Design Project 2 Final Report

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ULTRA WIDEBAND IMPULSE RADIO TRANSMITTER CHARACTERIZATION

ECSE 457

Authors:

George Lee (260397078)

Lulan Shen (260449509)

Supervisor:

Professor Frederic Nabki

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Abstract

This project was on designing and implementing a low power functional ultra wideband

transmitter using a 0.13µm CMOS chip on a PCB connected with a FPGA board. The CMOS

chip was wire bonded and packaged with a ceramic lid. The package was placed in a 28 pins, 7 x

7, 0.8mm pitch elastomer Ironwood socket that was directly mounted on to the PCB. Using

PADS 9.5, we designed and fabricated the PCB layout for the CMOS chip. A Spartan 6 FPGA

board was connected to the PCB using a VHDCI to control the input signals to the CMOS. After

assembling all the components, we tested the designed functions of the CMOS such as power

cycling, frequency, width and phase modulation. The power spectrum density and transmission

line parameters such as the S11, S12 and S22 were also measured.

The motivation for this project is to have the chance to potential enhance society by

successfully testing an IC chip, which could potential be manufactured for consumers. Our ultra

wideband IC chip is a strong candidate for short distance wireless low power and data rate

transmissions such as a pacemaker. The possibility of this device impacting various industries is

quite potent. [1]

Acknowledgment Section

We are using this opportunity to express my gratitude to Professor Frederic Nabki for

providing us the opportunity for such an intricate and high level microelectronics design project.

We want to thank Professor Frederic Nabki for providing the necessary equipment at UQAM for

this project to be possible.

We would also like to express a warm thank you to Rabia Rassil, Professor Nabki’s

student, for providing invaluable services such as helping us understand the CMOS chip,

teaching us the computer software necessary, and supervising the project. We are sincerely

grateful for the help Rabia has provided us.

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Table of Contents

Table of Tables…………………………………………….................…………..............…...…4

Table of Figures………………………………………….................……...................................4

Abbreviations…………………………………………………………........................................7

Introduction/Motivation/Objective…………………………………...........................................8

Background Chapter……………….……………………..………..............................................9

Requirements and Problems……………………………………………………………….…...13

Design and Implementation Chapter…………………………...............................................…18

PCB Design………………………………………………….................................................…18

Experiment Results……………………………………………………………….………….....26

Impact on Society and the Environment…………………………………...................……...…35

Report on Teamwork……………………………………………………................…...…...….37

Conclusion………………………………………………….......................................……..…..38

References……………………………………………………........................................……...38

Appendices………………………………………………………..............................................39

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List of Tables

Table 1 Abbreviation .................................................................................................................................... 7

Table 2 Datasheet of IC .............................................................................................................................. 39

Tables of Figures

Figure 1 Ultra Wideband Frequency Spectrum ............................................................................................ 9

Figure 2 Pulse generation and transmission for OOK modulation .............................................................. 10

Figure 3 OOk Pulse Transmission ................................................................................................................ 10

Figure 4 PPM Pulse Transmission .............................................................................................................. 10

Figure 5 BPSK Negative One Pulse .............................................................................................................. 11

Figure 6 Figure 6 BPSK Negative One Pulse.............................................................................................. 11

Figure 7 Transmitter Diagram ..................................................................................................................... 11

Figure 8 Receiver Diagram ......................................................................................................................... 12

Figure 9 The Ten Step Flowchart ................................................................................................................ 13

Figure 10 IC Chip Layout ........................................................................................................................... 14

Figure 11 Transmitter bonding diagram ...................................................................................................... 18

Figure 12 Receiver bonding diagram .......................................................................................................... 18

Figure 13 Our Socket .................................................................................................................................. 23

Figure 14 Our IC chip ................................................................................................................................. 23

Figure 15: Socket Mechnical Schematic graph ........................................................................................... 24

Figure 16: Transmitter PCB schematic design ........................................................................................... 18

Figure 17: Transmitter chip design………………………………………………......................................20

Figure 18: Transmitter decal (footprint) ..................................................................................................... 19

Figure 19: VDD_S2D connection with transmitter (TX) chip…………………………………………....20

Figure 20: Power connector, switch and LED ............................................................................................ 19

Figure 21: 0 to 1.2V power supplies…………………………………………………………………..…..21

Figure 22: 0 to 1.4V power supplier with transmitter (TX) ........................................................................ 20

Figure 23: VDD_BIAS connection ............................................................................................................. 20

Figure 24: Buffer Stage ............................................................................................................................... 21

Figure 25: Transcmitter PCB Final Layout ................................................................................................. 22

Figure 26: Transcmitter PCB Board without Components ......................................................................... 22

Figure 27: Transcmitter PCB Board with Components .............................................................................. 23

Figure 28: Output Pulse Frequency Versus Frequency Control Signal Bits ............................................... 25

Figure 29: Output Pulse Width Versus Width Control Signal Bits ............................................................ 25

Figure 30: Pulse frequency = 6.2GHz with frequency control signal bits 011 ........................................... 26



Figure 33: Phase modulation comparison at 3.2GHz.................................................................................. 27

Figure 34: Phase modulation comparison with 1.1ns width ...................................................................... 28

Figure 35: Pulse width = 0.38ns with width control bits 0000………………………………...……….....28

Figure 36: Pulse width = 0.68ns with width control bits 0011 ................................................................... 28

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Figure 37: Pulse width = 0.92ns with width control bits 1111……………………………………………29

Figure 38: Pulse width = 1.4ns with width control bits 1011 ..................................................................... 29

Figure 39: Frequency and Width Modulation for Output Signals .............................................................. 29

Figure 40: PSD Spectrum of Sample Sequence With All Frequencies....................................................... 30

Figure 41: PSD Spectrum of Sample Sequence from 4 to 5.5GHz ............................................................ 31

