OPTIMIZATION OF 5.8 GHz FRONT END RECEIVERS

FOR WiMAX APPLICATION

MUZAFFAR BIN MUSTAFFA

This report is submitted in partial of the requirement for the award of Bachelor of

Electronic Engineering (Telecommunication Electronics) With Honours

Faculty of Electronic and Computer Engineering

Universiti Teknikal Malaysia Melaka

May 2009

ii

UNIVERSTI TEKNIKAL MALAYSIA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN

PROJEK SARJANA MUDA II

Tajuk Projek : OPTIMIZATION OF 5.8 GHz FRONT END RECEIVERS

FOR WiMAX APPLICATION Sesi Pengajian : 2006/2009

Saya MUZAFFAR BIN MUSTAFFA mengaku membenarkan Laporan Projek Sarjana Muda ini disimpan di Perpustakaan dengan syarat-syarat 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) (COP DAN TANDATANGAN PENYELIA)

Alamat Tetap: 12 JALAN SELASIH 15, TAMAN SELASIH 68100 BATU CAVES

SELANGOR

Tarikh: 30 APRIL 2008 Tarikh: 30 APRIL 2008

iii

“I hereby declare that this report is the result of my own work except for quotes as cited

in the reference”

Signature : ………………………………….

Author : MUZAFFAR BIN MUSTAFFA

Date : 30 APRIL 2009

iv

“I hereby declare that I have read this report and in my opinion this report is sufficient in

terms scope and quality for the award of Bachelor of Electronic Engineering (Computer

Engineering) With Honours”

Signature : ……………………………………………

Name : PN ZAITON BINTI ABDUL MUTALIP

Date : 30 APRIL 2009

v

Special dedication to my late father, Mustaffa Bin Nawawi and my mother, Mazanah

Binti Jaafar.

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ACKNOWLEDGEMENTS

I would like to extend my sincere gratitude to my supervisor, Pn Zaiton Binti

Abdul Mutalip, for her assistance and guidance toward the progress of this thesis project.

Through the year, she has been patiently monitoring my progress and guided me in the

right direction and offering encouragement. Obviously the progress I had now will be

uncertain without her assistance. My special appreciation and thank to my friend for their

invaluable assistances towards this thesis project. I also would like to thank to my family

without their support and understanding this would not have been possible.

vii

ABSTRACT

This report explores how to design the Low Noise Amplifier that was used in the

front end receiver for the WiMAX application. This report also explains the

fundamental knowledge in designing the Low Noise Amplifier. The fundamental

objective of this project is to design and optimize the 5.8 GHz front end receiver.

However, the main focus of this project is the designing and optimization of the Low

Noise Amplifier. All the basic parameter and fundamental theory are described in detail.

The result of the design will be revealed and discussed.

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ABSTRAK

Laporan ini mengkaji kaedah untuk mereka-bentuk penguat rendah hingar untuk

pengunaan aplikasi WiMAX. Laporan ini turut menerangkan pengetahuan asas di dalam

kaedah mereka-bentuk penguat rendah hingar. Objektif asas kajian ini adalah untuk

mereka – bentuk penguat rendah hingar dan mengoptima penerima bahagian depan radio

frekuensi. Walau bagaimanapun, laporan ini memfokus pada bahagian mereka-bentuk

penguat rendah hingar. Segala parameter dan teori asas diterangkan secara mendalam.

Hasil projek ini akan didedahkan serta dibincangkan di akhir laporan ini.

