Body effect and Deep N well

[rennguyen123]

What are body effects? Why can we use deep n well to fix the body effect in mos. Can anyone explain it to me?

 

[dick_freebird]

MOS body effect means that any reverse bias of B wr.t. S adds to the effective VT, a fraction of that voltage (60% roughly). In cheap CMOS flows the NMOS has it's body pinned to substrate. The NMOS is what RF ICs use for the HF amplifier and switch paths, often the "native" (VT ~ 0). Substrate noise can also "communicate" with G by Cgs and the channel capacitance to body, a noise / harmonics/ intermods problem.
But worst, your "VT=0" FET becomes VT=0.6V if you operate at S potential of +1V. Goodbye, "sporty". Hello, common mode nonlinearities.

Wrap a DNW (+TNW) around a NMOS FET and you cut its connection to bulk substrate. Fix those issues at cost of layout area, greatly increased Css (so a better play for common source gain stage, than common drain followers). Gain some authority over noise couplings. Also can give you above-rail operation, like for bootstrapped bridge drivers.

 

[rennguyen123]

MOS body effect means that any reverse bias of B wr.t. S adds to the effective VT, a fraction of that voltage (60% roughly). In cheap CMOS flows the NMOS has it's body pinned to substrate. The NMOS is what RF ICs use for the HF amplifier and switch paths, often the "native" (VT ~ 0). Substrate noise can also "communicate" with G by Cgs and the channel capacitance to body, a noise / harmonics/ intermods problem.
But worst, your "VT=0" FET becomes VT=0.6V if you operate at S potential of +1V. Goodbye, "sporty". Hello, common mode nonlinearities.

Wrap a DNW (+TNW) around a NMOS FET and you cut its connection to bulk substrate. Fix those issues at cost of layout area, greatly increased Css (so a better play for common source gain stage, than common drain followers). Gain some authority over noise couplings. Also can give you above-rail operation, like for bootstrapped bridge drivers.

I still don't quite understand the definition of body effect, can you make it easier to understand. I am newbie. Could you use pictures to make it easier for me to understand? Thank you very much