Figure 42: PSD Spectrum of Sample Sequence At Without 4 to 5 GHz ................................................... 31

Figure 43: Plot of Power Consumption versus Data Rate........................................................................... 32

Figure 44: Plot of S11 of Transmitter ......................................................................................................... 33

Figure 45: Plot of S11 of Transmission Line .............................................................................................. 33

Figure 46: Plot of S11 of Improved Transmission Line .............................................................................. 34

Figure 47: Plot of S12 of Improved Transmission Line .............................................................................. 34

Figure 48: Transmission line comparison ................................................................................................... 35

Figure 49: Pulse frequency with frequency control signal bits 010 ............................................................ 40


Figure 51:Pulse frequency with frequency control signal bits 100 ............................................................. 41










Figure 61: Pulse width with width control bits 0000 .................................................................................. 46




















6













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Abbreviation

Table 1 Abbreviation

Abbreviation Definition

UWB Ultra Wideband

IR Impulse Radio

PCB Printed Circuit Board

FPGA Field Programmable Gate Array

CMOS Complementary Metal Oxide Semiconductor

TX Transmitter

RX Receiver

IC Integrated Circuit

OOK On/Off Switch Keying

BPSK Binary Phase Shift Keying

LNA Low Noise Amplifier

VCRO Voltage Controlled Ring Oscillator

VHDL VHSIC Hardware Description Language

VHSIC Very High Speed Integrated Circuit

PPM Pulse Position Modulation

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Introduction

For our design project, we are designing and implementing a low power functional ultra

wideband transmitter using a 0. 13µm CMOS chip. The CMOS chip was designed by one of

Professor Nabki’s graduate students. The package will be placed in a 28 pins, 7 x 7, 0.8mm pitch

elastomer Ironwood socket that is directly mounted on the PCB. Using PADS 9.5, we designed

and fabricated the PCB layout for the CMOS chip. After the fabrication of the PCB, we soldered

all the components onto our PCB such as resisters, capacitors, potentiometers, IC regulators, test

points, VHDCI and etc. A Spartan 6 FPGA was connected to the PCB using a VHDCI to control

the input signals to the CMOS. After assembling the components, we tested the designed

functions of the CMOS such as power cycling, frequency, width and phase modulation. The

power spectrum density and transmission line parameters such as the S11, S12, and S22 were

also measured.

In design project 1, we researched about the UWB, understood the chip, learned PAD

Logic/Layout and started the PCB layout. In design project 2, we were able to get the chip wired

bonded, PCB fabricated, components soldered, programmed FPGA using VHDL and CMOS

functionality tested. A full outline of our project milestone steps will be included in

Requirements and Problems Chapter.

Motivation

The motivation for this project is to provide an IC chip that will have the capability of

impacting society, which if works could more than likely be manufactured and fabricated for

consumers. This IC chip is great for various wireless applications for short distances that requires

low power and data rate transmissions. There are countless applications that could benefit from

this chip. Besides contributing to society on a large scale, we are also able to learn a great deal

from this project. As students, often we aren’t able to get enough hands on experience through

labs. This project will gives us hands on experience with developing and testing an IC chip at a

very high level. This project will be incredibly useful in getting a taste of the IC fabrication and

testing industry.

The motivation for this project will be described in more detail in the “Impact to Society”

section, giving the reader much more insight into the actual usefulness of our IC chip and the

various parts of society it touches on. By completing our project, we will be able to contribute to

society on a large scale. [1]

Objective

The goals of this project are quite simple. The main goals of this project is to design and

implement a low power UWB transmitter. After assembling the UWB transmitter, we will be

testing the functionality of the CMOS chip such as power cycling, frequency, width and phase

modulation. The PSD of the chip and transmission line such as the S parameters will also be

tested.

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Background Chapter

In the background chapter, we will be describing the theory of we have learned over the

course of design project one such as ultra wideband, Impulse Radios, OOK, PPM, BPSK,

transmitter and receiver diagrams. In the following sections, we will describe each concept in

detail. [1]

Ultra Wideband

Figure 1 Ultra Wideband Frequency Spectrum

Ultra wideband has a very wideband in the frequency spectrum, ranging from

approximately 3 to 10 GHz, shown in the figure above. UWB communication uses very short

pulses with relatively low energy and has relatively good penetration capabilities due to the large

bandwidth. UWB technology doesn’t require a carrier such as one required in radio techniques

using a mixer. Because the UWB technology doesn’t require a carrier, this allows much simpler

and lower cost transmitters and receivers. [2]

Impulse Radio

One of the main UWB technologies is the Impulse Radio. The impulse radio sends very

short pulses usually only a few nanoseconds. There are many advantages to having vary narrow

pulses, such as having low transmission power due to not having to send large pulses. The time

resolution of the IR is very defined and high resolution. The impulse radio also doesn’t use a

carrier. Aside from Impulse Radios, there is also multiband OFDM technology, which is

relatively more complex and power consuming. Our specific IC chip uses impulse radio

technology. [1]

Types of Modulation

So our IC chip design is to use 3 types of modulations, On/Off Switching Key (OOK),

Pulse Position Modulation (PPM), and Binary Phase Shift Keying (BPSK). For our IC chip,

http://www.theiet.org/resources/journals/eletters/4811/non-stop-rejection.cfm

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transmitter is able to transmit all three types of modulations. However, our receiver is only

capable of decoding OOK and PPM transmission. In next sections, we will describe how our IC

chip uses the three types of modulations listed. [1]

On/Off Switching Key

Figure 2 Pulse generation and transmission for OOK modulation

OOK stands for on off switch keying. The way OOK works is there’s a pulse generator

that generates a Gaussian pulse, which is then modulated with the green sinewave to create a

pulse shown in the picture to the right. The number of pulses generated for a certain period

correlates to the actual value. So for example 3 pulses transmitted, would represent a 3. 7 pulses

would represent a 7 and so on. There is sleep time between the transmissions, so we can save

power by shutting off during sleep period. [1]

