sigma delta adc in matlab
Continuous-time sigma-delta's are not less sensitive to noise ! BUT as the sampling occurs inside the loop (by the action of the quantizer) there is :
1) no folding of the noise...kt/C noise is the result of the sampling of the noise of a resistor on a capacitor...
2) all the sampling related errors are shaped out-of-band like it is the case for the quantization error in discrete-time sigma-delta
3) no sampling at the input + loop filter reduces the specs of your anti-alias filter
HOWEVER,
1) you are very sensitive to the first amplifier (mainly noise and distortion) of your loop filter which is connected directly to the input signal
2) you are sensitive to the noise of your feedback DAC for the same reasons
3) the actual shape of your DAC output waveform matters
4) jitter on the clock driving the feedback DAC will probably be a major problem
good paper on continuous-time sigma-delta attached