ENERGY SCAVENGING FOR MOBILE AND WIRELESS DEVICE USING

HIGH-EFFICIENCY RECTIFIER CIRCUIT

LEE YOUHUI

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

i

ENERGY SCAVENGING FOR MOBILE AND WIRELESS DEVICES USING HIGH-EFFICIENCY RECTIFIER CIRCUIT

LEE YOUHUI

This Report Is Submitted In Partial Fulfillment Of Requirements For the Bachelor Degree in Electronic Engineering (Telecommunication Electronic)

Fakulti Kejuruteraan Elektronik dan Kejuruteraan Komputer

Universiti Teknikal Malaysia Melaka

JUNE 2016

ii

UNIVERSTI TEKNIKAL MALAYSIA MELAKA FAKULTI KEJURUTERAAN ELEKTRONIK DAN KEJURUTERAAN KOMPUTER

BORANG PENGESAHAN STATUS LAPORAN

PROJEK SARJANA MUDA II

Tajuk Projek : ENERGY SCAVENGING FOR MOBILE AND WIRELESS DEVICES USING HIGH-EFFICIENCY RECTIFIER CIRCUIT

Sesi Pengajian :

1

Saya ………………LEE YOUHUI……………………………………………………………………….. (HURUF BESAR) 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)

Tarikh: ……………………….. Tarikh: ………………………..

iii

DECLARATION

“I hereby declare that the work in this project is my own except for summaries and quotations which have been duly acknowledge.”

Signature : ....................................................... Author : LEE YOUHUI Date : .......................................................

iv

APPROVAL

“I acknowledge that I have read this report and in my opinion, this report is sufficient in term of scope and quality for the award of Bachelor of Electronic Engineering

(Electronic Telecommunication) with Honours.”

Signature : ....................................................... Supervisor’s Name : DR Wong Yan Chiew Date : .......................................................

v

DEDICATION

To dear mother and father and friends that give guidance to me

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ACKNOWLEDGEMENT

I was able to carry out this project with the help of my supervisor DR Wong

Yan Chiew and friend. I would like to take this opportunity to express my appreciation

to all those who helped me throughout my final year project. A special thanks to DR,

Wong Yan Chiew for her time and dedication for her guidance.

I also would like to extens my appreciation to my faily and friends. Thanks to

their support, financial support and encouragement. Besides, I also like to appreciate

my friends that assist me and give me guidance through the whole project.

Last but not least, I would further extend my appreciation to my faculty

FKEKK, which teach me and guided me with knowledge and ethic. Furthermore, I

would also like to appreciate the guidance and suggestion from panels of seminar

who give comment and advice which can improve my project.

vii

ABSTRACT

This project is to develop a high-efficiency RF to DC rectifier using CMOS

technology for an energy harvesting system. Energy harvesting or energy scavenging

is the process to harvest ambient energy from the atmosphere such as solar energy, RF

energy, vibration energy or thermal energy to a usable electrical signal. RF energy

harvesting is getting more demand because the density of the wireless communications

devices rapidly increases in metropolis area. This power extraction method able to

solve the growing demand for power supply to the low-power electronics. Therefore,

high efficiency of RF to DC rectifier is crucial. A high-efficiency CMOS based

rectifier has been developed enabling the integration of rectifier into any wireless

devices and mobile phone. Parametric simulations to the rectifier were done to

investigate factors that affect the power conversion efficiency of the rectifier. Circuit

parameters that been analysed including the sizing of the transistor, the threshold

voltage of the devices, load impedance, inter-stage capacitor and number of stages of

the rectifier. By using the optimized parameter set, we successfully achieve 13.3% of

conversion efficiency in a single stage rectifier. The conversion efficiency decreases

to 8.5% by increasing the number of rectifier’s stages to three.

