Low Noise Amplifier Design At 2.4 Ghz For WLAN Application.

LOW NOISE AMPLIFIER AT 2.4GHZ FOR WLAN APPLICATION

SITI ADLINA BTE MD ALI

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

SITI ADLINA BTE MD ALI

This report is submitted in partial fulfillment of requirements for the Degree of Bachelor in Electrical Engineering (Telecommunication Electronics)

Faculty of Electronic and Computer Enginnering Universiti Teknikal Malaysia Melaka

“I hereby declare that this report is the result of my own work except for quotes as citied in the references.”

Signature :………

Author : SITI ADLINA BTE MD ALI

“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 honors.”

Signature :………

Supervisor’s Name : MR. ZOINOL ABIDIN BIN ABD AZIZ

ACKNOWLEDGEMENT

Praise the lord the Almighty One for giving me the patience, wisdom and perseverance to complete this project. I would like to take this opportunity to express my gratitude to my supervisor, Mr. Zoinol Abidin Bin Abd Aziz for his patience and guidance in helping me to complete this project.

My special thanks to Mohd Hafizan Che Halim (master student) for his kind suggestions and help during the work. I also thank to the entire BENT 08/09 final years student’s at UTEM who made this thesis work easy and fast.

Last but not least, I would like to take this opportunity to thank to my family esspecially to my husband and also my parents for who supported me morally in any situation during my studies and thesis work.

ABSTRACT

Wireless LAN technology is one of the needed facilities nowadays. The best coverage of Wireless LAN depends on performance of the amplifier inside the receiver block diagram. The demand of the first amplifier is low noise that can minimize the noise level of the received signal. The noise will be attenuation, interference, crosstalk and power adjacent which is added during transmission. The amplifier is known as Low Noise Amplifier (LNA). This project present of the Low Noise Amplifier at 2.4 GHz by using ATF 54143. LNA designed involve three different methods which are maximum gain, low noise and specified gain design methods. All the design was simulate in ADS2006 to perform noise figure, s parameters and stability simulations. Maximum Gain method gives maximum value of gain which is 14.549 dB and noise as 0.54 dB. For Low Noise Amplifier method, it gives the minimum value of noise which is 0.0162 dB while gain as 6.742 dB. While for Specified Gain design method, gain produced is 9.774 dB and noise is 0.5 dB.

ABSTRAK

Teknologi LAN tanpa wayar adalah satu kemudahan yang amat di perlukan sekarang. Liputan LAN tanpa wayar bergantung kepada prestasi penguat di dalam rajah blok penerima. Kepentingan penguat yang utama ialag hingar yang rendah dimana akan merendahkan paras hingar pada signal penerima. Hingar terdiri daripada pengurangan, campuran isyarat, cakap silang dan kuasa bersebelahan dmana hingar ini wujud semasaproses penghantaran. Penguat tersebut dikenali sebagai Low Noise Amplifier (LNA). Projek ini akan mereka Low Noise Amplifier pada 2.4 GHz dengan menggunakan ATF 54143. Rekaan LNA terdiri daripada tiga kaedah yang berlainan iaitu gain yang maksimum, hingar yang minimum dan gain yang ditentukan. Semua kaedah disimulasi menggunakan ADS2006 untuk simulasi hingar, s parameters dan kestabilan. Kaedah gain yang maksimum memberikan gain sebanyak12.549 dB dan hingar sebanyak 0.54 dB. Bagi kaedah hingar yang minimum, gain terhasil sebanyak 6.742 dB manakala hingar terhasil sebanyak 0.0162 dB. Manakala, kaedahgain yang ditentukan, gain dan hingar yang terhasil adalah sebanyak 9.774 dB dan 0.54 dB.