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CONTENTS

CHAPTER TITLE PAGES

PROJECT TITLE i

STATUS REPORT FORM ii

STUDENT DECLARATION iii

SUPERVISOR DECLARATION iv

DEDICATION v

ACKNOWLEDGEMENT

vi

ABSTRACT vii

CONTENT ix

LIST OF TABLE xii

LIST OF FIGURE xiii

LIST OF ABBREVIATIONS xv

I INTRODUCTION

1.1 Project Introduction 1

1.2 Objective 2

1.3 Problem Statement 3

1.4 Scope of Work 3

x

1.5 Methodology 4

1.6 Report Structure 4

II LITERATURE REVIEW

2.1 Inroduction to WiMAX 6

2.2 RF Front End Block Diagram 8

2.3 LNA Design 9

2.4 DC Biasing Technique 9

2.5 Stability 11

2.5.1 Consideration for stability in high frequency

amplifier design

11

2.5.2 Stability Decision 11

2.6 Gains 13

2.6.1Two-Port Power Gain

13

2.7 Noise in Amplifiers

17

2.8 Input and Output Matching.

19

2.9 Related Software

20

2.9.1 MathCAD Software

20

2.9.2 Ansoft Designer SV

22

2.9.2.1 Analysis

22

2.9.2.2 Features

23

2.9.3 Agilent Advance Design Systems 23

2.9.4 AWR Microwave Office

24

2.9.5 Software Decision

25

III RESEARCH METHODOLOGY

3.1 Understanding the project 26

3.2 Theoretical and statistical analysis 27

xi

3.2.1 Mathcad Calculation Steps

28

3.3 Simulation of designed amplifier circuit

30

3.3.1 ADS Simulation Steps 30

3.4 Result Discussion 38

IV RESULT ANALYSIS

4.1 Transistor Selection 40

4.2 Analytical Analysis 42

4.2.1 Stability 42

4.2.2 Gain 43

4.2.3 Noise figure 44

4.3 Simulation Analysis 45

4.3.1 Low Noise Amplifier Simulation 45

4.3.2 Front End Receiver Simulation 48

V DISCUSSION AND CONCLUSION

5.1 Discussion

50

5.2 Conclusion

51

5.3 Future Work

52

REFERENCES 53

BIBLIOGRAPHY 55

xii

LIST OF TABLES

TABLE TITLE PAGE

2.1 Comparison Between WiMAX and WLAN 7

2.5.2.1 Decision by formula

11

2.5.2.2 Decision by stability circle

12

xiii

LIST OF FIGURES

FIGURE TITLE PAGE

2.2.1 Front end receiver block diagram 8

2.4.1 Five basic DC bias networks. 10

2.5.1 Output stability circles for conditionally stable device. 12

2.5.2 Example of stability circles 13

2.6.1.1 A two-port network with general source and load

impedances

14

2.8.1 A lossless network matching networks arbitrary load

impedance to

a transmission line 20

2.8.1 Definition symbol 21

2.8.2 Mathematical expression 21

3.2.1.1 Creating new file 28

3.2.1.2 Variable declaration 29

3.2.1.3 Error notification 29

3.2.1.4 Example of complete calculation without error 30

3.3.1.1 Creating new project 31

3.3.1.2 Project view 31

3.3.1.3 Component Group List 32

3.3.1.4 Component Placement 32

3.3.1.5 Component connection using wire 33

3.3.1.6 Tool selection 34

3.3.1.7 Smith Chart Tool 34

xiv

3.3.1.8 Impedance Value 35

3.3.1.9 Example of complete circuit 35

3.3.1.10 Result window 36

3.3.1.11 Data selection in Result 37

3.3.1.12 Example of Result 37

3.1 Project Flow 39

4.1.1 S-parameter provided in the data sheet 41

4.1.2 S-parameter generated using ADS 2005A 41

4.2.1 Stability calculation 42

4.2.2.1 Power Gain calculation 43

4.2.2.2 Available Gain calculation 43

4.2.2.3 Transducer Gain calculation 44

4.2.3.1 Noise Figure calculation 44

4.3.1.1 Complete circuit of Matching Network for the Low

Noise Amplifier

46

4.3.1.2 Output Gain of the Low Noise Amplifier 46

4.3.1.3 Output Gain of the Low Noise Amplifier 47

4.3.1.4 Reflection Coefficients of the Low Noise Amplifier 47

4.3.2.1 Front End Receiver Architecture

48

4.3.2.1 Front End Receiver Output 49

xv

LIST OF ABBREVIATIONS

WiFi - Wireless Fidelity

WiMAX - Worldwide Interoperability Microwave Access

RF - Radio frequency

LNA - Low Noise Amplifier

DC - Direct current

QoS - Quality of Services

VSWR - Voltage Standing Wave Ratio

ADS - Advance Design System

1

CHAPTER 1

INTRODUCTION

Chapter one is focusing on the project background, project’s objectives, problem’s

statements, scope of work, methodology and organization of thesis.