viii

ABSTRAK

Projek ini adalah untuk membangunkan satu RF-kecekapan yang tinggi untuk

DC teknologi penerus menggunakan CMOS untuk sistem penuaian tenaga. penuaian

tenaga atau memerangkap tenaga adalah proses untuk menuai tenaga ambien dari

atmosfera sebagai tenaga solar, tenaga RF, tenaga getaran atau tenaga haba kepada

apa-apa isyarat elektrik yang boleh digunakan. RF penuaian tenaga semakin lebih

banyak permintaan kerana ketumpatan peranti komunikasi tanpa wayar cepat

meningkat di kawasan metropolis. Kaedah pengekstrakan kuasa dapat menyelesaikan

permintaan yang semakin meningkat untuk bekalan kuasa kepada elektronik kuasa

rendah. Oleh itu, kecekapan tinggi RF untuk DC penerus adalah penting. A penerus

CMOS kecekapan tinggi berasaskan telah dan dibangunkan membolehkan integrasi

penerus ke dalam mana-mana peranti tanpa wayar dan telefon bimbit. simulasi

parametrik untuk penerus itu dilakukan untuk menyiasat faktor yang mempengaruhi

kecekapan penukaran kuasa penerus. Parameter litar yang dianalisis termasuk saiz

transistor, voltan ambang peranti, beban impedans, antara peringkat kapasitor dan

bilangan peringkat penerus. Dengan menggunakan set parameter yang optimum, kami

berjaya mencapai 13.3% daripada kecekapan penukaran dalam penerus peringkat

tunggal. Kecekapan penukaran berkurangan kepada 8.5% dengan meningkatkan

bilangan peringkat penerus kepada tiga.

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TABLE OF CONTENT

NO TITLE PAGES

DECLARATION iii APPROVAL iv

DEDICATION v

ACKNOWLEDGEMENT vi

ABSTRACT vii ABSTRAK viii

LIST OF FIGURE xiii

LIST OF TABLE xv

LIST OF ABRREVIATIONS AND ACRONYMS xvi LIST OF APPENDIX xvii

I INTRODUCTION 1.1 Introduction 1

1.2 Problem Statement 3

1.3 Objective of Project 3

1.4 Scope of work 4

1.5 Organization of the Thesis 4

II LITERATURE REVIEW 2.1 Power Conversion Efficiency 5

2.2 RF Spectrum and Power Density 6

2.3 Architecture of RF to DC rectifier 7

2.3.1 Dickson Charger Pump Rectifier 7

2.3.2 Differential Drive CMOS rectifier 8

2.4 Different between single ended and differential ended rectifier 10

2.5 Factor that affecting the Power Conversion Efficiency 10

2.5.1 Sizing of the Transistor 11

2.5.2 ON-OFF characteristic of NMOS and PMOS 11

2.5.3 Threshold voltage of the NMOS and PMOS 12

x

2.6 Technique to enhance Power Conversion Efficiency (P.C.E) 12

2.6.1 Inter-voltage threshold cancellation technique 12

2.6.2 Self-Voltage threshold cancellation technique 13

2.6.3 Bulk Modulation technique 13

2.6.4 Floating gate technique 14

2.7 Comparing of literature review study 14

2.8 Summary 15

III METHODOLOGY 3.1 Flow Chart of Design methodology 17

3.2 Rectifier Identification 18

3.3 NMOS and PMOS device selection 18

3.4 Specification set 18

3.5 Simulation and circuit design 18

3.6 Layout design 19

3.7 Design rule check (DRC) 19

3.8 Layout vs. Schematic 20

3.9 Parasitic Extraction 20

3.10 Summary 20

IV SIMULATION AND DISCUSSION 4.1 Parametric simulation of a diode-connected PMOS and NMOS

