What is Sigma-Delta Modulation?

Can anyone explain what is Sigma-Delta Modulation in DAC or ADC?

Thanks and Best Rgards!

Apollo

I attached a good book of S D convertters.



Delta modulation is a Data Communication Technique for transmit Analog Data whit discrete voltage levels (digital).

It samples the signal at a high rate (more than twice its bandwidth) and calculate the diference between the current sample and the last sample. If the difference is positive, you transmit a positive pulse, and if the difference is negative you transmit a negative one. The interesting thing is that you just send one "bit" per sample.

This technique is a special case of Differential PCM (that encodes those sample differences with mor than one bit).

This method has limitations (you can transmit analog data with a given slew rate)

Sigma delta is a modification of that way of transmitting data. It kills Delta Modulation limitations. Also, it has better characteristics facing noise issues.

This system can be seen as a diferentiator a Delta modulator and a integrtor in serie. That change introduces those benefits. This technique is a good way of samplig analog data for implement ADCs (with a post downsamplig)

Simple introduction:
https://www.beis.de/Elektronik/DeltaSigma/DeltaSigma.html

Sigma is add,can be implemented with integrator. Delta is subtract, can be implemented with negative feedback.

In sigma delta, the main Idea is adding an integrator to the beginning of the delta modulator to decrease the slope overloading effect.

Added after 1 minutes:

By the way, the best thing about it is the simplicity at the receiver. In fact, the receiver is simply a low pass filter.