Sigma Delta

This is the output for my fyp, sigma delta modulator. Generally, the noise shaping is working; notice how the low frequency components have lower noise compared to the higher frequency ones. This is because the low frequency noise has been "shifted" to the higher frequency part so that the signal of interest, which is in the lower frequency domain, is not affected by noise.

However, the result is far from expectation. 80dB of SNR is a far cry from the desired 120+dB that is required of a 20-bits sigma delta modulator. Sad. Sibeh sian. =((

And most people reading this dunno what i talking about. Also sibeh sian. No one can help me..