between Thin oxide gate and thick oxide gate. 21

4.1.1 Parametric Simulation between PMOS Native Thin Oxide

and Thick Oxide 21

4.1.1 Parametric Simulation between NMOS Native Thin Oxide

and Thick Oxide 23

4.2 Schematic Design for RF to DC Rectifier 24

4.3 Parametric analyses on three stages of rectifier 26

4.3.1 Voltage gain when varying voltage amplitude 26

xi

4.3.2 Rise time of the Rectifier 28

4.3.3 Capacitor load of the Rectifier 29

4.3.4 Single Stage performance 31

4.4 Optimizing proposed in three stage for SVC with Dickson 32

4.4.1 Power Conversion Efficiency with different frequencies 32

4.4.2 Power Conversion Efficiency with different inter-stage

capacitor 32

4.4.3 Power Conversion Efficiency with different load impedance

33

4.5 Parametric analysis for single stage 34

4.5.1 Sizing of the NMOS 34

4.5.2 Sizing of the PMOS 35

4.5.3 Power conversion efficiency with different input voltage

levels 36

4.6 Prototype rectifier using Diode for Dickson Charger Pump 38

4.6.1 Measurement Result 40

4.7 Layout Design for SVC with Dickson Charger Pump 41

4.8 Summary 42

V ANTENNA DICUSSIONS 5.1 Important of Antenna in RF scavenging 43

5.2 Comparing Different Type of Antenna 44

5.3 Theory of Microstrip Rectangular Shape Antenna 46

5.4 Summary 48

VI CONCLUSION AND RECOMMENDATION 6.1 Conclusions 49

6.2 Recommendations 50

6.3 Sustainability and commercialization 50

xii

REFERENCE 51

APPENDIX A 53 APPENDIX B 54

APPENDIX C 58

xiii

LIST OF FIGURE

NO TITLE PAGES

1-1 Common energy harvesting system 2

2-1 RF spectrum and microwave 6

2-2 Maximum Power Transfer in different free space 7

2-3 conventional Dickson Charger Pump 8

2-4 Differential Drive CMOS rectifier 9

2-5 ON-OFF characteristic 11

2-6 IVC technique implement in DPC 12

2-7 SVC technique 13

3-1 Flow diagram of this Project 17

3-2 Floor management 19

3-3 DRC check 20

4-1 PMOS in Diode connected 22

4-2 I drain vs. Voltage sweep 22

4-3 NMOS diode-connected 23

4-4 I drain vs. Voltage sweep 24

4-5 Differential Drive Rectifier 24

4-6 Dickson's Charger pump 25

4-7 SVC with Dickson 26

4-8 Vout Vs Vpeak 27

4-9 voltage conversion efficiency vs. Vrms with load resistor 27

4-10 Rise time 29

4-11 Rise time for DDR 30

4-12 Rise time for proposed design 30

xiv

4-13 Efficiency vs. Frequency 32

4-14 Efficiency vs. Different Stage Capacitor 33

4-15 Efficiency vs. Rload 34

4-16 Efficiency vs. the width of the NMOS 35

4-17 Efficiency VS the width of PMOS 36

4-18 input current with increasing width of PMOS 36

4-19 Efficiency with different input voltage 37

4-20 Input current with increases of input voltage 37

4-21 Schematic of Dickson charger pump in ADS 2011.1 38

4-22 Transient analysis of rectified output voltages for different input

voltages 39

4-23 Fabricated DCP using Diode 39

4-24 Measuring Result using Oscilloscope 40

4-25 Measured output voltage of DCP in Vrms in the frequencies setting of

1MHz, 4MHz, and 10MHz. 40

4-26 Measured Output power for different source frequencies for R =1KΩ

and Cload = 470µF

41

4-27 Layout Design of SVC with Dickson 42

5-1 Microstrip Patch antenna 44

5-2 Rectangular Patch Antenna 47

xv

LIST OF TABLE

NO TITLE PAGES

2-1 Different between single ended and differential ended 10

2-2 Comparing different type of Benchmarking 14

4-1 Adavntage and Disadvantage of the Native thin oxide and Thick oxide 22

4-2 Parameter for simulation 25

4-3 Optimisation of the size of the PMOS in SVC 31

4-4 Optimisation of the size of the NMOS in SVC 31

4-5 Parameter that changes that affected 35

5-1 Parameters study of Antenna 44

xvi

LIST OF ABRREVIATIONS AND ACRONYMS

RF Radio Frequency

NMOS N-type metal-oxide-semiconductor logic

PMOS P-type metal-oxide-semiconductor logic

P.C.E Power Conversion Efficiency

ADS2011.1 Advanced System Design 2011.1

DC Direct Current

CMOS Complementary metal–oxide–semiconductor

SVC Self-Threshold Voltage Cancellation

IVC Inter threshold Voltage Cancellation

DCP Dickson Charger Pump

DRC Design Rule Check

LVS Layout vs. Schematic

DDR Differential Drive Rectifier

PIFA Planar Inverted F Antenna

xvii

LIST OF APPENDIX

NO TITLE PAGE

A DATA SHEET OF IN5819 53

B A PARAMETRIC STUDY ON SVC DICKSON

RECTIFIER FOR RF MOBILE SCAVENGING

SYSTEM

54

C DESIGN AND DEVELOPMENT OF REDUCED

THRESHOLD VOLTAGE RECTIFIER FOR RF

MOBILE SCAVENGING SYSTEM

58

1

CHAPTER 1

INTRODUCTION

1.