Pulse Position Modulation

Figure 3 OOk Pulse Transmission

Figure 4 PPM Pulse Transmission

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As you can see from 0-10 there’s 3 pulses so it represents a 3, that’s OOK. PPM stands

for pulse position modulation which literally uses the position of the pulse to transmit data. So

for our receiver, we essentially have 2 windows of capturing transmitted data. The first window

is from 0 to 5 and the second is from 5 to 10. If the pulse is transmitted during the first window,

it represents a one. While the pulses captured in the 2nd window represents a 0. There are many

ways to encode PPM. Our device uses this simple 2 window encoding method. [1]

Binary Phase Shift Keying

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

-0.1

-0.05

0

0.05

0.1

0.15

Time (ns)

Am

plit

ud

e (

V)

Figure 5 BPSK Negative One Pulse

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

-0.1

-0.05

0

0.05

0.1

0.15

Time (ns) Figure 6 BPSK Negative One Pulse

BPSK stands for binary phase shifting keying. It uses the phase of the carrier changes

accordingly to a digital signal. The first picture represents a negative one and the second a

positive one. As you can see negative one has a 180 phase difference from positive one,

reversing the pulse. Essentially, BPSK is able to implement trinary logic, as well as binary.

Negative one could also be used as a hard zero, to make sure that the value is actually 0 and not

some sort of noise. [1]

Our IC transmitter is able to transmit using BPSK however, our receiver doesn’t have the

function of detecting negative one from positive one at the receiver end. This could be part of the

design step at the very end of the design project. [1]

Transmitter

Figure 7 Transmitter Diagram

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The first step for the transmitter is to combine the data and clock together using AND

logic gate, which then feeds the data to the pulse generator. By using the pulse generator, we are

able to vary the pulse width by using the controls “a<0:2>.” The VCRO, voltage controlled ring

oscillator, will then generate a modulated pulse, which will then be amplified by the S2D, single

to double. The purpose of the amplifier having two different outputs, is for the transmitter to

have the ability to send two types of pulses for BPSK, positive and negative one. The driver then

further amplifies the pulse before the antenna transmits it. Like all analog signals, there will be

pad and package parasitics. [1]

Receiver

Figure 8 Receiver Diagram

On the receiver end, the signal is received by the low noise amplifier (LNA), which will

amplify the weak signal, while not amplifying the noise. The squarer will modify the signal,

which will feed the pulses to another amplifier who will further amplify the signal. The

integrator will essentially create a stair shaped figure, which the comparator will find the value of

what the data should be from 0 to 7. The encoder will then encode 0-7 to a 3 bit binary logic. [1]

Package

The actually IC chip is very delicate, so we don’t solder the IC chip directly the printed

circuit board, which is describe in the next section. Instead we wire bond the IC chip to the

package, which then provides pins for access to the IC chip. [1]

Printed Circuit Boards

Printed Circuit Boards (PCB) are used to connect electronic components using a specially

design layout. The process of fabricating printed circuit boards is quite complex and requires

multiple layering, plating and coatings. We will be using it to connect our IC chip to its power

supply and FPGA. [1]

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Socket

A socket is essentially used in between the package and the printed circuit board. The

purpose of the socket is so that we do not need to solder the package onto the PCB, making it

relatively easier to swap out packages. [1]

Requirements and Problems

Outline

For our design and implementation, after a long meeting with Professor Nabki, we have

set out an outline of our 10 step milestone goals for both Design project 1 and 2. The 10

milestones have been changed slightly since Design Project 1 report. We were able to complete

milestones 1 to 3 in Design Project 1, while finishing milestones 4-10 in Design Project 2.

The following steps are our 10 milestone goals: Understand the Chip, Data Sheets, PCB

Features and Layout, Wire Bonding, PCB Fabrication, Soldering, FPGA, Testing Chip,

Improvements, and Future works. Each step will be elaborated in more detail in sections below.

Figure 9 The Ten Step Flowchart

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First Milestone: Understand Chip

For our first milestone goal, “Understand the Chip,” we used the first month of Design

Project 1 to do intensive research on the theory of ultra wideband and preparing a PowerPoint

presentation of over 20 journals combined. For each journal we had a 3 step process: Summary

of the journal, Key Terms with brief definitions and the overall theory implemented. We found

that using UWB-IR have many advantages when used in small low power wireless transmitters.

[1]

The main advantages are that they require very low power, relatively simple and very

small. Since there are countless applications that need low power wireless transmission with low

data rates, UWB-IR is a strong candidate for this purpose. The specific theory and research done

is shown in the Background Chapter. The next step will involve the IC datasheet, shown in the

Appendix. [1]

Figure 10 IC Chip Layout

Second Milestone: Data Sheet

The second milestone goal is to understand the “Data Sheets.” After getting relatively

familiar with UWB-IR, we then dived into understanding version 1 and 2 of the chip designed by

Professor Nabki’s graduate student. The first step was to figure the circuit out, while looking at

the datasheets to know the purpose of each component, specifically on the PCB. Since in third

milestone includes doing the PCB Layout, this task would be impossible to do without absolutely

understanding the data sheets and knowing the purpose of each component as well as the

connections between components. [1]

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At first, looking at the data sheets for the package that showed the name of each pin, the

task of implementing version 2 of the chip seemed insurmountable. However, taking a closer

look at it, we realized most of the pins had to do with power supply, making things a little bit

easier. The datasheets even indicated, which pins were TX and RX. In version one, the package

had 64 pins that included both TX and RX. In our version 2, we have 2 separate 28-pin packages,

one for TX and one for RX. [1]

Third Milestone: PCB Layout

For the third milestone, our goal is to design and set the “PCB features.” The first step

before beginning the PCB Features and Layout, we have to get familiar with the software PADS

9.5. We spent over one whole week to finish 8 weeks’ worth of tutorials with the help of one of

Professor Nabki’s student in UQAM. In these tutorials, we learned how to create a schematic

using PADS Logic, which then generates a net list for the PADS Layout. [1]

After importing the net list, we will be able to draw the PCB layout and the trace,

connecting various components. Essentially, drawing the PCB layout is quite challenging and

requires a lot of time and accuracy. This PCB Layout is then sent to a private company to

produce our specifically design PCB layout. The process of fabricating the PCB can take up to 3

to 4 weeks’ time. [1]

One of the PCB features we wanted to implement was to include a socket. The socket

will essentially goes between the package and the PCB. The purpose of the socket is so we don’t

have to directly solder the package onto the PCB, making it easier to remove and replace the

package if anything is goes wrong with the package. So instead of soldering the package onto the

PCB, attaching the socket to the PCB using through holes with screws and bolts.

