Alpha Eritrean Engineers Magazine 2013 August Issue

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AEEC | August 2013 1

CONTENTS AND CONTRIBUTORS

CONSUMER DEFINES V ALUE

BY ERMIAS K AHSAY

LOW POWER CLOCK MULTIPLIER DESIGN FOR

HEART RATE MONITORING SYSTEM

BY TEMESGHEN TEKESTE

MY TO DO LIST

BY S AMSON GONNETZ

JOB OPPORTUNITIES

BY FILIPOS ABRAHAM &

..

Y OSIEF

WOLDEMARIAM

EDITORS

SEBLE GEBREMEDHIN, M.S. IN

PSYCHOLOGY

ADIAM WOLDEGERGISH, PH.D IN

MOLECULAR BIOLOGY

S AMSON GONNETZ, B.A. IN CIVIL

ENGINEERING

FILIPOS ABRAHAM, M.S, IN SOFTWARE

ENGINEERING AND

Y OSIEF WOLDEMARIAM, B.A. IN

ELECTRICAL ENGINEERING




Consumer Defines Value

Ever since I was young, I was interested inelectricity, electrical circuits and gadgets. Growing

up I always wished to alleviate the power shortage

that our society, Developed and specially

Developing Countries, faced and wished to

improve the quality of life through technology.

After migrating to Centralia which is in

Washington State I initially attended a community

college to receive an associate degree in general

engineering.

Soon after completing my associate degree, I

realized how quickly modern technology was

changing and decided to continue my education. I

enrolled at Oregon State University (OSU) in

Corvallis, Oregon and completed my degree

focusing on electrical and computer engineering,

specializing in semiconductor processing and

manufacturing. During my third year at OSU, I

worked with a company called Planar Systems,

which manufactures medical, industrial and

commercial display. While working at the

company,

I did research looking at thin film

(Electroluminescent) and light emitting diode (LED).

The focus of this research was to discover which ofthese two electronics products would be better for

back lighting on computers, televisions and mobile

devices. As part of my research, I looked at Thin film

electronic circuitry components that are etched onto

a thin wafer of silicon.

Thin film transistor liquid crystal display circuits

which are made on a thin layer of specially

formulated silicon applied to a glass plate. Each TFT

LCD, Thin-Film-Transistor Liquid-Crystal-Display,unit contains the transistors, wiring and other

components necessary to turn an LCD on or off,

blocking or releasing light. Colors are thus produced

with built-in color filters. Light Emitting Diodes

(LED) is specially formulated semiconductors that

produce light when their electrons are prompted

into moving from a high-energy state to a lower one.

Light is, as a result, produced with much less energy

than light bulbs or CRT’s, Cathode Ray Tube- a

vacuum tube containing one or more electron guns

(a source of electrons or electron emitter) and a

fluorescent screen used to view images. Like TFT

LCD’s, LED displays can contain thousands of units

working together to form an image. Individual LED

units can be colored and you can control the

brightness of LED displays in the same way you can

dim a light bulb. At the conclusion of my research, it

is evident that LED for backlights improves the

quality of display color and image contrast




compared to thin film. LED backlights also allow

thinner display packages, more tolerant viewing

angles, less energy consumption and longer product

life. As seen today, products that use LED’s such as

flat panel LCD and LED TV’s, mobile devices,

calculators, and other medical and commercial

products dominate the market presently.

After completing my study at OSU, I worked as a

product engineer in marketing and sales branch

interacting directly with consumers to find out what

requirements and needs were present in this fast

growing technology sector. While I was working in

marketing, I began to research and work on my Lean

Six Sigma which is a set of tools and strategies for

process improvement, or a powerful, proven

method of improving processes efficiency and

effectiveness that focuses customer satisfaction.

During my research, I discovered a partner that had

the same interest in Lean Six Sigma. We bother want

to help customers get products they need as fast as

possible and with full customers satisfaction. To do

this, both my partner and I created an enterprise

called Lean-Agile SERVICES INTERNATIONAL (LSI).

Lean-Agile is a business strategy based oncustomer satisfaction and delivering quality

products and service that are: 1) Exactly what

the customer needs, 2) When the customer

needs the product, 3) The amount the customer

requires, 4) Based upon an agreed price and

5)Accomplished with minimum resources.

The term 'Lean' in a business or manufacturing

environment describes a philosophy that

incorporates a collection of tools and techniques

into the business process to optimize time, human

resources, assets, and productivity, while

improving the quality level of products and

services to the customers. Lean is also a principle

that creates and maximizes value through the

elimination of waste. Organizations thus rethink

their end-to-end value chains and find ways to

provide what their customers value better, fasterand with significantly fewer resources than their

competitors and can obviously develop an

unassailable competitive advantage by utilizing the

Lean principle.