Chapter 1 consist of the background of the project for this dissertation. A few

major energy harvesting problem was presented in the introduction. Secondly, this

section consists of another four major part which consists of the problem statement,

the objective of this dissertation, scope of work for this project and Outline of this

thesis.

1.1 Introduction

Energy harvesting or energy scavenging is the process to harvest ambient

energy from the atmosphere such as solar energy, RF energy, vibration energy or

thermal energy to a usable electrical signal. RF energy harvesting is getting more

demand because the density of the wireless communications devices rapidly increases

in a metropolis area [1]. This power extraction method can solve the growing demand

for power supply to the low-power electronic consumption, such as wearable devices,

wireless devices, mobile phone and sensors. All this application required a battery as

an energy source [2]. Therefore, high efficiency of RF to DC rectifier is crucial.

Since the advancement of nanotechnology, industries able to implement a

smaller size electronic circuit with low power application. This development can

integrate into a wireless sensor network, biomedical devices, wearable device, and

mobile phone. But all these devices required an energy source such as supply battery

power to it [2-4]. Furthermore, there is no development in battery technology. Which

is a tradeoff for nanotechnology. Besides that, the battery is bulky, limited supply and

chemical hazard when implemented in biomedical devices. Therefore, RF harvesting

is the solution for this problem. To improve the power conversion efficiency the power

consumption, voltage threshold needs to be reduced.

2

Different topologies of RF to DC rectifier had been discussed in [1, 5-11]. The

most popular rectifier discussed are Dickson’s charger pump, differential drive

rectifier, Villard converter and another type of AC to DC Converter which able to

implement in CMOS technology. To improve the efficiency of the rectifier, different

types of internal voltage cancellation technique had been introduced. As an example,

internal voltage cancellation (IVC), self-voltage cancellation and floating gate

techniques. These techniques can improve the power conversion efficiency, which

enables the harvester to accumulate the surrounding ambient energy to the energy

storage for a lifetime.

Figure 1-1 Common energy harvesting system

Figure 1-1 illustrate the block diagram of the energy harvesting system. It

includes four main components that contribute to the overall system before supplying

energy to the devices.

Transducer

The transducer is used to harvest the ambient energy then converts usable

energy. As an example, RF antenna to convert the RF energy to the electrical

energy. It can be AC or DC circuit.

RF to DC rectifier

RF to DC rectifier or converter is used to convert the AC electrical energy

to useable DC energy. It can be voltage multiplier that rectifies the AC electrical

energy to DC electrical energy. The DC electrical energy will be amplified.

TransducerRF to DC rectifier

Power management

Energy Storage

Devices

3

Power management

The power management circuit depends on its applications; it can use to

regulate a stable DC voltage by using buck or boost converter and limited by

voltage limiter. This system can control the conveying of the electrical path

between the devices and the harvester.

Energy storage

The charge storage is to store the harvested energy, either in a capacitor or

rechargeable battery or another type of storage element.

1.2 Problem Statement

Energy harvesting or energy scavenging is the process to harvest ambient

energy from the atmosphere such as solar energy, RF energy, vibration energy or

thermal energy to a usable electrical signal. RF energy harvesting is getting more

demand because the density of the wireless communications devices rapidly increases

in a metropolis area [1]. This power extraction method able to solve the growing

demand for power supply to the low-power electronics such as wearable devices,

wireless devices, mobile phone and sensors. All this application required a battery as

an energy source [2]. Therefore, RF to DC rectifier will be the crucial point to improve

the efficiency.

1.3 Objective of Project

Conventional RF to DC rectifier uses Schottky diodes to develop, which is

bulky and not suitable for smaller devices. Therefore, RF to DC rectifier will be

implemented in CMOS process technology. In this project emphasize on the power

conversion efficiency and parameter that affect it.

The main objective of the project is:

1. To design and develop a high-efficiency rectifier for an RF harvesting system that able to applied to the wireless device and mobile devices.