Our socket specifications required 28 pins, 7 x 7, 0.8mm pitch. We were able to contact 5

companies that have sockets with our specification, but most companies didn’t have sockets with

our specifications. We were able to purchase an Ironwood socket for $270 that used elastomer as

a connection pad. The PCB features will be described in detail in the “Design and

Implementation” section.

Fourth Milestone: Wire Bonding

The four milestone is wire bonding, which is also known as packaging a chip. The

purpose of the packaging the chip is essentially to protect the chip from being damaged and for

soldering purposes. The IC chip could be soldered directly the PCB, however, it will be

impossible to successfully de-solder the IC chip without destroying the chip. The IC chip is

connected to the package with extremely thin wires.

We designed the wire bonding of the package and IC chip using PADS 9.5. The IC chip

had 64 pins and was originally designed to include both the transmitter and receiver together. In

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our project, we will only be using the transmitter part of the IC chip, 28 pins. After virtually

connecting the wire bonds, the IC chip and package was given to Polytechnique Montreal to wire

bond for a price of $300 and took over 3 weeks to package. A more detailed description of the

wire bonding process is described in the “Design and Implementation” section.

Fifth Milestone: PCB Fabrication

For the fifth milestone, we sent our PCB layout to a private company to be fabricated,

costing $200 for 2 boards. While the waiting for our PCB and packaged chips, we bought all the

components needed for the PCB on Digi Keys costing $350. These components included IC

regulators, potentiometers, capacitors, resistors, inductors, VHDL connectors, SMA connectors,

test points, switch, LED lights, and buffer.

Sixth Milestone: Soldering

In the milestone outline, our sixth step was the “PCB Soldering” after receiving our

newly packaged chip and PCB. Although we used private companies to fabricate the PCB and

wire bond our IC chip, we will be doing all the soldering by ourselves.

There is two types of soldering: surface mounted soldering and through hole. We will

first solder all the surface mount components before moving onto through hole. We will put

some tin between the surface mount soldering components and our PCB board, then put the

board into a special oven in UQAM for around 30 minutes. [1] For our through hole components,

we will be using a soldering iron and soldering those by hand because most of these components

will melt if we put them into the oven. The package has a ceramic lid, which is soldered using

surface mount technique using the oven.

Seventh Milestone: FPGA

The seventh milestone step was to customize the “FPGA” for our specifications. The

specific board we will be using is the Spartan 6 development board. After finishing the PCB and

receiving the product from the fabricators, we will be connecting the Spartan 6 board to our

PCB. The use of the FPGA is to give our IC chip a signal to transmit and to provide the clock.

We will also be using it to test whether our receiver to see if the output is what we’re expecting.

The language we will be using is VHDL to program the Spartan 6. [1]

The FPGA will be used to control the input signals of the IC chip, and will be connected

to the PCB using a VHDL connector. Our VHDL code will allow us to control the frequency,

width and phase of the output signal, which is essentially for the types of modulation we desire:

On/Off Switching Key, Pulse Position Modulation, and Binary Phase Shift Keying.

Eighth Milestone: Testing Chip

The eighth milestone goal was to test the chip. Essentially, this step we planned the kind of

preliminary tests on the UWB chip. The first step after receiving the PCB and soldering was to

first use the multi-meter probe in diode test mode to check for any misconnections or unwanted

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shorts on the circuit board. [1] We had some problems with misconnections after we soldered all

our components onto the PCB. Some of the solder paste of the surface mounts accidently shorted

some connections.

After checking for misconnections, we turned off the clock and data signal to check the

bias and power supply individually. We first checked to see if the LED is on for the bias and

probe the voltage. After checking the bias, we turned off the BIAS and turn on the power supply.

Using similar techniques in checking the bias, we will make sure the power supply is at the

correct voltage. We had problems with broken potentiometers and contact between the PCB and

components for surface mount. To enhance the connection, we soldered by hand the connections

that were having problems.

After assuring that the power supply works as expected, we will then test the control

signals from the FPGA. [1] This step is the most important step and tested the desired functions

of the 3 types of modulation. The Power Spectral Density and Fast Fourier Transform of the

output signal was also tested.

Ninth Milestone: Improvements

The ninth milestone of the project was to improve the output signal. We took the S

parameters of our transmission line and realized that our actual values was shifted by 3GHz

compared to the actual values. To improve the transmission line, we ordered a better PCB from

Roger’s Company, which substantially increased the output of the signal. The improvements of

the S parameters are described in detail in the “Design and Implement” section.

Tenth Milestone: Future Works

For the tenth step of the future work is to finish implementing the receiver. So far we

have been able to finish the PCB layout of the receiver. We are having trouble making the

receiver functional at the moment. Some other things that could be done is to re-design a newer

IC chip version of the transmitter. The design of the IC chip will be very challenging due to the

complexity of the circuit.