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION DEDICATION

ACKNOWLEDGEMENTS ABSTRACT

ABSTRAK

TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES

LIST OF ABBREVIATION LIST OF APPENDICES

ii iii iv v vi vii ix x xii xiv

1 INTRODUCTION

1.1 Introduction 1.2 Problem Statement 1.3 Objective

1.4 Scope of Project 1.5 Methodology 1 1 3 4 5 6

2 BACKGROUND STUDY

2.1 WLAN Basic 2.2 Standard of WLAN

2.3 Single Stage Transistor Amplifier Design 2.4 Characteristics of Microwave Transistor

7 7 8 10 12

3 THEORY

3.1 Introduction 3.2 DC Biasing

3.3 Stability of Amplifier

14 15 19 19

3.4 Input and Output Matching

3.4.1 Quarter Wave Transformer matching 3.4.2 Single Stub matching

3.5 Planar Transmission Lines 3.5.1 Strip Line

3.5.2 Micro-strip 3.6 Two Port Power Gain

3.6.1.0 Single Stage Transistor Amplifier Design

3.6.1.1 Design for Maximum Gain 3.6.1.2 Low Noise Amplifier Design

3.6.1.2 Constant Gain Circle and Design for Specified Gain

3.6.2.0 Broadband Amplifier Design

3.6.2.1Balanced Amplifier 3.6.2.2 Distributed Amplifier

24 26 28 31 31 32 33 37 38 42 43 45 47 49 4 5

DESIGN LOW NOISE AMPLIFIER 4.1 Transistor Selection

4.2 Project Methodology 4.2.1 Flow Chart

4.2.2 Explanation of Flow Chart 4.3 Transistor Biasing

4.4 Transistor Stability 4.5 Design Process

4.6 Input and Output Matching

RESULT AND DISCUSSION 5.1 Requirements

5.2 Simulation Result

5.2.1 Design for Maximum Gain 5.2.2 Low Noise Amplifier Design

5.2.3 Constant Gain Circle and Design for Specified Gain 51 51 53 53 54 55 57 59 62 64 66 67 68 69

6

5.3 Theory and Simulation Comparison

5.3.1 Input and Output Matching Comparison 5.3.2 Gain and Noise Comparison

CONCLUSIONS

6.1 Discussion and Conclusions 6.2 Future Work

REFERENCE APPENDICES

70 71

71 72

74 75

\

LIST OF TABLE

TABLE TITLE PAGE

1 2 3 4 5 6 7 8 9 10 11

WLAN IEEE 802.11 Standards

Summarizes of Stability Factor at 2.4GHz ATF 54143 Biasing

Gain, Center And Radius Of Input Constant Gain Circle Gain, Center And Radius Of Input Constant Gain Circle Gain, Center And Radius Of Output Constant Gain Circle

Width and Length of Input and Output Impedance Width and Length of Input and Output Impedance Width and Length of Input and Output Impedance Port Matching Comparison

Designs for Maximum Gain Low Noise Amplifier Design

Constant Gain Circle and Design for Specified Gain

8 52 56 61 61 62 63 63 64 71 72

LIST OF FIGURES

FIGURE TITLE PAGE

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Low Noise Amplifier signal Project Methodology Amplifier Classes

The cross section, top view and equivalent circuit of transistors GaAs FETs and Silicon Bipolar

Five Basic Dc Bias Networks Input Stability Circle

Output Stability Circle

Matching With a Single Section Quarter-Wave Transformer

The Quarter-Wave Transformer Solution Single Stub Tuning Circuit

The Single Stub Matching Solution Strip-line Transmission Line Micro-strip transmission line

A Two-Port Networks With General Source and Load Impedances

The General Transistor Amplifier Circuit

A Balanced Amplifier Using 900 Hybrid Couplers Configuration Of An N Stage Distributed Amplifier

