Digital Electronics Basics - Chapter 6: Analog to Digital & Digital to Analog Conversion
Publish Date: Mar 27, 2013
Overview
The Digital Electronics Basics series present the fundamental theories and concepts taught at entry level electronics courses a
both 2 year and 4 year institutions. This series of content provides examples to professors to enable them to easily teach conce
to students, who can develop a solid underlying knowledge of digital electronics using NI solution. This series focuses on some
the basic theory as well as providing the NI Multisim circuits to enable practical implementation and experimentation as homew
for students.
Table of Contents
1.
2.
3.
4.
5.
6.
7.
8.
In this Chapter
Example Courses
Analog to Digital Conversion
Example Circuit
Digital to Analog Conversion
Example Circuit
NI Suggested Solution
References
1. In this Chapter
We begin this chapter by studying the analog to digital and digital to analog conversion and understanding the fundamentals. T
we examine two example circuits which can be used by any educator or student to verify our results using NI Multisim.
If you do not have NI Multisim installed on your computer you can download a free 30 day evaluation at
http://www.ni.com/multisim/try/ (http://www.ni.com/multisim/try/)
2. Example Courses
Listed below are example courses that teach this concept at their schools.
Course Name
School
Learn More
Digital
Electronics
Basics
Macomb Community http://www.macomb.edu/noncms/search/courses/coursekey.asp?coursekey=ELEC-121
College
Digital Circuits Henry Ford
I
Community College
https://my.hfcc.edu/site_manager/Catalog_Manager/courses/view_course1.asp?id=215
Digital Circuits Henry Ford
II
Community College
https://my.hfcc.edu/site_manager/Catalog_Manager/courses/view_course1.asp?id=217
3. Analog to Digital Conversion
An ADC is used to convert varying analog signals such as voltage to a digital signal consisting of 0s and 1s [1].
Let’s consider a basic ADC with 4 outputs, we can see that the range of 4-digit binary numbers that this ADC can produce is as
follows:
[1]
And therefore the ADC will convert the analog voltage signal into a 4-digit digital output as shown below:
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[1]
Let us now implement an analog to digital conversion circuit and observe our findings and compare to the theory above.
4. Example Circuit
STEP 1: Using NI Multisim, open circuit file “adc.ms12”. You will see the circuit below:
STEP 2: Run the simulation, then use "A" and "Shift-A" on your keyboard to change the position of the wiper on the potentiome
Observe the changes on the display and the LEDs.
Note: The ADC has an input range of +/-10V. The output ranges from 00 to FF.
5. Digital to Analog Conversion
A DAC is used to convert digital signals consisting of 0s and 1s to varying analog signals (such as a voltage signal) [1].
Let us consider a basic DAC with 4 inputs, we can see that the range of 4-digit binary numbers that this DAC will have as input
and the corresponding decimal output range are as follows:
[1]
And therefore the DAC will convert the digital input signal into a varying analog output signal as shown below:
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And therefore the DAC will convert the digital input signal into a varying analog output signal as shown below:
[1]
Let us now implement a digital to analog conversion circuit and observe our findings and compare to the theory above.
6. Example Circuit
STEP 3: Using NI Multisim, open circuit file “adc_dac.ms12”. You will see the circuit below:
We modified the ADC circuit we examined earlier by adding a DAC at the output of the ADC to convert the digital output back to
original analog form.
STEP 4: Double-click on the Oscilloscope instrument ‘XSC1’ to open its front panel then run the simulation. While the simulatio
running, press ‘A’ or ‘Shift-A’ on your keyboard to toggle the input signal.
You will see the following results on the Oscilloscope:
STEP 5: Pause the simulation. Click on “View>>Grapher”. You will notice the output of the DAC we saw on the oscilloscope:
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Thus we have converted the digital signal back to its original analog form and confirmed the theory for both the ADC and the DA
7. NI Suggested Solution
National Instruments offers a number of products that combine to provide a scalable and powerful teaching platform for educato
The solution includes:
NI Multisim circuit teaching environment: Combining an intuitive circuit definition environment, with powerful SPICE simulation
technology, educators can use NI Multisim to easily teach the ins-and-outs of circuits in a safe environment.
NI ELVIS teaching and measurement platform allows educators to provide students with a compact, all-in-one unit for their
measurement and analysis needs. Combining an oscilloscope, function generator, DMM, bode analyzer and 8 other instrument
into a small platform; it simplifies the laboratory experience for students and lab instructors.
8. References
[1] Bartelt, Terry, Wisconsin Technical College System. Analog and Digital Converters.
[http://www.wisc-online.com/objects/ViewObject.aspx?ID=CIS5908]. (15/03/2013)
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