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Design and Implementation Chapter

PCB design

Check bonding by using the new datasheet

Figure 11 Transmitter bonding diagram

Figure 12 Receiver bonding diagram

Both receiver and transmitter bonding are correct. Most of the pins are used for power

supply and biasing. Pin #1 starts from the bottom left corner and sequence of pins goes counter-

clockwise. Our transmitter and receiver chip will follow the same sequence in the PCB

schematic design. [1]

Transmitter PCB schematic design

Figure 13: Transmitter PCB schematic design

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In version 1, they made the transmitter and receiver on the opposite sides in the same

chip with 64 pins. There are more than 28 pins for transmitter and 28 pins for receiver. In our

version, we start to separate transmitter and receiver, producing chips to make our design

simpler. Each chip contains 28 pins. The transmitter chip and its decal are shown in Figure 14

and Figure 15. Transmitter design contains different power supplies, biasing stage, buffer stage,

transmitter chip, power switch, LED, and the holes on the PCB board, shown on Figure 13. [1]

Figure 14: Transmitter chip design Figure 15: Transmitter decal (footprint)

For the decal, the width of the pins after calculation by the computer is 0.8mm, which is

larger than it is specified in the datasheet (0.305mm). It won’t cause trouble and it will be easier

for us to solder our chip. [1]

Figure 16: VDD_S2D connection with transmitter (TX) chip Figure 17: Power connector, switch and LED

Connect and disconnect the power supply will cause unwanted current change. So the

improvement is to add a switch to control it. We decide to keep this improvement so far. The

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LED is used to detect whether there is a current flow inside. If the LED is not turn on, it might

imply the open circuit somewhere. Then we will try to figure out where is break. [1]

Figure 18: 0 to 1.2V power supplies Figure 19: 0 to 1.4V power supplier with transmitter (TX)

VDD_BIAS, VDD_TX and

VDD_BUFFER1 have the same structure,

providing normal power supply (from 0 to

1.2V). Before each biasing pin will have a

specific VDD_BIAS power supply. Now we

are using one VDD_BIAS for all of them

which make the cirucit simplier and reduce

the circuit size. That’s why our pin number

is reduced from 64 to 56. Also the

VDD_BUFFER1 is used in the buffer stage.

[1]

Figure 20: VDD_BIAS connection

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The circuit schematic of power supply VDD_ S2D in the transmitter is shown in Figure

16. The range VDD_S2D is from 0 to 1.4V because some components perform better under the

voltage, which is a bit higher than the usual voltage (1.2V). The potentiometer is used to adjust

the voltage. The same idea is applied for power supplies VDD_VCO and VDD_DRIVER. [1]

Figure 21: Buffer Stage

The connector supply 3V voltage, but our circuit will only supply 1.2V. It didn’t provide

1.2V after connecting to the connector in version 1.1. So in version 1.2, they added a buffer stage

in transmitter, adjusting the voltage from 3V to 1.2V in our version. We will keep the buffer

stage, but fewer input ports will be used due to our adjustment. However, we still decide to keep

the original connector due to its well performance. So there will be more no-connect ports and

more ports will be connected to the ground. [1]

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Transmitter PCB Layout

Figure 22: Transmitter PCB Final Layout

Transmitter PCB Board

Figure 23: Transmitter PCB Board without Components

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Figure 24: TransmitterPCB Board with Components

Socket Choosing

Figure 25 Our Socket

Figure 26 Our IC chip

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Figure 27: Socket Mechanical Schematic graph

The first step to mounting the socket is to place the base of the socket onto the PCB and

screw in the nylon nuts and bolts, which will secure the socket in place. The next step is to place

the package into the socket. It is highly preferable for the package to have a ceramic lid before

adding the compression plate. The final step is to add the socket lid with the recommended

torque (1.25 in lbs).

Ironwood, the manufacturer of the socket, recommends that the PCB should have a

minimum of 1.6mm thickness with gold plating. If the plating isn’t high enough, you can

manually add some solder paste on the pads to increase the height. The height of the PCB pad

needs to be the same or higher than the solder mask. The PCB designer also has to pay attention

to the fact that the plating is not directly in the center of the socket and that there is a 0.25mm

offset to the right with respect to the center for each of the through hole that secures the socket in

place.

Soldering Process

After we obtained the PCB, the next step required us to solder the components onto the

PCB. There are 2 types of components that required different ways of soldering onto the PCB.

The 2 types of components are surface mount and through hole.

Surface mount components are directly placed onto the PCB, while the through-hole

components require the component’s leads to be placed into holes drilled into the PCB. The

surface mount components are soldered onto the PCB by adding solder paste between the

component and the PCB then heating it with a solder oven.

The through-hole components are soldered by hand using a soldering iron and copper

wire. The surface mount components included resistors, capacitors, IC regulators and test points.

The through-hole components included the switch, potentiometers, VHDL connectors, and SMA

connector.

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Control Signals

Figure 28: Output Pulse Frequency Versus Frequency Control Signal Bits

We use two control signals to control the frequency and width of the output signal. Using

3-bit frequency control signal to create 8 different frequencies to control our output frequency.

The blue line is the designed frequency for each frequency bit and the red line is the actual

frequency versus control signal bits. Bit 001 represents the highest frequency and 111 represents

the lowest shown in the above figure. Our output frequency we got is around 1GHz lower than

the designed results.

Figure 29: Output Pulse Width Versus Width Control Signal Bits

Also a 4-bit control signal is used to control the width of output signals. We set the width

to be increased when bits are set from 0000 to 0111 and then apply the similar trend for 1000 to

1111 bits. Seen from Figure 29, the experimental result is even better than the designed results.

26

Experimental Results

Connectivity, DC voltages and Currents Tests

After adding the components onto the PCB, the first step is to check all the connectivity

among components. After that, we checked all dc voltages. By adjusting the potentiometers, the

test points for the IC power supplies ranged from about 1.2V to 1.7V. The test points of the IC

biasing power supply ranged from around 300mV to 900mV. Check s parameters of transmission

line.