2 6 11 13 18 22 22 26 27 28 30 31 32 35 39 47 49

18 19 20 21 22 23 24 25 26 27

General Flow Chart of Designing Low Noise Amplifier ATF 54143 Biasing Circuit

S Parameters of Maximum Gain Amplifier Noise Figure

Noise

S Parameters of Low Noise Amplifier Noise Figure

Noise

S Parameters of Specified Gain Amplifier Noise Figure

Noise

53 55 68 68 68 69 69 69 70 70

LIST OF APPENDICES

INDEX

A B C D E F G

TITLE

Data Sheet of ATF 54143 Stability Circle

Low Noise Amplifier Design

Constant Gain circle and Design for Specified Gain Maximum Gain Design Matching

Low Noise Amplifier Design Matching

Constant Gain circle and design for Specified Gain Matching

PAGE

60 65 66 67 69 71

CHAPTER 1

INTRODUCTION

1.1 Introduction

Over recent years, the interest in microwave techniques for communication systems has grown tremendously and also the development and the performance of microwave active and passive circuits for wireless technologies has become extremely advanced. Microwave amplifiers have become one of the most critical active circuits that employed in the system applications, [1]. Low Noise Amplifies (LNA’s) are found in many applications, especially, LNA’s are used to amplify the received low power signal and separate it from the noise floor, [2]

As a main function block in the RF receiver front-end, a Low Noise Amplifier plays critical role of reducing level of noise present in the signal received at antenna. Signal received at antenna has noise due to attenuation, interference, crosstalk, power adjacent. So, LNA will decrease the noise level so receiver will identify which one is useful signal.

(a) (b)

Figure 1 Low Noise Amplifier signal a) Input of LNA b) Output of LNA

1.2 Problem Statement

In general, received signals at receiver of Wireless LAN antenna contain noise. The medium between transmitter and receiver of Wireless LAN antenna is air, so the possibility of having noise is high. The noises are due to attenuation, interference, crosstalk and power adjacent. Transmission line also contributes to produce noise in the signal. So, received signals at receiver’s antenna will have usable signal adding by noise which cannot be differentiate.

The only solution of this problem is adding Low Noise Amplifier at the first stage of receiver. The main function of LNA is to reduce the noise level present in received signal. Therefore it will gives dominant effect of noise on overall system. To select an appropriate amplifier, first understand the noise parameters for a particular application and then determined whether an amplifier is indeed low noise [3].

1.3 Objectives

The objectives of this Low Noise Amplifier design are to design and simulate Low Noise Amplifier circuit for WLAN application. The design, simulate and measure steps will considers stability, gain and noise figure parameters. While the design process will be done by calculates related parameters by using ideal microwave amplifier equations.

1.4 Scope of Work

The scope of work for this project can be divided into four parts which are: • The first part is designing Low Noise Amplifier by using ATF 54143 – It

involves selection of proper transistor, checking the transistor stability and calculates the gain and noise figure parameters by using maximum gain method. All the parameters will be calculated by using ideal microwave amplifier equations.

• The second part is simulation by using Advanced Design System (ADS2006) to make sure the results are close to the calculated design parameters.

These two steps will be used to design Single Stage Low Noise Amplifier with three different methods which are Design for Maximum Gain, Low Noise Amplifier Design and Design for Specified Gain

1.5 Methodology

The first step of this project is review the background of designing Low Noise Amplifier and the application in Wireless LAN system. Reviewing of LNA done by find all journals, articles, books, and website which are related. Most of the journals and articles are referring to Institute of Electrical and

Electronics Engineers (IEEE) website.

Then, the second step is design process which done by calculate stability, gain and noise figure of the ATF 54143 transistor at 2.4 GHz by using maximum gain method. The parameters calculation will refer to ideal microwave amplifier equations.

The third step is simulation process that done by using Advance Design System (ADS). Before start the simulation, the study of the ADS software is done. The simulation will consider stability, gain and noise figure of the ATF 54143 transistor at 2.4 GHz. All the simulation parameters will more less same to calculated parameters.