My partner and I, further developed and are able to

offer what we believe to be the most effective,

powerful, user friendly, and affordable lean data

management software called Lean Data System

(LDS) or Supplier Quality System. LDS is developed

as a primary tool designed to promote a truly lean,

effective and uniform supplier quality effort. It is

also meant as a single source of supplier quality

issue details, lessons learned, and data to support

key metrics used to identify what issues and




concerns suppliers need to address and in what

order based on cost and schedule impact or both.

Lean Data System helps companies identify and

resolve their issues within a fraction of the time.

LDS allows companies to focuses on what matters

the most, Safety, Quality, Cost and Schedule inorder to give the best service and product to the

consumer. The essential idea of our company

(LSI) is to maximize customer value while

minimizing waste.

Lean creates more value for customers with fewer

resources.

At the end of the day, companies, large, medium or

small, who will be using this fast growing

technology, will be defined by their customers, the

value of their products and services.

~ Engineer Ermias Kahsay

A

E

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Bringing the best and the brightest together

Hard to reach doesn’t have to mean hard to do




It is every one's dream to connect and discuss as Eritrean professionals are

spreading to all corners of the world as if to fill the map. As its name

indicates Alpha Eritrean Engineers Magazine is the beginning to motivate

other professionals outside engineering to find a means of connection. It is a

brilliant idea to be Alpha.

There is no green light ready to welcome any one whenever you live abroad.

Hunting professional job is the most challenging. I admit that being focused

and working hard will change Eritrean Diaspora's life sooner or later. But

Alpha Eritrean Engineers Magazine is in the right track and wish to

congratulate those who initiate the idea.

Estifanos Asrat Geotechnical engineering

Thanks for sharing brother. It’s so up lifting to see Eritreans in such a

diverse and intellectual field. I am not sure if the magazine is distributed

and how many copies are printed but since I am in the printing industry,

anything I can do to be any assistant to you and your peers, please, don’t

hesitate to let me know.

Dr. Awet Gherezghiher

ALPHA ERITREAN ENGINEERS

Comments & Suggestions

Page

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Background

Born and raised in the capital city of Eritrea, I

completed all my studies including myundergraduate degree in Asmara. I received my

Bachelor of Science degree in Electrical Engineering

from University of Asmara. After I completed my

studies, I joined the Eritrea Institute of Technology

and worked as Graduate Teaching Assistant. While

working, not only did I have the opportunity to learn

the challenges of Electrical Engineering but I also

gained experience within the academic sector.

Although my interest in Electrical engineering goes

back to my childhood, during my undergrad studies, I

developed a specific interest in digital electronicsand was eager to advance my studies. Thus, from

September 2010 to May 2012, I studied

Microsystems in Masdar Institute of Science and

Technology and took numerous course related to

circuit design and microelectronic fabrication.

I was very fascinated and encouraged to do research

in circuit design after I successfully designed and

tested a chip during my graduate research work. My

research involved digitally assisted analog/mixed

signal circuit design.

I was exposed to the challenges of designing an

verification of custom analog and digital circuits. CA

tools from Synopsys, Cadence and Mentor graphic

were extensively utilized while working on a chip

My research was to implement an ultra-low powe

clock multiplier to supply a LED driver with a 2MHclock based on a 32 kHz reference. The circuit wa

part of an ultra-low power heart rate monitorin

system which uses pulse oximetry technique. Th

system comprises of a photon to digital converter

LED driver and clock generator, (Figure 1). Thre

chips were designed and fabricated and it was a

inspiring experience to design and test a chip a

masters level. One of the outcomes of the researc

conducted was presented at the International Soli

State Circuit Conference (ISSCC 2013) [1]. Being par

of the research group, I had the privilege tparticipate in the ISSCC 2013 conference which waheld on February, 2013 in San Francisco. I also fullcustom designed chip to appear in the conference from

the Middle East region.

Figure1

Heartrate monitoring system based on pulse

oximetry

The novel aspect of the clock multiplier is that it ha

digital intensive implementation based on Frequency Locked Loop (FLL) architecture whic

allows operation at 0.5V supply voltage with les

than 10 micro Amps of current consumption.

Low power Clock multiplier design for heart rate monitoring




Power consumption is crucial in low power CMOS

circuit design especially for portable and mobile

devices. Scaling the supply voltage is one of the best

techniques to lower the power dissipation. That is

why the systems power supply was limited to 0.5V.

Another reason is that this voltage is also available

directly from a tiny solar cell. The problems

encountered when designing clock generators at lowsupply voltage is the susceptibility to process,

temperature and supply voltage (PVT) variations.

