Hi, The easiest thing in my opinion is just to remember the following: "Negative Body Biasing raises VT". For an NMOS, that means that if I put a negative voltage on the bulk, my VT is higher. For a PMOS, the opposite - if the NWELL is biased higher than VDD, the |VT| of the PMOS becomes higher (i.e., the VT becomes more negative). To understand in general, physicists have many ways of explaining things that are all different ways of looking at them. One thing you could try is that there is a certain amount of voltage you need to apply to the gate in order to invert the channel. If I put a negative voltage on the body, I need to apply more voltage on the gate to bring the channel to the same voltage. This can be supported by the two capacitor drawing I show many times in the slides, where the gate-to-channel capacitor is what we want to control the channel, but the channel-to-body (or channel-to-others) capacitance is "fighting" with the gate voltage. If we apply a negative body voltage (on an NMOS), we are effectively increasing the gate-to-body cap and making it harder to invert the channel. Hope that helps...
i am seeing one at a time and..getting confident. Well done.
Great!
Thank you very much sir.... Superb explanation.. Great presentation...
If possible please upload videos for compact modeling using Spice
I am actually planning on giving a lecture on SPICE this semester, so keep posted!
Thank you sir
You're welcome :)
very nice course !
Thank you! Cheers!
Your videos useful brother
Thank you so much 🙂
Can anyone help me understanding Body Effect intuitively without using equations?
Hi,
The easiest thing in my opinion is just to remember the following: "Negative Body Biasing raises VT". For an NMOS, that means that if I put a negative voltage on the bulk, my VT is higher. For a PMOS, the opposite - if the NWELL is biased higher than VDD, the |VT| of the PMOS becomes higher (i.e., the VT becomes more negative).
To understand in general, physicists have many ways of explaining things that are all different ways of looking at them. One thing you could try is that there is a certain amount of voltage you need to apply to the gate in order to invert the channel. If I put a negative voltage on the body, I need to apply more voltage on the gate to bring the channel to the same voltage. This can be supported by the two capacitor drawing I show many times in the slides, where the gate-to-channel capacitor is what we want to control the channel, but the channel-to-body (or channel-to-others) capacitance is "fighting" with the gate voltage. If we apply a negative body voltage (on an NMOS), we are effectively increasing the gate-to-body cap and making it harder to invert the channel.
Hope that helps...