1.1 Project Introduction

Wireless connectivity is very common on these days. The most popular wireless

connectivity for today is Wireless Fidelity (WiFi). WiFi is using the 802.11b and 802.11g

standard which is operated at 2.4GHz. However, this 2.4GHz channel is quite congested. These

channel are not only been used for Wifi but also for Bluetooth, WPAN-CSS (Wireless Personal

Area Network using Chirp Spread Spectrum technique) and ZigBee.

2

However, there are new standard that has been introduced by IEEE which is the 802.16d

and 802.16e. These standards are basically known as WiMax. WiMax are operating at channel of

3.5GHz and 5.8GHz. The 3.5GHz spectrum is a licensed spectrum and the 5.8GHz spectrum is

the unlicensed spectrum.

Front end receiver is the first part of equipment in receiving signal. Basically front end

receiver consists of antenna, Low Noise Amplifier (LNA), Radio Frequency (RF) amplifier,

Power Divider and Band Pass Filter. LNA is an integrated component of most RF systems. In

order to sustain a good signal reception, the total gain of the system should be in big number

while the noise figure should be as low as it could be.

In order to get the best signal, the parameter in the LNA and the RF amplifier can be

manipulate. Theoretically, by improving the gain of the system, the noise figure also will be

increased. The only solution is to find the optimum system in terms of great gain and minimum

noise.

1.2 Objective

The main purpose of this report are to document the learning process involved in the

design and optimize theoretically of LNA that been used in 5.8 GHz operating frequency for the

WiMAX application.

3

The objectives of this LNA design are to understand the concept of WiMAX

communication and RF amplifier system, to know the different between narrow band amplifier

and broadband amplifier, to design a Low Noise Amplifier that can operate in WiMAX

frequency that is 5.8 GHz and finally the design will be simulated by using simulation software

such as Advance System Designer.

1.3 Problem Statement

In general, the Low Noise Amplifier combines reasonable gain, good noise figure and

also stability over entire useful range of frequency. Designing LNA will present challenges in

obtaining high gain, low noise figure, good input and output matching, and the stability over

certain range of frequency. There are certain criteria needs to be look upon during designing

LNA. Those criteria are low supply voltage, low current consumption, high gain, high isolation

and input return loss. Low Noise Amplifier usually implies RF/wireless applications thus the

circuit needs to be small and cheap in order to be used widely. In order to achieve that, the

matching networks can be changed to lump elements for space reduction and cost saving.

1.4 Scope of Work

The scope for this project is to develop and optimize theoretically the LNA and RF

amplifier for the 5.8GHz front end receiver for WiMAX application. This project will only cover

the theoretical analysis which involves the calculation of all the parameters. This project also

will be simulated using simulation software in order to verify the theoretical results. The target of

gain to be achieved is 30dB.

4

1.5 Methodology

The work progress of this project is divided into four main parts:

Understanding the operation of front end receiver, Mathcad, and Advance System

Designer software.

In this part, all the literature review was done. The process included collection of

internet journal, online tutorial and also material collection from printed material.

Theoretical and statistical analysis of LNA using Mathcad.

All the formula was formed in the software which then will be calculated using the

software function itself.

Simulation of designed amplifier circuit using Advance System Designer.

Comparing the theoretical analysis and simulation result.

If problem occur, such as, the theoretical and simulation result doesn’t match, the process will be

repeated from simulation stage

1.6 Report Structure

This report was divided into five chapters. The first chapter is focusing on the

introductions of the project. The introduction consist of the project brief introduction, objective

of the project, the project statement, scope of work, project methodology and the report structure.

5

The second chapter is about the literature review. This chapter is focusing on the

documentation of the theory that related in designing the Low Noise Amplifier. The reviews of

previous case study are also included in this chapter.

The third chapter is mainly about the research methodology. All the progress and work

flow are described in this chapter.

