DEVELOPMENT OF SAMPLING MIXER FOR ULTRA- WIDEBAND APPLICATIONS

DEVELOPMENT OF SAMPLING MIXER FOR ULTRA- WIDEBAND APPLICATIONS

Ezwan Bin Muhamad

Tx 5103.4 E99 2009

Bachelor of Engineering with Honours (Electronics and Computer Engineering)

2009

UN1VERSITI INIALAYSIA SARAWAK

R13a ßORANC PENCESAIIAN STATUSTESIS

. ILI(ILII: Development of Sampling Mixer for Ultra-Wideband Applications

SESI PENGA. IIAN: 2008/2009

Sava E"1. NN'AV BIN MUHAMAD

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This Final Year Project attached here:

Title : Development of Sampling Mixer for Ultra-Wideband Applications

Student Name : Ezwan Bin Muhamad Matric No : 13999

has been read and approved by:

(at 6 (oÖ01

Rohana Sapawi Date

(Supervisor)

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UNIVEkSiTI MAL. yYSLr1 SATcAWAK

DEVELOPMENT OF SAMPLING MIXER FOR ULTRA- WIDEBAND APPLICATIONS

EZWAN BIN MUHAMAD

This project is submitted in partial fulfilment of

The requirements for the degree of Bachelor of Engineering with Honours (Electronics and Computer Engineering)

Faculty of Engineering

UNIVERSITI MALAYSIA SARAWAK

2008/2009

To my beloved family, friends and the one who need it

ACKNOWLEDGEMENT

I would like to express my sincere gratitude and appreciation to my supervisor, Rohana Sapawi for her patience encouragement and best guidance to me in preceding my final year project. My thanks also go to Faculty of Engineering, University Malaysia Sarawak for the facilities and support provided.

Also special thanks to my family and to all my friends for their understanding encouragement and support while I was completing my project.

III

AB S TRAK

Tesis ini ditulis bertujuan untuk membuat kajian tentang CMOS sampel signal

digabungkan bersama LNA yang kurang gangguan untuk diaplikasikan pada

rangkaian jalur lebar. Litar yang dicadangkan ini direka untuk berfungsi pada jalur

lebar berfrekuensi 4GHz dengan menggunakan transistor berteknologi CMOS 0.18

µm. Teknik suis dua peringkat digunakan untuk mencapai penambahan kuasa yang

tinggi, suis yang pantas dan bergangguan rendah. Daripada keputusan yang

diperolehi menunjukan nilai ganguan adalah bersamaan dengan 3dB dan

persampelan frekuensi mampu mencapai sehingga 250MHz dengan menggunakan

voltan 1.8 V. Perisian PSpice digunakan untuk membuat simulasi litar dan

memperolehi keputusan simulasi.

ABSTRACT

This thesis aims to study the design of a low-noise CMOS sampling mixer with integrated switching LNA for ultra-wideband. The proposed circuit is designed to work at a wideband frequency of 4 GHz using CMOS 0.18 µm transistor technologies. A two stage switching technique is implemented to achieve low noise figure, high gain and fast sampling. The obtained results show a noise figure equal to 3 dB and sampling frequency up to 250 MHz with I. 8. V do supply voltage. The simulation and result were obtained by using PSpice software.