Frequency Modulation

Figure 30: Pulse frequency = 6.2GHz with frequency control signal bits 011


27


With different frequency control bit setting, we got desired output for each bit. The pulse

frequencies are 6.2GHz, 4.8GHz and 3.2GHz with frequency control bit 011, 101 and 111

respectively shown in Figure 30, 31 and 32. With different frequencies, the amplitude of our

output varies a bit. We can achieve pulse frequencies from 3.2GHz to 7.2GHz and the maximum

peak to peak value we can achieve is around 60mV shown in Figure 32. There is about 40% loss

compared to our design due to the mismatch from the transmission line.

Phase Modulation

Figure 33: Phase modulation comparison at 3.2GHz

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Figure 34: Phase modulation comparison with 1.1ns width

In Figure 33, we apply the phase modulation at 3.2GHz and compare the result with

previous one shown in Figure 32. We also apply the phase modulation for the output pulse with

1.1ns width shown in Figure 34. They are perfectly flipped which achieves our expectation.

However there is some loss due to the phase modulation. Phase modulation allows our

transmitter to send using BPSK, which requires a 180 degree phase shift to implement negative

one. In the next IC design for the transmitter, this specific component of the IC circuit will be

improved greatly, which will account for the loss in amplitude after phase shifting.

Width Modulation

Figure 35: Pulse width = 0.38ns with width control bits 0000 Figure 36: Pulse width = 0.68ns with width control bits 0011

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Figure 37: Pulse width = 0.92ns with width control bits 1111 Figure 38: Pulse width = 1.4ns with width control bits 1011

With different width control bit setting, we can achieve different width for each bit. The

width varies from 0.38ns to 1.4ns. The pulse widths are 0.32ns, 0.68ns, 0.92ns and 1.4ns with

width control bit 0000, 0011, 1011 and 1111 respectively. Also the amplitude is barely changed

with different width control bit setting.

Frequency, Width and Phase Modulation

Figure 39: Frequency and Width Modulation for Output Signals

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Using a specific VHDL code, we created an output to show the capacities of our IC chip.

In Figure 39, it shows a general view of frequency modulation and width modulation combined

with and without phase modulation. Section 1 and 2 use 3-bit frequency control signal and

section 3 and 4 use 4-bit width control signal.

In section 1, there are 7 pulses at different frequencies from high to low and we have

shown three of them from Figure 29 and 32. In section 2, applying 180 degree phase modulation

for these 7 different frequencies. The 7 pulses are shifted so that the output is flipped compared

to section 1 shown in Figure 56, 58 and 60.

Each of the 16 pulses have different width shown in section 3 and we have shown four of

them from Figure 35 to 38 in detail. In section 4, the output is shifted compared to section 3

resulting in a 180 phase shifted output with decreasing amplitude shown in Figure 77, 80, 88 and

92.

PSD Spectrum

Figure 40: PSD Spectrum of Sample Sequence With All Frequencies

In Figure 40, the PSD spectrum is included all the frequencies from 3 to 8GHz, perfectly

covers the ultra wideband range. The FCC regulates the maximum dBm allowed to transmit at

these frequencies, which is shown as the red line in the figure above.

We can still get an additional 20dBm strength using an amplifier. By choosing to

randomly choosing the frequency and phase shift of the signal, we are able to reduce the “spikes”

from the PSD. These spikes are shown in the figure below, from frequencies 4 to 5GHz. After

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removing these “spikes,” we are able to amplify the signal greater and closer to the FCC

maximum standard.

Figure 41: PSD Spectrum of Sample Sequence from 4 to 5.5GHz

Shown in Figure 41, the PSD spectrum is from 4 to 5.5GHz, with the lowest and highest

frequencies removed. Specifically, frequencies from3 to 4GHz and 5.5 to 8GHz are removed.

Figure 42: PSD Spectrum of Sample Sequence At Without 4 to 5 GHz

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The PSD spectrum is the lowest and highest frequencies without the 4 to 5.5GHz shown

in Figure 42. This overall result shows that we can get any frequency range we want in the ultra

wideband range, which is very useful property in the application.

Power Consumption

Figure 43: Plot of Power Consumption versus Data Rate

The power consumption for our IC chip is really low shown in the figure above. As the

data rate increases, the power consumption increases proportionally. The power consumption

and data rate relationship is approximately linear. We have approximately 1.8mW at 2.5MSps

and 7.3mW at 17MSps.

S-parameters of Transmission Line

The Figure 44 shows the transmission line parameters S11. The black line is the desired

results, while the green line is with no inductor, red with 1 inductor and blue with 2 inductors. As

shown in the figure, the best results were with no inductor.

The PCB transmission line S11 parameter is slightly shifted to the right by 3-4 GHz from

the ideal transmission line. This is the problem why our amplitude of the output signal is very

low. The S11 parameter shows that the transmission line on the PCB is losing the majority,

approximately 70% lost, of the signal between 3-6GHz, which is the desired frequency of our

signal. Later, we will show a newly designed transmission using expensive PCB material from

Rogers.

33

Figure 44: Plot of S11 of Transmitter

Figure 45: Plot of S11 of Transmission Line

The S12 parameter of the transmission line is shown above. The black line is the ideal

S12 parameter and the most similar line is the green line with no inductor. The value of S12 is

the same as S21 and the value of S11 is the same as S22.

Improvements

Because of the large shift in our previous transmission line design compared to the

desired result, we decided to design another PCB transmission line with Roger. The figure below

show the improvements of the S parameters. The red line shows the Roger’s S parameter

compared to the blue line, which is the original transmission line.