The designed clock multiplier is robust in the

presence of process, temperature, and supply voltage

variations while avoiding complex calibration oranalog circuits such as band gap voltage references

(Figure 2). It is an integer N-frequency multiplier

based on a Frequency Locking Technique. The main

distinction between Frequency Locked Loop and

Phase Locked Loop is that in FLL the error signal

generated in the loop represents frequency rather

than phase error. In case of PLL the error signal

would be proportional to phase. Generally the

system could be described as a negative feedback

system in which a change in the output frequency

would be counteracted by the restoring behavior ofthe feedback.

The main parameter tracked in the feedback loop i

the frequency of the output clock. The system

constantly keeps track of the output frequency an

generates an error signal by comparing it with

reference word. The system does frequenc

multiplication given by FOUT = FREF N where FREF i

reference frequency, FOUT is the output frequenc

and N is an integer.

Figure2

Architecture of the designed FLL

The forward path of the loop comprises of the digita

comparator followed by a set of filters and a digitall

controlled oscillator. The feedback path is formed b

a frequency detector which generates a digital wor

equivalent to the frequency of the output of the DCO

The frequency detector is analogous to a divider tha

generates a phase equivalent to the output in digitaphase locked loop. Digital circuits were heavil

utilized when implementing the system. Digita

circuits are immune to PVT variations as they onl

have to determine digital logic levels of 0 or 1. Wit

technology change the digital circuits could b

retained. The analog part in the design was th

Digitally Controlled Oscillator, and this part might b

required to be redesigned when moving to anothe

technology.

The FLL is designed to generate a clock wit

frequency of 2.096 MHz generated by a digitally




controlled oscillator (DCO) as revealed in Figure 2.

The DCO is formed by a digital to analog converter

(DAC) and a current controlled ring oscillator. It is

controlled by a 31 level thermometer coded word.

The thermometer code essentially controls a set of

PMOS switches of the DAC, and by turning on or off

more switches the output phase and frequency of the

DCO is modulated. Since the system is designed tokeep track of the output frequency, a frequency

detector (FD) based on counters is implemented. The

frequency detector counts the number of full cycles

of output clock in one period of the reference clock.

The output of the frequency detector is a 9-bit word

and is added with a reference control word so as to

generate a frequency error signal. A value 32 is

chosen as a reference word that corresponds to the

number of full cycles of 1.048 MHz output clock in

one period of the reference clock with frequency

32.768kHz (note that this frequency is available froma commercial crystal oscillators). The 1.048MHz

signal is obtained by dividing the 2.096MHz clock

from the DCO.

The frequency error is accumulated and filtered to

tune the DCO to the desired frequency. The first

accumulator followed by an adder form a lead lag

filter. In addition to accumulating the error signal the

lead lag filter helps reduce the in band phase noise

and quantization error. The output of the lead lag

filter is fed to a second 18bit accumulator. The

output of the accumulator drives a first order Sigma

Delta modulator. The Sigma Delta modulator has an

input of 18bits and output of 5bits. By its dithering

behavior, the Sigma Delta provides a digital word

with average value that tracks the input 18bit word.

Prior to driving the DCO, the 5bit binary word from

the Sigma Delta is converted to a thermometer code.

The binary to thermometer decoder has a behavior

to change only one bit when its input changes by

only one value, thus insuring monotonicity. The DCOhas a CCO which integrates the filtered control signalto an output clock phase ( ).

All the clock signals All the clock signals that operate

the logical circuits are obtained from the referenc

clock and the output of the DCO. The Sigma Delta i

made to run at a higher frequency from the output o

the DCO to enhance the noise performance of th

system. Synchronization circuits are added in th

system so as not to lose any information when th

signals are traveling across the loop.

In summary, proposed system was PVT toleran

frequency locked loop based clock multiplier fo

heart rate monitoring system operating at ultra-low

power. All the circuit required were simulated at

transistor level and the circuit layout was created. A

chip was fabricated and tested. A test board wa

designed as shown in Figure 3a below and the outpu

of the chip is shown in Figure 3b and 3c. The chip

had the desired performance with results similar t

the post layout simulations. Furthermore, aimportant tool that was used in developing thi

model system is called CppSim (www.cppsim.com

which offers fast behavioral simulation systems. It i

built in c++ based modules and various user define

modules can easily be integrated into its platform

This tool is helpful for Electrical Engineers especiall

those working in circuit design.

Figure 3a

http://www.cppsim.com/






The tool is called CppSim (www.cppsim.com) which

offers a fast behavioral simulation of systems. It has

built in c++ based modules and various user defined

modules could be easily integrated in to its platform.

It is a helpful tool for Electrical Engineers especially

for those working in circuit design.

Figure 3b

Figure 2b

Figure 3c

References

[1] Alhawari M. et al, “0.5V <4µW CMO

photoplethysmographic heart-rate sensor IC based on a nonuniform quantizer”, ISSCC 2013, Sanfrancisco, CA.