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UNIVERSITI

MALAYSIA SA WAK

LIST OF CONTENTS

DEDICATION

ACKNOWLEDGEMENTS ABSTRAK

ABSTRACT

TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES

LIST OF ABBREVIATIONS

Chapter 1 INTRODUCTION 1.1 Introduction 1.2 Project Objective

1.3 Thesis Outline

Chapter 2 LITERATURE REVIEW 2.1 Ultra Wideband

2.1.1 Type of UWB Signals 2.1.2 Time Domain Design

2.1.3 Difficulties in using DSP technology

Page

ii

111

iv

V

V1 ix

X

X11

1 3 4

5

9

11

11

2.1.4 Networking Issues 12

2.1.5 Future Direction 13

2.2 Noise 14

2.2.1 Thermal Noise 14

2.2.2 Shot Noise 16

2.2.3 Contact Noise 17

2.2.4 Popcorn Noise 19

2.2.5 Noise Factor 20

2.3 Mixer Theory 23

2.3.1 Resistive Mixers 23

2.3.2 Active Mixers 25

2.4 Fundamental Considerations 26

2.4.1 Conversion Gain 26

2.4.2 Isolation 27

2.4.3 Linearity 28

2.4.4 Nonlinear and Sampling Mode 31

2.4.5 Passive and Active Mixers 32

2.4.6 Balun 33

2.4.7 CMOS Transistor 35

2.5 Mixer Circuit Examples 37

2.5.1 Diode Double-Balance quad Mixer 37 2.5.2 Double-Balance Switching FET Mixer 39

2.5.3 Double-Balance Gilbert Mixer 40

2.5.4 Sampling Mixer 41

2.5.4.1 Charge Injection 43

vii

2.5.4.2 Clock Feedthrough 2.6 Low Noise Amplifier

2.6.1 CMOS LNA 2.7 Time-varying Source

Chapter 3 METHODOLOGY 3.1 Introduction 3.2 Project Overview 3.3 Design Process

3.4 Sampling Mixer Design 3.5 Switching LNA Design 3.6 VPULSE

3.7 Noise Figure Determination 3.8 Bandwidth Determination 3.9 Simulation

Chapter 4 RESULT AND DISCUSSION 4.1 Introduction

4.2 Measurement Result 4.3 Performance Comparison

Chapter 5 CONCLUSION AND RECOMMENDATIONS 5.1 Conclusion

5.2 Recommendations

44 49 50 52

55 56 57 58 59

61 62 64 65

67 68 75

76 77

REFERENCES 78

LIST OF TABLES

Table Pages

2.1 Summary of FCC restriction on UWB operation 7

2.2 A comparison and summarized between nonlinear mode 31 and sampling mode of a mixers.

2.3 The differentiation between passive mixers and active mixers. 32 3.1 The defined parameters for the sampling mixer with integrated LNA. 65 4.1 Performance comparison of published sampling mixer. 73

IX

LIST OF FIGURES

Figure Pages

2.1 Comparison of the Fractional Bandwidth of a Narrowband 10 and Ultra-wideband communication system.

2.2 Typical gain compression characteristic for non-linear mixer, 29 showing the measurement of the 1 dB compression point.

2.3 IM3 gain compression characteristic, the IM3 intercept point is 30 approximately 10dB above the 1 dB compression point.

2.4 Use of a wire-wound on the output of a push-pull amplifier stage 34 to provide a balanced to unbalanced conversion.

2.5 Cross section of NMOS transistor. 35

2.6 Diode Double-Balance quad mixer. 37

2.7 Double-Balance Switching FET mixer. 39

2.8 Double-Balance Gilbert mixer. 40

2.9 Simplest sample and hold circuit in MOS technology. 42

2.10 Sampling or switching mixer. 45

2.11 Sampling or switching mixer output. 46

2.12 Ideal sample and hold operation output waveform. 47

2.13 (a) Common source stage with resistive load,

(b) conversion of load to current source.