All the third steps will be used to design Single Stage Low Noise Amplifier with three different methods which are Design for Maximum Gain, Low Noise Amplifier Design and Design for Specified Gain

Literature Review Design Process

Simulation

CHAPTER 2

BACKGROUND STUDY

2.1 Introduction to WLAN Basics

New communication systems operate in the frequency range 1-100 GHz; third generation mobile phone telephony utilizes the frequency band 1.9-2.2 GHz, wireless local area networks (WLAN’s) operate at the frequency band 2.4-5 GHz and automobile radar system work at 77 GHz. WLAN’s data communication systems are implemented as an alternative to wired local area. It is the most convenient way to establish high speed Internet and Internet connections and distributes data throughout the area.

.

A Wireless LAN (WLAN) is Wireless Local Area Network which links two or more devices by using Spread Spectrum or Orthogonal Frequency Division Multiplexing (OFDM). This enables communications between devices in a limited area. Users can move around within a broad coverage area and still be connected to the network. The advantages of WLAN are easy installation and location freedom suitable for home user and public business [4].

2.2 Standard of WLAN

The market of Wireless Local Area network (WLAN) is in constant explosion since its appearance in the 90’s. The constant demand on increased speed has pushed the early 802.11 standard. It is also known as WiFi with 2 Mb/s data rate to move 802.11b standard with 11 Mb/s data rate and finally to the 802.11g which reaches 54 Mb/s data rate. Both 802.11b and 802.11g standards are operates at 2.4 GHz. IEEE 802.11 is family of wireless standards [4].

Table 1 WLAN IEEE 802.11 Standard [5]

Protocol 802.11a 802.11b 802.11g

Release Date 1999 1999 2003

Frequency (GHz) 5.15-5.35 5.47-5.725 5.725-5.875

2.4-2.5 2.4-2.5

Max Bandwidth (Mbps) 54 11 54

Range Indoor (m) 25 35 25

Range Outdoor (m) 75 100 75

802.11b works on the frequency of 2.4 GHz with maximum bandwidth of 11 Mbps. 802.11b uses DSSS (Direct-sequence spread spectrum) and CCK (Complementary Code Keying) on the frequency 2.4 to 2.483 GHZ. DSSS is the modulation technique in which transmitted signal takes up more bandwidth than the information signal that is being modulated. Its range in the indoor environment is about 35 meters and 100 meters in outdoor environment.

802.11g was released in June 2003. It works on frequency of 2.4 GHz, but its maximum bandwidth is 54 Mbps. 802.11g uses Orthogonal Frequency-Division Multiplexing (OFDM) for 54, 48, 36, 24, 18, 12, 9, 6 Mbps. For 11 and 5.5 Mbps it uses CCK and DSSS (like 802.11b). Its range in the indoor environment is about 25 meters and 75 meters in outdoor environment.

2.3 Characteristics of Microwave Transistors

Microwave transistors are used as amplifiers, oscillators, switches, phase shifters, mixers and active filters. Most of these applications used either silicon bipolar transistors or GaAs field effect transistors (FETs). Silicon bipolar device technology is very mature and inexpensive compared to GaAs transistor technology. Bipolar transistors are capable of higher gain and power capacity at lower frequencies, but GaAs FETs generally have better noise figures and can operate at much higher frequencies.

Microwave Field Effect transistors can be used at frequencies well into the millimeter wave range with high gain and low noise figure, making them the device of choice for hybrid and monolothic integrated circuits at frequencies above 5 to 10 GHz [5]. In order to operate the transistor, positive Vds is supply to drain port. An input signal voltage on the gate then modulates

majority electron carriers from drain producing voltage amplification. The gate length of the transistor limits the maximum frquency of operation. FET’s have gate lenghts 0.3 to 0.6 µm with upper frequency lomits of 100 to50 GHz.

