, and finally there is the receiver that we purchased. It is the receiver that collects data from the satellites and computes its location anywhere in the world based on information it gets from the satellites GPS is part of a satellite-based navigation system developed by the U.S. Department of Defense under its NAVSTAR satellite program. Figure 2.1 shows the NAVSTAR GPS System Segments. Figure 2. 1 NAVSTAR GPS System Segments 6 2.2 GPS Orbits The fully operational GPS includes 24 or more active satellites approximately uniformly dispersed around six circular orbits with four or more satellite each. The orbits are inclined at an angle of 55o relative to the equator and are separated from each other by multiples of 60o right ascension. The orbits are no geostationary and approximately circular, with radii of 26,560km and orbital periods of one half sidereal days. Theoretically, there are more GPS satellite will always be visible from most points on the earth’s surface and four or more GPS satellite can be used to determine an observer’s position anywhere on the earth’s surface 24 hour per day. 2.3 GPS signals Each GPS satellite carries a cesium and/or rubidium atomic clock to provide timing information for the signals transmitted by the satellites. Internal clock correction is provided for each satellite clock. Each GPS satellite transmits two spread spectrum, L-band carrier signal. L1 signal with carrier frequency and an L2 signal with carrier frequency. These two frequencies are integral multiples and of a base frequency . The L1 signal from each satellite uses binary phase-shift keying (BPSK), modulated by two pseudorandom noise (PRN) codes in phase quadrature, designated as the C/A-code and P-code. The L2 signal from each satellite is BPSK modulated by only the P-code. Figure 2.2 shows the GPS signals code and carrier frequencies. 7 Figure 2. 2: GPS signal code and carrier frequencies 2.4 L1 carrier frequency L1 is a civilian-use signal, to be broadcast on the same L1 frequency (1575.42 MHz) that currently contains the C/A signal used by all current GPS users. Figure 2.5 shows the demodulating and decoding signals in GPS system Implementation will provide C/A code to ensure backward compatibility assured of 1.5 dB increases in minimum C/A code power to mitigate any noise floor increase. Non-data signal component contains a pilot carrier to improve tracking enables greater civil interoperability with Galileo L1. Figure 2.4 shows the signal that transmits from satellite. 8 2.5 Demodulation and decoding Figure 2.3 shows demodulating and decoding signal in GPS System. Figure 2. 3: GPS satellite transmissions Figure 2.4 shows the transmission signal from satellite Figure 2. 4: Satellite signals 9 GPS satellites use the microwave L-band to broadcast three separate radionavigation signals on two separate RF channels usually called L1 (around 1.6 GHz) and L2 (around 1.2 GHz). These frequencies were chosen as a compromise between the required satellite transmitter power and ionospheric errors. The influence of the ionosphere decreases with the square of the carrier frequency and is very small above 1 GHz. However, in a precision navigation system it still induces a position error of about 50m at the L1 frequency during daylight and medium solar activity. On the other hand, GPS were designed to work with omnidirectional, hemisphericalcoverage receiving antennas. The capture area of an antenna with a defined radiation pattern decreases with the square of the operating frequency, so the power of the onboard transmitter has to be increased by the same amount. GPS broadcast two different signals: a Coarse/Acquisition (C/A) signal and Precision (P) signal. The C/A-signal is only transmitted on the higher frequency (L1) while the P-signal is transmitted on two widely-separated RF channels (L1 and L2). Since the frequency dependence of ionospheric errors is known, the absolute error on each carrier frequency can be computed from the measured difference between the two P-transmissions on L1 and L2 carries. The L1 C/A- and P-carriers are in quadrature to enable a single power amplifier to be used for both signals. The L1 and L2 transmitter outputs are combined in a passive network and feed an array of helix antennas. These produce a shaped beam covering the whole visible hemisphere from the GPS orbit with the same signal strength. All three GPS transmissions are continuous, straightforward BPSK modulated carriers. Pulse modulation is not used. The timing information is transmitted in the modulation: the user's receiver measures the time of arrival of a defined bit pattern, which is a known code. If desired, the modulation code phase can be related to the carrier phase in the receiver to produce even more accurate measurements, since both the carrier frequency and the code rate are derived coherently from the same reference frequency on-board the satellite.
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