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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.

The ladder

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.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
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?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Source:  OpenStax, R/2r implementation of a d/a converter. OpenStax CNX. Dec 17, 2014 Download for free at http://legacy.cnx.org/content/col11732/1.1
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