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Figure 46: Plot of S11 of Improved Transmission Line

Figure 47: Plot of S12 of Improved Transmission Line

The S11 of the Roger’s PCB transmission line is shown in Figure 47. The Roger’s S11

parameter is a lot better than our original transmission line especially around the 3-6GHz

frequency. There is less loss in the transmission line around our desired frequency. Overall, as

shown, the Roger’s PCB has a much lower S11 compared the original PCB, which means there

is much less reflection of the input. As for the S12 parameter, the Roger’s PCB is above the

original PCB S12 parameter. This means much more of the signal is sent through the

transmission line. Around 3-6 dB, there is approximately a 3 dB difference between the two

PCB’s. The transmission signal is increased twice the amount because it’s a logarithmic

function.

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Figure 48: Transmission line comparison

Seeing from the output comparison for original transmission line and Roger’s

transmission line in Figure 46 and 47, the Roger’s transmission line creates a much larger

amplitude than original one by around 65%. We reapply all the tests with Roger’s transmission

line and all outputs are similar expect they have much larger amplitude.

Impact on Society and the Environment

With the growing need for wireless sensor network applications such as healthcare,

agriculture, environmental monitoring and industry, there has been an increasingly large amount

of research done in ultra low power, ultra wideband impulse radios. Impulse radios are ideal for

low power and low data rate applications such as various wireless medical monitors. [1]

There will be many benefits to society to be able to have cheap low data rate, low power

consumption wireless transmitters and receivers. The main improvement in quality of life is

getting rid of the need of direct wire connections for simple applications such as a wireless

mouse, keyboards and cellphone to cellphone data communication. There are countless

applications that could benefit from the ability to transfer data wirelessly using ultra low power.

Essentially, our ultra wideband impulse radio will benefit multiple aspects of society and

contribute to various industries in unique ways. [1]

From a medical perspective, we will be able to add various wireless sensors on patients,

while monitoring them. The sensor could be monitoring patients during complicated surgeries,

ensuring all the vital parameters are in their acceptable regions. Another application aspect could

be in medical research. The sensor could be collecting data on a patient in his or her home

36

environment for a long period of time, since the device would be ultra low power. One example

of a sensor would be a pacemaker, which many now days are able to communicate wirelessly to

a computer. There is an increasing need for small low power electronic devices that are required

to be implanted into the human body to monitor and collect data on the patient. Our ultra

wideband impulse radio will benefit the medical industry in a very potent way. [1]

Similarly to the medical industry, the agricultural portion of society will also benefit from

low power ultra wideband impulse radios in a similar fashion. Farmer’s will be able to monitor

difference aspects of their livestock by implanting wireless sensor devices to collect information

on the wellbeing of their animals. There are multiple scholarly articles about how wireless

transmitters are attached to cows, to determine a pattern on how cows graze on a grass field. It

can also be used to monitor endangered species that need protection by sending data to

researchers at the zoo. The rare spices will have to be in a case unfortunately, due to our short-

range wireless transmission. There could be different kinds of sensors on the animal such as

heartbeat, amount of activity, blood pressure, nesting areas and grazing areas that could then be

transmitted through a wireless transmitter such as our IC chip. [1]

Environmentalists that monitor natural phenomenon will also benefit from having cheap

low power wireless devices that collects data on the weather. Essentially, similar to how the

medical and agriculture industries use wireless transmitters for collecting data, environmentalists

could also have some sort of rain, wind, humidity, UV radiation and other sensors, which can

then be sent using a wireless transmitter to a computer. Some advantages to not having wire-

lined sensors, is the ability to move the sensor around without the need of extending or

shortening the wire. [1]

In conclusion, having a low power small wireless sensor has huge benefits to society as

well as improving the quality of life in many industries. Our project as a whole has the potential

to help improve society and the environmental simultaneously on a large scale. [1]

37

Report on Teamwork

As there are only two member for this design project, the project was done together as a

team for every step of the project. Since the group size was so small, there was not a need to

delegate works to each member as an assignment. We did the majority of the project together as

a team, similar to EC2 lab.

For design project 1 and 2, we have collaborated great as a team. Each member

contributed approximately the same amount. We’ve took numerous hours learning the PADS9.5

software with our fellow graduate student. We completed 3 months’ worth of tutorials given by

UQAM in approximately 1-2 weeks. These tutorials included creating schematics that were not

related to our IC, but purely for the purpose of learning the software such as generating the

netlist, bill of materials, design rule checks, importing the netlist into layout, and various other

tricks. As well as looking at our IC chip and understand all the aspects of the chip, whether it be

the datasheets, figuring out what each component is and how it works. Before actually being able

to do the PCB schematic and layout, we had to understand completely all the devices on the PCB

as well as the input and output pins of our package. After learning the software, we were also

given multiple theoretical explanations from our graduate student about how our IC specifically

implemented the types of modulations described in the background chapter. [1]

One of the major difficulties was actually finding a socket for our PCB. Many companies

didn’t have the specific socket we need for our package specifications. However, we did find 5

companies that provided our sockets after days of research, contacting them through email.

Approximately only 3 companies replied and of the 3 companies 2 of them demanded a quota of

5 – 10 sockets per order, each $350. The company that didn’t demand a quota, Ironwood, still

asked for $280 for a socket, even after a 30% discount for educational purposes. The price was

simply too high, so we ended up not using a socket. The socket datasheets are shown in the

appendix. [1]

Some of the difficulties will be learning how to solder, getting familiar with Spartan 6,

combining the whole test setup (IC, package, PCB, FPGA, computer). [1] For design project 2,

we spent most of the time putting everything together. We both took turns soldering all the

components onto the PCB as well as the ceramic lid onto the package. We spent a large amount

of time trouble shooting our PCB and getting everything to work. We had major problems with

our PCB because components kept breaking such as IC regulator or potentiometer. We also had

to add solder to many of the surface mount components due to a lack of contact with the PCB.

We had to use 3 packaged IC chip to obtain all our results. One of the hard parts was that

there was no signal coming out from the IC chip, which was very difficult to debug, since we

were not sure if it was the VHDL, PCB connection or the IC chip itself.

