Re: NOISE in MOSFET?
Flicker noise seems due to random trapping/detrapping of carriers near the Si/SiO2 interface. But the subject is still under active discussion.
Thermal noise origin is the same as for resistor: random movement of cariers due to thermal excitation.
As to suppress them:
- Flicker noise can be reduced in low frequency circuits (like audio) by using double sampling or chopping. See the excellent article by Enz and Temes 'Circuit techniques for reducing the effects of op-amp imperfections: autozeroing, correlated double sampling, and chopper stabilization'
- For thermal noise, you need to reduce it by circuit design consideration (as said by gunturikishore you need to increase the SNR)
Hopes it helps
regards