~ Engineer Temesghen Tekeste

Simple facts

The first electric light was made in 1800 by Humphry Davy , an

English scientist. (wiki.answers.com)

Three new and latest mathematical theorems were developed by

an Eritrean high school student Saied Mohammed Ali , who was a

student at Warsay – Yekealo Senior Secondary School. (TesfaNews)

An early form of circuit breaker was described by Thomas Edison

in an 1879 patent application. (Wikipedia)

The compass, a tool used to help aid in finding direction, was

invented in China, during the Han Dynasty between the 2nd

century BC and first century AD. The first compasses were made of

lodestone, a naturally magnetized ore of iron. William Sturgeon

invented the modern compass, which is still used today.

(Wikipedia & invention.yukozimo.com)




http://inventors.about.com/library/inventors/blelectromagnet.htm






AEEC | February 2013 10

A land of dreamers who walk confidently

in the direction of their dreams

Eritrea purely magnificent

Civil engineering at its best!




My To-Do Lists

Each day, most of us have personal goals-say,

preparing for an exam, throwing a house party or

going somewhere to attend a family weeding etc, and

we have different techniques of managing our time to

increase our productivity, but at certain point it becomes so difficult that the tasks pile up and with

never ending task lists you tend to procrastinate and

frustrate.

I have a problem with my to-do list. Do you?

Even though I had a difficulty with organizing my

day; I always have a to-do list. I find that if I write

my tasks down, I'm far less stressed because I

know I won't forget anything. It helps me to set

priorities and when I'm done with one task, I canmove right onto the next.

I fall in to all kinds of traps with my to-do lists. I

have lists all over the place. I put short and long

time lists and when I occasionally review them

with my pen against the finished ones I found most

of them are not done or partially done. And the

feeling that I wasn't accomplishing anything

frustrates me some times.

For instance, I always plan to start my day bywaking up at six in the morning, go to Gym or do

some running and then do the rest according to my

to-do lists. But I found walking up at six is really

difficult for me. I've been struggling with this for

years. I don’t know why it is always in the first of

my to-do lists. I know I am not going to wake up

but I write it as my first morning task. Why bother

when I can't do it?

In the morning I think that I can do all my to-do

lists for the day. Once I start checking my e-mail I

get distracted and I spend more time on some o

the tasks that are not listed. So, something goe

wrong with my today’s tasks.

Consequently I can't finish my to-dos and I feel likI haven't done enough for the day. On the othe

hand, there are days that my to-do lists goes we

and I feel that I achieved something and I fee

contented. It boosts me to do more for the nex

day.

I’m more organized at work than at home or mor

productive outside than at home. More organize

when I am doing some other people’s busines

than my own. If cleaning or organizing my home ione of my short to-do lists, most of the time

procrastinate to do it unless someone is coming t

my house. I am sure most of us do, especiall

single people homes are more clean and organize

when they invite someone.

I think keeping your lists fairly short helps manag

your tasks easily. It’s so disappointing at the end o

the day when I see my to do lists with a number o

items on it has only a few or maybe non

accomplished. Being able to manage small achievmore makes me very happy. It works for me and

hope it will work for you too!

~ Engineer Samson Gonets

“Only put off until tomorrow what you

are willing to die having left undone”

― Pablo Picasso

http://www.goodreads.com/author/show/3253.Pablo_Picasso





AEEC | February 2013 12

Engineering-Humour.com

Glass Half Full

Someone who sees a partially filled glass as half full is an

often cited definition of an optimist. Someone who sees

the same glass as half empty is taken to be a pessimist. Ithas been said that someone who sets the glass as poorly

designed, because it is twice as large as it needed to be,

is surely an engineer .

……. Sense of humor from engineer’s prospective




Alpha Eritrean Engineers Magazine

A E E M




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The authors

Ermias Kahsay [email protected]

Received AS from Centralia community College in

General Enginering in 1994 & BS from Oregon

State University in Elecrical, Electronics and

Computer Engineering in 2002. Currently he

owns company (business) called Lean Services

International works as senior consultant and

President of Operations.

Temesgen Tekeste [email protected]

received his B.S. in Electrical Engineering from

University of Asmara & MS in Micro-systems in

Masdar Institute of Science and Technology, Abu

Dhab. Currently he is employed by Masdar Istitute

of Science and Technology as a research engineer.

Samson [email protected] received his B.S. in CivilEngineering from San Francisco State University in

California and currently he is studing and in a

process of abtaining a Professional Engineer

licence (PE).

If you need an updated information,

discussions or got an Engineering

experiences that you want share

your knowledge or ideas with your

fellow professionals.

You will find us on

www.linkedin.com/groups/Alpha-

Eritrean-Engineers-Community

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IT INFORMS

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