[SOLVED] what is "weak inversion region"?

[superleaf]

what is "weak inversion region"?is that equal to subthreshold region?is that meant vgs<vth?i'm confused~~~plz help!

 

[analogbeginer]

Yes it is subthreshold region.

 

[varunkant2k]

what is "weak inversion region"?

Yes it is subthreshold region, infact when the gate voltage is sufficient to just reverse the polarity below gate ( in the bulk).

 

[jeet_asic]

why Subthreshold leakage increases if we decrease threshold voltage?

 

[samiurrehman]

weak inversion region and subthreshold region are the same regions. If you look at the cross section of the layout of a simple mosfet(nmos and pmos) you can see a virtual BJT b/w NMOS and PMOS thru which a current flows: leakage current. When your MOS is off(Vg<Vt) this BJT is still conducting current. When MOS is used as an amplifier (mostly pre amplifiers are biased in subthreshold) in this region we say it is operating in weak inversion region. Then we also have strong inversion and moderate inversion and remember these regions have nothing to do with the cutoff,triode and saturation region of a MOS. Just remember when the MOS is off, you can still bias it with that leakage current and make it act like an amplifier. That region is called weak inversion or subthreshold region.

 

[superleaf]

:smile:Thanks a lot for your answer,through your explanation,it is easy to understand~~~

weak inversion region and subthreshold region are the same regions. If you look at the cross section of the layout of a simple mosfet(nmos and pmos) you can see a virtual BJT b/w NMOS and PMOS thru which a current flows: leakage current. When your MOS is off(Vg<Vt) this BJT is still conducting current. When MOS is used as an amplifier (mostly pre amplifiers are biased in subthreshold) in this region we say it is operating in weak inversion region. Then we also have strong inversion and moderate inversion and remember these regions have nothing to do with the cutoff,triode and saturation region of a MOS. Just remember when the MOS is off, you can still bias it with that leakage current and make it act like an amplifier. That region is called weak inversion or subthreshold region.