Recently, i read some articles about oversampling AD/DA,but in some articles sigma-delta structure is mentioned and in others delta-sigma structure is introductioned. And i am confused about this.Some people tells me that they are the same, someone else tells me that in AD sigma-delta structre is used, delta-sigma is adopted by DA!
I think there is no difference. I submitted a conference paper to IEEE about sigma delta ADC. There are some typing errors making sigma-delta and delta-sigma both presenting, but no comments on this issue at all
They are all the same. Although Delta-Sigma may be "better" in that it reveals the the principle as hanjiemy mentioned, Sigma-Delta is widely accepted now.
They are not the same originally, you can see its difference in ‘Delta-sigma data converters --- theory,design, and simulation' IEEE press.
Now they are the same meaning, a modulator technique.
1. Delta-Sigma Modulator
Here the first order integrator is in the feedback path. The difference between the actual signal
and the integrator output is compared and quantized.
2. Sigma-Delta Modulator
Here the first order integrator is in the feedforward path after the substraction from the
quantized signal. The output of the integrator feed the quantizer.
Although one may try to find out different meanings of both terms, it's completely obvious that in scientific literature they effectively designate the same object. Apparently most authors prefer either one or another and usually take care for consistent terminology within their publications.
Fixing the difference has a strong scholastic smell and is rather unlikely to give theoretical insights, to my opinion.