2. To investigate parameter that affects the power conversion efficiency in the rectifier.

3. To optimize the RF to DC rectifier

4

1.4 Scope of work

This project focuses on the higher power conversion efficiency in 130nm

silterra process technology. The main scope of the project is:

To enhance the power conversion efficiency of the rectifier To design and simulate an RF to DC rectifier using two types of voltage

cancellation technique To study two types of rectifier topologies and benchmark with the existing

study in the journal. To studies the parameter such as the width of the transistor, various input

voltages, and different output impedance.

1.5 Organization of the Thesis

This thesis consists of five chapters and the overview of all the chapter as

follows:

Chapter 1: This chapter provides a brief introduction to the background,

problem statement, and scope of work involved in accomplishing this project.

Chapter 2: a Literature review on the fundamental of Power Conversion

Efficiency (P.C.E), an overview of the two types of RF to DC converter which is a

Dickson charger pump and a differential drive CMOS rectifier. And technique to

improve the P.C.E and the parameter that affect it.

Chapter 3: This chapter gives an overview of the fundamental to design the RF

to DC rectifier, simulation and the overall procedure for Analog IC design.

Chapter 4: This chapter describes the simulation and simulation result of this

project, including a description and discussion.

Chapter 5: conclusion in chapter 5 and followed by the recommendations for

future work.

Next, the thesis has contributed some technical papers which to be published

as shown in Appendix part.

5

CHAPTER 2

LITERATURE REVIEW

2.

This chapter consists of 7 major parts the first parts explains on the Power

Conversion Efficiency of the rectifier, then the fundamental of the RF Spectrum and

power density in free space. In the third part the RF to DC architectures are a review,

then follow up by the difference between single ended rectifier and differential ended

rectifier. In this section, a review in the factor that affects the Power Conversion

Efficiency, which included: Threshold voltage, sizing and On-off characteristic of the

rectifier. A further review of different threshold voltage cancellation was done. Last

and not least a further comparing with different rectifier are present this chapter.

2.1 Power Conversion Efficiency

Power Conversion Efficiency or P.C.E is the main criteria will be focused on

this project. As the higher the converted harvested energy, the higher the P.C.E in the

RF to DC rectifier. From [1, 2] the power conversion efficiency is defined as equation

[1].

𝑃. 𝐶. 𝐸 = 𝑃𝑑𝑐

𝑃𝑟𝑓

Where Pdc is the power from the load terminal, then Prf is the input power from the

input terminal at the Voltage peak of the sinusoidal.

6

2.2 RF Spectrum and Power Density

RF Spectrum consists of different operating band frequency; each band

consists of different application and function for wireless communication system.

Figure 2-1 shows the spectrum of the RF spectrum that able to harvest from the

surrounding.

Figure 2-1 RF spectrum and microwave

In this project, the targeted operating band will be RF spectrum, which consists

of TV, FM or AM radio, Mobile phone, UMTS and another type of wireless devices.

This radio wave consists of magnetic and electric radiation component that enable

wireless communication to transmit information. Information is pass through different

modulation technique and amplitude inside the signal. Wireless communication

devices use the antenna as the transmitting medium to convert electrical signals to an

RF signal. This requires certain power to be transmitted to the thin air. Therefore, it

can be harvested using an antenna to convert the RF signal to usable electrical signal.

The theoretical maximum power available power for conversion is 7.0uW and 1.0uW

for the frequency of 900MHz and 2.4MHz respectively within the free space of 40m

[12].

7

Figure 2-2 Maximum Power Transfer in different free space

2.3 Architecture of RF to DC rectifier

Conventional rectifier used four diodes to create full bridge rectifier, but this

rectifier had a high voltage drop which results in the power conversion efficiency to

drop. As some of the voltage is used to power up the diode. To achieve high power

conversion efficiency, Schottky diode is used as it has lower threshold voltage than a

conventional diode. But Schottky diode is bulky and not able to implement in CMOS

technology, as the Schottky diode required more cost to fabricate in CMOS technology

process.

2.3.1 Dickson Charger Pump Rectifier

The Dickson charger pump is the most common RF to DC converter in the RF

harvesting system, [1] and [13] which used a different type of cancellation method.

Figure 1 shows the Dickson charger pump which will be used for the prototype of RF

to DC rectifier.