2.14 Resistive tenninations by inductive degeneration.

2.15 Definition for time-varying source VPULSE.

51

52

53

2.16 Definition for the time-varying source VSIN. 54

3.1 The overall project sequence that was followed during the studied. 56

3.2 Design Process guideline. 57

3.3 Schematic of the sampling mixer with integrated switching LNA. 59

3.4 VPULSE 1 parameter. 61

3.5 VPULSE 2 parameter. 61

3.6 The proposed circuit simulated on PSpice. 66

4.1 Simulated noise figure of the sampling mixer. 69

4.2 RF input. 70

4.3 Time domain waveform of first pulse and second pulse. 71

4.4 Drain current of M3. 72

4.5 The sampling mixer output waveform 74

X1

LIST OF ABBREVIATIONS

ADC - Analog to Digital Converter

ASIC - Application Specific Integrated Circuit

Clk - Clock

CMOS - Complementary Metal Oxide Semiconductor

dB - Decibel

dc - Direct Current

DSP - Digital Signal Processing

FCC - Federal Communication Commission

FET - Field Effect Transistor

FPGA - Field Programmable Gate Array

GHz - Giga Hertz

I-UWB - Impulse Ultra Wideband

IC - Integrated Circuit

IF - Intermediate Frequency

lIP3 - Third Order Input Intercept Point

IMD - Intermodulation Distortion

JFET - Junction Field Effect Transistor

L - Length

LNA - Low Noise Amplifier

LO - Local Oscillator

LPI - Low Probability of Intercept

MAC - Medium Access Control

MDS Minimum Discernable Signal

MOS - Metal Oxide Semiconductor MOSFET

- Metal Oxide Semiconductor Field Effect Transistor

MHz - Mega Hertz

MC-UWB

- Multicarrier Ultra Wideband

NF - Noise Figure

RF - Radio Frequency

RFIC

- Radio Frequency Integrated Circuit RFID

- Radio Frequency Identification

Rms - Root Mean Square

SNR - Signal to Noise Ratio

Spurs

- Spurious Signal S102

- Silicon Dioxide

S/H - Sample and Hold

UWB - Ultra Wideband

W - Width

WPAN - Wireless Personal Area Network

X111

CHAPTER 1

INTRODUCTION

1.1 Introduction

RF mixer is an essential part of wireless communication systems such as cellular phones, global-positioning systems, and wireless broadband Internet. These are things that need to be considered in designing RF mixer such as conversion gain, linearity, input impedance, port to port isolation and noise figure. RF mixer is placed between low-noise amplifier (LNA) and analog to digital converter (ADC) of the receiver and also known as down conversion mixer. The function of the mixer is to perform frequency translation by multiplying two signals together, and produce an output containing both original signals, and new signals that have the sum, and difference of the fi-equency of the signals. Mixers have been implemented in a wide variety of ways. The most popular are diode mixers, Gilbert mixers, FET mixers and sampling mixers.

1

The diode mixer is a very popular design and available in a wide variety of frequency bandwidth and distortion specs. The main disadvantages of diode mixer are large LO power is required. With this much LO power and even with good isolation, there may be significant LO in the IF output. At large RF signal power, the RF voltage modulates the diode conduction, thus lots of distortion will result in this situation. Diode mixer also limited by baluns. FET mixer is not as well known but it has a good performance. The conversion loss will be similar to the diode mixer and large LO drive voltage is needed. Gilbert mixer is very widely used active mixer because it has better isolation than the diode and FET mixers, and it also require less LO power than the passive mixers. Its main liability is large signal handling capability because IIP3 is much

lower than passive mixers. The sampling mixer is preferred because it generates fewer spurs. It also done in low frequency and has low power consumption.

In telecommunication systems, noise figure is a measure of degradation of the signal to noise ratio (SNR). The noise figure is the ratio of the output noise power of a device to the thermal noise in the input at standard noise temperature (290K). Basically, the noise figure is the difference in decibels (dB) between the noise output of the actual receiver to the noise output of an ideal receiver with the same overall gain and bandwidth. This make the noise figure a useful figure of merit for terrestrial systems where the antenna effective temperature is usually near the standard 290K. In this case, one receiver with a noise figure 2dB better than another will have an output signal to noise ratio that is about 2dB better than the other.

2

Due to demanding performance requirements for wireless systems, several technologies have been considered for replacing the current wireless systems which is ultra-wideband (UWB). Ultra-wideband is a radio technology that can be used at very low energy levels for short range high bandwidth communications by using a large portion of the radio spectrum. This method is using pulse coded information with sharp carrier pulses at a bunch of center frequencies in logical connections. UWB communications transmit in a way that does not interfere largely with other more traditional narrow band and continuous carrier wave uses in the same frequency band. In particular, UWB wireless system has potentially low power, high data rate and resilience to multipath fading effect.

In general, this thesis will focus on designing the circuit in reducing the noise figure of a sampling mixer for ultra-wideband at transceiver part. This analysis is done due to the characteristic of a sampling mixer itself and future demand of wireless systems.

1.2 Project Objectives

1. To investigate the technique and method used for sampling mixer in order to decrease noise figure (NF).

2. To design a circuit topology and measure all components of sampling mixer in order to meet the specifications for ultra wideband (UWB) applications.

3. To gain knowledge of PSpice software and the various type of analysis.

3

1.3 Thesis Outline

Chapter 1 describes the problems statement and the issues for the mixers and the demanding performance of ultra-wideband. Furthermore it is also listed the main objectives of the thesis.