Microwave bipolar transistors are usually of the NPN type and are often preferred over GaAs FETs at frequencies below 2 to 4 GHz because of the higher gain and lower cost [5]. Noise figure of bipolar transistors is not good as FETs because bipolar transistors are subject to shot noise as well as thermal noise effects. Figure 3 summarizes the cross section, top view and equivalent circuit of transistors GaAs FETs and Silicon Bipolar.

Transistor GaAs FET Silicon Bipolar Transistor Cross

Section of Transistor

Top View of Transistor

Equivalent Circuit

Common Source Configuration

Ri (series resistance) = 75Ω Rds (drain to source resistance) = 40Ω

Cgs (gate to source capacitance) = 0.3pF

Cds (drain to source capacitance) = 0.12pF

Cgd (gate to drain capacitance) = 0.01pF

gm (transconductance) = 40ms

Common Emitter Configuration

Rb (base resistance) = 7 Ω R_π (equivalent π resistance) = 110 Ω

Cπ (equivalent π capacitance)

= 18 pF

Cc (collector capacitance) = 18 pF

gm (transconductance) = 900ms

Figure 3 The cross section, top view and equivalent circuit of transistors GaAs FETs and Silicon Bipolar. [5]

2.4 Single Stage Transistor Amplifier

Basically, amplifier is devices that will be used to amplify the receive signal to the appropriate amplitude correspond to the transistor’s gain. Amplifier distribute into two groups which are Radio Frequency (RF) amplifier and analog amplifier. The RF amplifier will be used for high frequency while analog amplifier will be used for low frequency. Power Amplifier and Low Noise Amplifier are a part of RF amplifier while Audio Amplifier and Optical Amplifier are a part of Analog Amplifier.

1.5 Methodology

The first step of this project is review the background of designing Low Noise Amplifier and the application in Wireless LAN system. Reviewing of LNA done by find all journals, articles, books, and website which are related. Most of the journals and articles are referring to Institute of Electrical and Electronics Engineers (IEEE) website.

Then, the second step is design process which done by calculate stability, gain and noise figure of the ATF 54143 transistor at 2.4 GHz by using maximum gain method. The parameters calculation will refer to ideal microwave amplifier equations.

The third step is simulation process that done by using Advance Design System (ADS). Before start the simulation, the study of the ADS software is done. The simulation will consider stability, gain and noise figure of the ATF 54143 transistor at 2.4 GHz. All the simulation parameters will more less same to calculated parameters.

All the third steps will be used to design Single Stage Low Noise Amplifier with three different methods which are Design for Maximum Gain, Low Noise Amplifier Design and Design for Specified Gain

Literature Review Design Process

Simulation

CHAPTER 2

BACKGROUND STUDY

2.1 Introduction to WLAN Basics

New communication systems operate in the frequency range 1-100 GHz; third generation mobile phone telephony utilizes the frequency band 1.9-2.2 GHz, wireless local area networks (WLAN’s) operate at the frequency band 2.4-5 GHz and automobile radar system work at 77 GHz. WLAN’s data communication systems are implemented as an alternative to wired local area. It is the most convenient way to establish high speed Internet and Internet connections and distributes data throughout the area.

.

A Wireless LAN (WLAN) is Wireless Local Area Network which links two or more devices by using Spread Spectrum or Orthogonal Frequency Division Multiplexing (OFDM). This enables communications between devices in a limited area. Users can move around within a broad coverage area and still be connected to the network. The advantages of WLAN are easy installation and location freedom suitable for home user and public business [4].

2.2 Standard of WLAN

The market of Wireless Local Area network (WLAN) is in constant explosion since its appearance in the 90’s. The constant demand on increased speed has pushed the early 802.11 standard. It is also known as WiFi with 2 Mb/s data rate to move 802.11b standard with 11 Mb/s data rate and finally to the 802.11g which reaches 54 Mb/s data rate. Both 802.11b and 802.11g standards are operates at 2.4 GHz. IEEE 802.11 is family of wireless standards [4].

