D/A conversion

by Abhiram Ravikumar
PESIT, BSC
 
Every time I think of LD! 

So, what can we do?

Lets make it 

FUn ! :-) :-)

[ yes, that's possible! ]

Happy times ahead . . .

D/a converter


Wanna see something cool?

Go down!

Down arrow

A sneak-peak with Dr. Collin 

Let's get started!

Binary 

equivalent 

weight



     ?? 

truth table for 

3-bit binary signal


Points to remember! 

  • Sum of binary weights should be equal to one. (1)



  • General formula for binary weights associated with LSB:

     


 

Time for a question? 

  Q. What's the binary equivalent   weight                                                of  each bit in a 4-bit system?

Hint: 


Answer: 1/15 , 2/15, 4/15 and 8/15

Resistive Dividers










What should it produce? Exactly this:    

How does it work?

Nothing unusual, the resistors come into play!

  1. Convert LSB(s) to their analog value. ( 001 = 1, 010 =2)
  2. Sum up these analog values.
    simple enough, right? ;-) 

Milliman's theorem

"The voltage between the ends of the circuit is equal to the total current entering the supernode divided by the total equivalent conductance of the supernode". 

Apply the formula for the circuit above. 

Binary Ladders

???






Resistive network!

 Watch This!


A 3-bit DAC in action. :-)

Lets continue with ladder networks...







ladder output voltages


Now, we bring in the 

OP-AMPs


Any idea why?

Obvious, isn't it!

 






 to  
 

by now,


Relax with recap!

  1. Binary weights

  2. Resistive dividers

  3. Binary ladders


AND, WE'RE DONE!


But before that,


What's the basic difference between analog and digital signals?

Relax! You don't have to answer this one.


Resources

1. Find the slides here.
2. Search for more here.
3. Great help from our text by Donald P Leach and co.  


A presentation made by Abhiram Ravikumar.
(just in case you forgot! ;-) )



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