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Op-amp design to use in 8 bit R-2R ladder DAC

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circuitking

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Hi, I need to design a 8-bit DAC. I also need to design the Op-amp that is used in DAC. I studied in Analog Integrated Circuits Design (Johns,Martin) book that the op-amp could drive either resistor or capacitor load. If the load is resistor, buffer stage should be included in the discrete op-amp design. So i am thinking, Since the op-amp in R-2R DAC has the resistors in the feedback i need include buffer stage in the design.

I want to confirm whether my understanding is correct. Kindly provide any information on how to design an opamp that includes buffer stage in its design.Thanks
 

Hi,

A R-2R DAC may be built without Opamp, but it has relatively high ohmic output.
And relative low ohmic reference input.

You should be aware, that
* we don't see the circuit you are talking about
* we don't know your requirement / specification
* we don't even know if you are talking about IC design..

Thus the anser can just be general:

If you want high ohmic reference input --> use an Opamp.
If you want low ohmic output --> use an Opamp.

It's always a good idea to post a simple drawing....

Klaus
 

I have a hunch the exercise is to build an R-2R network, then add an op amp to serve as a buffer. This is the conventional arrangement which you'll find in schematics on the internet after a Google search.

To design an entire op amp is a big task which requires experience with differential amplifiers, current mirrors, and half-bridges.
 

Hi,

A R-2R DAC may be built without Opamp

Is there any book to refer about this?

- - - Updated - - -

I have a hunch the exercise is to build an R-2R network, then add an op amp to serve as a buffer.
So in that case, can we just replace an op-amp with a buffer such as CC/CD stage?
 

An older Analog Devices databook, '80s vintage, will
be worth more than a semester's lectures if you apply
yourself. You will find the DACs and in their application
notes, op amps that work best.

archive.org has lots of databooks scanned to PDF (and
other formats).
 

Hi,

Is there any book to refer about this?
What about an internet search " R 2R DAC schematic" ?

Klaus
 

Depending to configuration of your DAC, the opamp can has different spec.
Provide more detail.
 

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