Table 1 WLAN IEEE 802.11 Standard [5]

Protocol 802.11a 802.11b 802.11g

Release Date 1999 1999 2003

Frequency (GHz) 5.15-5.35 5.47-5.725 5.725-5.875

2.4-2.5 2.4-2.5

Max Bandwidth (Mbps) 54 11 54

Range Indoor (m) 25 35 25

Range Outdoor (m) 75 100 75

802.11b works on the frequency of 2.4 GHz with maximum bandwidth of 11 Mbps. 802.11b uses DSSS (Direct-sequence spread spectrum) and CCK (Complementary Code Keying) on the frequency 2.4 to 2.483 GHZ. DSSS is the modulation technique in which transmitted signal takes up more bandwidth than the information signal that is being modulated. Its range in the indoor environment is about 35 meters and 100 meters in outdoor environment.

802.11g was released in June 2003. It works on frequency of 2.4 GHz, but its maximum bandwidth is 54 Mbps. 802.11g uses Orthogonal Frequency-Division Multiplexing (OFDM) for 54, 48, 36, 24, 18, 12, 9, 6 Mbps. For 11 and 5.5 Mbps it uses CCK and DSSS (like 802.11b). Its range in the indoor environment is about 25 meters and 75 meters in outdoor environment.

2.3 Characteristics of Microwave Transistors

Microwave transistors are used as amplifiers, oscillators, switches, phase shifters, mixers and active filters. Most of these applications used either silicon bipolar transistors or GaAs field effect transistors (FETs). Silicon bipolar device technology is very mature and inexpensive compared to GaAs transistor technology. Bipolar transistors are capable of higher gain and power capacity at lower frequencies, but GaAs FETs generally have better noise figures and can operate at much higher frequencies.

Microwave Field Effect transistors can be used at frequencies well into the millimeter wave range with high gain and low noise figure, making them the device of choice for hybrid and monolothic integrated circuits at frequencies above 5 to 10 GHz [5]. In order to operate the transistor, positive Vds is supply to drain port. An input signal voltage on the gate then modulates majority electron carriers from drain producing voltage amplification. The gate length of the transistor limits the maximum frquency of operation. FET’s have gate lenghts 0.3 to 0.6 µm with upper frequency lomits of 100 to50 GHz.

Microwave bipolar transistors are usually of the NPN type and are often preferred over GaAs FETs at frequencies below 2 to 4 GHz because of the higher gain and lower cost [5]. Noise figure of bipolar transistors is not good as FETs because bipolar transistors are subject to shot noise as well as thermal noise effects. Figure 3 summarizes the cross section, top view and equivalent circuit of transistors GaAs FETs and Silicon Bipolar.

Transistor GaAs FET Silicon Bipolar Transistor Cross

Section of Transistor

Top View of Transistor

Equivalent Circuit

Common Source Configuration

Ri (series resistance) = 75Ω Rds (drain to source resistance)

= 40Ω

Cgs (gate to source capacitance) = 0.3pF

Cds (drain to source capacitance) = 0.12pF

Cgd (gate to drain capacitance) = 0.01pF

gm (transconductance) = 40ms

Common Emitter Configuration

Rb (base resistance) = 7 Ω R_π (equivalent π resistance) =

110 Ω

Cπ (equivalent π capacitance)

= 18 pF

Cc (collector capacitance) = 18 pF

gm (transconductance) = 900ms

Figure 3 The cross section, top view and equivalent circuit of transistors GaAs FETs and Silicon Bipolar. [5]

2.4 Single Stage Transistor Amplifier

Basically, amplifier is devices that will be used to amplify the receive signal to the appropriate amplitude correspond to the transistor’s gain. Amplifier distribute into two groups which are Radio Frequency (RF) amplifier and analog amplifier. The RF amplifier will be used for high frequency while analog amplifier will be used for low frequency. Power Amplifier and Low Noise Amplifier are a part of RF amplifier while Audio Amplifier and Optical Amplifier are a part of Analog Amplifier.