The fourth chapter is about the project progress focusing on the result of the simulation.

All the data that were obtained will be documented in this chapter. The full project results are

shown.

The final chapter is focusing on the discussion and conclusion of this report. These

include the entire result and its justification. Some suggestion on improving this project also will

be discussed.

CHAPTER 2

LITERATURE REVIEW

This chapter reviews some references from previous project, journal, article,

books and data sheet. All these information was collected from the different sources

such as library, internet, product manual and etc. The useful data will be discussed on

the chapter.

2.1 Inroduction to WiMAX

WiMAX is actually the short form of Worldwide Interoperability Microwave

Access. This term is agreed between several companies to be used in general. The actual

name for this standard is IEEE 802.16. [1] This standard is a wireless digital

communication system that is intended for metropolitan area that provides interoperable

broadband wireless connectivity to every person in the metropolitan area. It provides up

7

to 50 kilometers of service area for fixed station, 5 to 15 kilometer for mobile station

allowing user to get broadband connectivity without the need of direct line of sight to the

base station. The WiMAX complaint system will provide a cost effective broadband

access to user at home, in the office, in the areas under-served by wire-line Digital

Subscriber Line (DSL) and cable services and even to users on the move equipped with

portable devides such as laptop and personal digital assistance (PDA).

Table 2.1 Comparison between WiMAX and WLAN

Parameter WiMAX WLAN

Frequency Band 2 to 11 GHz 2.4 GHz

Range 31 miles 100 meters

Data Transfer Rate 70 Mbps 11 Mbps~55 Mbps

Number of user Thousand Dozens

The WiMAX standard relies upon a grant-request access protocol that does not allow

data collision and therefore, uses the available bandwidth more efficiently. No collision

means any loss of bandwidth due to data retransmission. All communication is

coordinate by the base station. The main characteristic of the WiMAX standard include;

Long range of service area – the service area of WiMAX standard can be up to

30 miles.

Higher quality of services – the QoS of WiMAX is definitely higher compare to

other standard due to no collision protocol.

Wireless – WiMAX system is based on the wireless technology therefore the

mobility of new technology can be implemented.

8

2.2 RF Front End Block Diagram

Direct conversion, also known as homodyne or zero-IF conversion, is a natural

approach to convert an RF signal directly to baseband. A baseband signal has all the

frequencies from 0 Hz to the highest frequency component with significant power. After

the frequency it changed for transmission the higher frequency RF signal will have at

least double what the baseband signal had initially. Alternately, one can think of

choosing IF to be zero. The architecture of the proposed project;

Figure 2.2.1 Front end receiver block diagram. [2]

In this project, the part that is being concerned is RF component part or specifically the

low noise amplifier part. The low-noise amplifier (LNA) is a special type of electronic

amplifier or amplifier used in the systems to amplify very weak signals captured by an

antenna. The important things, the LNA deals with noise where LNA remove the noise

even though not totally remove all the signal but it still an important part that dealing

with noise. It just likes reducing the signal noise that came through antenna.

9

2.3 LNA Design

Microwave Transistor Amplifier is design using the scattered parameters (S

parameter). Microwave amplifiers combine active elements with passive transmission

line circuits to provide functions critical to microwave systems and instrument. The

history of microwave amplifiers begins with electrons device using resonant or slow-

wave structures to match wave velocity to electron beam velocity. [3]

The design techniques used for BJT and FET amplifiers employ the full range of

concepts that have been developed in the study of microwave transmission lines, two-

port network and Smith chart presentation. [4]

The development of S-parameter matrix concepts grew from the need to

characterize active devices and amplifiers in a form that recognized the need for

matched termination rather than short-or open circuit termination.

2.4 DC Biasing Technique

DC biasing is an important design consideration for proper operation of

amplifiers [5]. The ideal biasing arrangement should select the proper quiescent point

and hold the quiescent point constant over variation in the transistor parameter and

temperature. This is due to large temperature changed in an active bias network. The DC

and RF circuit should be isolated in order to make sure no RF signal will leak into the

DC biasing circuit and the DC biasing circuit does not disturb the RF performance. In