dac design

how to select Resistor value for R-2R ladder dac.
my op amp is having 13k ohms output resistance.

Would you please let me know about the values of feeback resistor and reference voltage?

Do you have a schematic? Usually the resistors are set such that it divide the reference voltage by a bit count. Example say you have 5 bits, the reference voltage is divides by the following:

1) Vref/1
2) Vref/2
3) Vref/4
4) Vref/8
5) Vref/16

So that when you select you go from full voltage down to 1/16 full voltage if of course it's say 5 bits. So if you do a quick check on your divide string, what does it give you?

Oops, misread your reply...sorry.

That seems rather high for a output impedance -- or do you mean that you have a 13k resistor on the output -- what? As a load or as a feedback resistance or ???

sir, here out put impedence means op amp with out put buffer output impedence.no extra 13k resistor is there

Why not go and buy a college book that covers this subject and look at how a design example is done 1st. Then submit a schematic. You ask a design question and you submit no schematic? Why?

sir, i studied books namely :data converters by franco maloberti,roy choudary, pipelined adc design by imran ahmed.but i didnot get these details i.e., how to select resistor values .please suggest a reference for these design examples. schematic r-2r ladder dac only.

sir, those values i have to find out. please suggest an idea to get those values

Here is what the switches do. Ground all and the input goes to zero, unground all and connect to Vref, and Vout should approach 2x Vref. So as to what you want Vref to be that depends, if you want the output to represent the original sampled voltage, then Vref would be Vmax (sampled)/2.

Say you sampled some voltage and the max sampled voltage was 5V, the Vref would be 5V/2. Therefore when you set all the switched to Vref, the output would approach 5V (never actually reached 5V because of resolution).

Have you actually written out a table that shows what the output voltage is as a function of the switch settings? I hope so. I don't know where this particular algorithm came from but that doesn't matter, it has a purpose.

Have you sorted out any of this, I mean how it works as designed? If so is that how you want it to work?

What is the part number of this op-amp?

Hi

Lots of information here explaining DAC design with schematic examples etc including spdif

see upload below