After we got the IC chip to transmit a signal, the next part was very long. We had to

obtain all the graphs and data from our IC chip. As you can see there are many graphs we had to

obtained that are included in the Appendix, showing the capabilities of our IC chip. The graphs

had to be modified using Matlab to get the scale, labels and legends for each graph correct.

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Lulan has been responsible for the Poster, Matlab graphs for final report, oral

presentation, testing the IC chip. George has been responsible for the Poster, oral presentation,

writing the final report, progress reports, testing the IC chip, soldering, choosing the socket.

Conclusion

In conclusion, we have learned a tremendous amount of material on UWB theory, the

process of implementing a IC chip onto a PCB and testing the chip. We have been able to

successfully design and implement a low power UWB IR transmitter that is capable of three

different types of modulations: frequency, width and phase modulation.

Having the capability of those three types of modulation allows our transmitter to be able

to transmit using OOK, PPM and BPSK. We have learned many technical skills in implementing

an This project has been very rewarding and will be tremendously useful in pursuing a future in

microelectronic.

We have developed many skills such as soldering, designing a PCB, testing an IC chip as

well as many other invaluable skills. This design project will give us needed experience to dive

into the microelectronic industry. Our project has been incredibly successful, considering that

our IC chip could have not worked at all. We are grateful for this opportunity to work with such

intricate microelectronics.

References

[1] G. Lee and L. Shen, “Ultra Wideband CMOS,” McGill University, Montreal, QC, CA. April

2014.

[2] Integrated Defense Staff of India. (2010.) Ultra Wide Band for Wireless Communications.

[Online] Available: http://ids.nic.in/tnl_jces_mar_2010/uwb.htm

39

Appendices

Data Sheet of the IC

Table 2 Datasheet of IC

Name #IC #TX #RX Type Description

VDD_N 1 1 PWR Power supply TX

VSS_N 2 2 GND Power supply TX

VREFC<1> 3 1 BIAS Minimum voltage reference for ADC

VREFC<7> 4 2 BIAS Maximum voltage reference for ADC

TX_B<0> 5 3 CFG Frequency configuration


VB2_LNA 7 3 BIAS

VB1_LNA 8 4 BIAS


TX_S 10 6 IN Sign of the bit to be transmitted

VDD_LNA 11 5 PWR Power supply LNA

VSS_LNA 12 6 GND Power supply LNA

RX_IN+ 13 7 RF Positive input of the receiver

LNA- 14 RF Negative test LNA output

LNA+ 15 RF Positive test LNA output

RX_IN- 16 8 RF Negative input of the receiver

VSSI 17 9 GND Power supply integrator RX

VDDI 18 10 PWR Power supply integrator RX

TX_MOD_CLK 19 7 IN Clock pulse repetition

TX_PC 20 8 IN Signal management power cycling

VSS_PreA 21 11 GND Power supply RX preamplifier

VDD_PreA 22 12 PWR Power supply RX preamplifier

TX_A<3> 23 9 CFG Configuration of pulse length TX


VSSD 25 13 GND Power supply RX

VDDD 26 14 PWR Power supply RX



VrefCMP- 29 15 BIAS Reference negative comparison

VrefCMP+ 30 16 BIAS Reference positive comparison

VB_DRIVER 31 14 BIAS Biasing driver 490 mV

TX_DATA_IN 32 15 IN Data to be transmitted

SEL_PREA2 33 17 CFG Activates the second pre-amp

RX_OUT<3> 34 18 OUT Receiver output

VSS_DRIVER 35 16 GND Power Driver TX

VDD_DRIVER 36 17 PWR Power Driver TX



TX_OUT 39 18 RF Transmitter output

TX_OUT 40 19 RF Transmitter output

VSS_CLEAN 41 20 GND Reference mass TX

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VREFI 42 21 BIAS Reference mass integration

VSS_VCO 43 21 GND Power supply VCO TX

VSS_VCO 44 22 GND Power supply VCO TX

VDD_VCO 45 23 PWR Power supply VCO TX

VDD_VCO 46 24 PWR Power supply VCO TX

RX_CTRL_CLK 47 23 IN Control signal integration

RX_PC_ON 48 24 CFG Activate power cycling of the receiver

VSS_S2D 49 25 GND Power supply S2D TX

VDD_S2D 50 26 PWR Power supply S2D TX

VB750 51 25 BIAS Biasing RX 750 mV


VB1_S2D 53 27 BIAS Biasing S2D 920 mV

VB2_S2D 54 28 BIAS Biasing S2D 550 mV



Frequency modulation without phase modulation

The follow graphs is the frequency modulation capabilities of our UWB transmitter. The

following graphs shows the output with frequency control bits 2 to 7, which corresponds to

frequencies from 6.5GHz to 3GHz. The control bits and its frequency graph are shown at the end

of the “Design and Implementation” section.

Figure 49: Pulse frequency with frequency control signal bits 010

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Figure 51:Pulse frequency with frequency control signal bits 100

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Frequency modulation with phase modulation

The following graphs is the frequency modulation combined with the 180 degree

phase shift. These graphs are obtained using frequency control bits from 2-7. The

graphs are the same as the ones shown in the previous section, “Frequency

Modulation without phase shift,” except they are 180 degree phase shifted. There is a

little bit of loss of amplitude when phase shifted.


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46


Width modulation without phase modulation

The following graphs shows the width modulation without phase shift of 180

degrees. These graphs are obtained using control bits 0 to 16. The relationship of the

width control bits and width of the signal graph is shown in the end of the “Design

and Implementation” section.

Figure 61: Pulse width with width control bits 0000

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Width modulation with phase modulation

The width modulation with phase modulation are shown in the graphs below with control

bits from 0 to 16. Essentially, these are identical graphs to width modulation without phase

modulation, except they have a 180 degree phase shift.


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Design Project 2 Final Report

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Transcript of Design Project 2 Final Report