Delta Sigma DAC

[DaveLdn]

Hi,
I've been asked to compare the delta sigma ADC and DAC circuits as part of a college assignement. I've done the ADC section as I'm happy that I understand what's going on, but I can't get my head around the DAC version.
Can anyone give me a quick walkthrough of what's happening at each stage?
I've attached the flowchart diagram that I have but I don't understand what the MSBIT does or why the circuit feeds back to the adder from the latch output.



Thanks
Dave

 

[Harald Kapp]

Hello Dave,
find an explanation here: http://en.wikipedia.org/wiki/Delta-sigma_modulation#Digital_to_analog_conversion

Basically the analog signal is approximated by a very fast stream of '0's and '1's such that the averaged value (low pass filtered) is the analog signal. Therefore the schematic attached to your post is in my view incomplete without this averaging or low pass filter.

Harald

 

[DaveLdn]

Hi Harald,
Thanks for the quick reply. That has helped me.
Dave