# 0.2 Motivation

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A summary of our motivations and choices for this topic.

## D/a conversion

We were interested in this project because we wanted to explore the science and practicality behind D/A conversion but also to learn from the hardware/software interactions afforded by the BeagleBone Black. We wanted to take a stored digital signal and take it through the D/A conversion process primarily for the purpose of teaching others and learning ourselves. This process is enormously important in the world of contemporary technology and we are executing a novel process with this specific BeagleBone black. Controlling hardware/software interactions is integral in the design process for many electronics, so we wanted to incorporate this as well.

## Why choose the r/2r ladder?

Since we are using 8 bits to quantize our signal, an overall effective D/A converter that changes our digital signal to analog is the R/2R ladder. As discussed earlier, an R/2R ladder is a binary-weighted converter that uses resistors of only two different values: R and 2R (the actual values are insignificant, what matters is the 2:1 ratio). These resistors are cascaded together in the structure below, allowing for the output voltage to be a weighted sum of the input voltages.

Although there are other ways to implement a D/A converter, for digital signals of 8 bits or less the R/2R ladder is one of the best options. Some of the advantages of the R/2R ladder is that it is composed of only resistors of two different values, allowing it to be very easily implemented on a small-scale at a low cost (small resistors of specific values are can be cheaply produced). Some potential drawbacks of using an 2/2R ladder is that with longer ladders, the cumulative capacitance of the system could potentially delay the transmission of the signal as it is converted from digital to analog. However, since we are using 8 bit signals, there are only 8 rungs on our ladder, so there is no significant delay time due to the capacitance. Another potential problem with R/2R ladders in general is that with the more significant bits, the precision of the resistors are increasingly important. A small fluctuation in these resistors can completely overwhelm the output values of the smaller bits. Fortunately for us, since there are only 8 rungs in the ladder, only so much precision is required for our resistors in the most significant bit.

## Why choose rc low pass filter

After a digital signal is converted to analog, its amplitude is still quantized. Before it can be outputted as a continuous signal, its amplitude must be smoothed out between the different values. In the frequency domain, this is effectively low-pass filtering the signal. Although there are many different ways to implement a low-pass filter, we decided for our project that the most efficient way would be with a simple RC circuit. Like the R/2R ladder, a basic RC circuit can be implemented very cheaply and on a small scale, since it is composed of only a resistor and a capacitor. Since it is also very simple, our signal can propagate through it very fast. There is one potential problem with the RC (first-order) low-pass filter is that it attenuates more slowly than higher order filters, therefore not completely removing out higher frequencies. However, since the human ear cannot hear above 20,000 Hz, this is not a problem for our implementation. We just require a filter good enough to remove the majority of the higher frequencies so as to not waste power and potentially damage the speakers, as well as to smooth out the different quantized levels in the time domain. A simple RC low-pass filter serves that purpose.

Although there are other ways to implement a D/A converter, for digital signals of 8 bits or less the R/2R ladder is one of the best options. Some of the advantages of the R/2R ladder is that it is composed of only resistors of two different values, allowing it to be very easily implemented on a small-scale at a low cost (small resistors of specific values are can be cheaply produced). Some potential drawbacks of using an 2/2R ladder is that with longer ladders, the cumulative capacitance of the system could potentially delay the transmission of the signal as it is converted from digital to analog. However, since we are using 8 bit signals, there are only 8 rungs on our ladder, so there is no significant delay time due to the capacitance. Another potential problem with R/2R ladders in general is that with the more significant bits, the precision of the resistors are increasingly important. A small fluctuation in these resistors can completely overwhelm the output values of the smaller bits. Fortunately for us, since there are only 8 rungs in the ladder, only so much precision is required for our resistors in the most significant bit.

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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