Chapter 2, the literature review section describes the theory and fundamental concept of ultra-wideband, noise, mixer and low noise amplifier. It will explain in more detail about the design concept approach.

Chapter 3 discusses specification for the design analysis and the selection of the appropriate circuit technology. It also discusses the sampling mixer and LNA design.

The source determination and simulation results were stated with explanations. Thus, the design process was explained.

Chapter 4 discussed about the design simulation result and the analysis of the

circuit. The results are discussed and testified related to the objective of the project.

Chapter 5 summarizes all the analysis for this project. The conclusions are made in this chapter based on the result and analysis. The recommendation for future development and improvement are also included in this chapter.

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Pusat K. hidmat Maklumat Akademij UNIVERSITI MALAYSIA SARAWAK

CHAPTER 2

LITERATURE REVIEW

2.1 Ultra Wideband

Ultra wideband (UWB) communication systems can be broadly classified as any communication system whose instantaneous bandwidth is many times greater than the minimum required to deliver particular information. This excess bandwidth is the defining characteristic of bandwidth. The very first wireless transmission, via the Marconi Spark Gap Emitter was essentially a UWB signal created by the random conductance of a spark. The instantaneous bandwidth of spark gap transmission vastly exceeded their information rate. Users of these systems quickly discovered some of the most important wireless system design requirements which are providing a method to allow a specific user to recover a particular data stream and allowing all the users to efficiently share the common spectral resource.

5

In February 2002, Federal Communications Commission (FCC) legalizes Ultra Wideband (UWB) for commercial use with 7.5 GHz of unlicensed spectrum, allocated at 3.1 to 106 GHz frequency band. This opens a lot of commercial exploitation in short range high data rate wireless communication, Radio Frequency Identification (RFID), automotive sensor and through wall imaging. UWB allows up to a few centimeters ranging accuracy ranging and involve short discrete transmission pulses instead of continuously modulating a code into a carrier signal. This technology offers high data rates for radio communications, extremely high accuracy for location systems and good resolution for radars which using an inherently low cost architecture and only milli-watts of power. UWB has been the focus of much research and development recently. UWB offers solutions to applications such as see-through-the-wall, security applications, family communications and supervision of children, search and rescue, medical imagine, which makes UWB an ideal candidate for wireless home network [3].

UWB has several features that differentiate it from conventional narrowband systems;

i) Large instantaneous bandwidth enables fine time resolution for network time distribution, precision location capability or use as radar.

ii) Short duration pulses are able to provide robust performance in dense multipath environments by exploiting more resolvable paths.

iii) Low power spectral density allows coexistence with existing user and has a Low Probability of Intercept (LPI).

6

iv) Data rate may be traded for power spectral density and multipath performance.

UWB systems are unique because of their large instantaneous bandwidth and the potential for very simple implementations. Additionally, the wide bandwidth and potential for low-cost digital design enable a single system to operate in different modes as a communication device, radar or locator. Taken together, these properties give UWB systems a clear technical advantage over other more conventional approaches in high multipath environments at low to medium data rates.

Table 2.1: Summary of FCC restriction on UWB operation [3].

Application

^{Frequency Band for} Operation

User Restriction

Communications and 3.1 - 10.6 GHz (different None

measurement systems emission limits for indoor

(sensors) and outdoor systems)

Vehicular radar for collision 24 - 29 GHz None

avoidance, airbag activation

and suspension system

control

7

Ground penetrating radar to 3.1 - 10.6 GHz and below Law enforcement, fire and see or detect buried objects 960MHz rescue, research institution,

construction Wall imaging systems to 3.1

- 10.6 GHz and below Law enforcement, fire and

detect objects contained in 960 MHz rescue, construction

walls

Through wall imaging 1.99 - 10.6 GHz and below Law enforcement, fire and

systems to detect location or 960 MHz rescue

movement of objects located on the other side of

a wall

Medical system for imaging 3.1 - 10.6 GHz Medical personnel inside people and animals

Surveillance systems for 1.99 - 10.6 GHz Law enforcement, fire and

intrusion detection rescue, public utilities and

industry

8