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37 Threads found on Channel Inversion
I have read BSIM manual for charge partition in channel. However I don't understand one thing; when using 0/100 charge partition scheme while all of inversion charge is accounted by source node, how is capacitance measured (since Cdb = dQd/dVb). Thanks.
That would want some more details on just how far below VTH. In weak inversion, it's still inversion and channel carriers will be source species. In depletion you may still see some state- or trap-hopping / tunneling transport. But I question altogether the validity of saying a FET will be biased by an arbitrary current and an unknown (...)
Electrons in the inversion layer are always provided by source or drain n+ heavily doped regions - irrespective of whether this is bulk device, fully- or partially-depleted SOI - assuming there is n+ region in proximity with the gate. (without n+ regions, electrons are provided through thermal generation in the depletion layer under the gate - but
In today's short-length channel technologies (sub 22 nm), which effect is more important channel length modulation or velocity saturation? and, what is the most important effect of the secondary effects?
Good for decoupling applications where you can count on the DC voltage you need to drive full inversion and low "access resistance" (channel). Poor for applications where you require low variation in C across a wide range of DC bias (or large signal operation). CV swing can give you harmonic distortion issues in RF and analog amplifiers. This is w
A MOSCAP requires a minimum voltage across it to give the maximum capacitance. It gives the maximum capacitance when it is in strong inversion i.e. the Vgs > Vth when the channel is full formed. Check Razavi's "Design of Analog CMOS Integrated Circuits" page 39. Btw, MIMCAPs ca be placed over active devices and therefore might not be as much
In old CMOS processes, where the square law was a good approximation, vdsat should indeed be equal to vgs-vth when the transistor is in strong inversion and channel modulation can be ignored (long L). In your case the transistor is in moderate inversion as vgs is almost equal to vth. Try to make vgs a little higher and then re-check vdsat. (...)
You might expand your searching to include "buried channel MOSFET" which has been around for many decades, and for the reason you're after.
Anything with a depletion region on either side of it will be voltage dependent. MOS channels swing from accumulation through depletion to inversion. Cgs follows gate voltage directly; Cgd, only when the channel is well lit near the drain (linear region - when it goes constant current the capacitance is sort of stood off from the (...)
What a textbook long channel device does, and what a short channel real device does, diverged a few decades back. Lambda for starters, add in DIBL and you're nowhere near Kansas anymore.
Traditionally MOSFET drive current reduced with increasing temperature. Hence for most cases worst case delay corner used to be high temperature (100C or higher, depending on target application). With transistor scaling, VDD and Vt have scaled but not as aggressively as the rest of the parameters (such as gate oxide thickness, channel length etc.).
Hi all, when I was reading Hans Camenzind's book ( ), I have a question at page 33. Here is what the author said --------- If you place all the p-channel transistors in a common n-well, you get the smallest total area and therefore the lowest cost. But if the source of such a t
The device is turned off, there is no channel. so yes you will have a constant cap but the cap is now a Gate to Body cap, which is very small. essentially like having a small strip of poly over nothing(think parasitic cap). for the device to act as a good cap, you need to make use of the very very small gap between the gate and the channel (the ver
Hello, So I've read that the body effect increases VT by virtue of VSB > 0. This pulls more -ive ions into the channel. This increases the amt of gate charge needed to mirror these -ive ions prior to an inversion layer forming. This increase in the amt of gate charge translates to an increase in VT. However, what about the dependance of VT
New methods, other than using longer than minimum channel length, and strong inversion operation mode?
I read in article that "At short channel lengths the halo doping of the source overlaps that of the drain, increasing the average channel doping concentration, and thus increasing the threshold voltage. This increased threshold voltage requires a larger gate voltage for channel inversion. However, as (...)
I read that in an n-mosfet, when drain voltage is increased above threshold (in saturation mode) the inversion channel between the source and drain is pinched-off near the drain region. so the channel length decreases and so its resistance. so larger current flows through the channel. My doubt is, when a smaller portion is (...)
channel length modulation (CLM) strongly depends on channel length itself, on Vds and on inversion operation mode, hence should be extracted at an appropriate operation point. On absence of other conflicting effects which may also affect the gradient of the Id-vs-Vds characteristic (DIBL, hot electron injection), the CLM parameter λ (...)
The channel is what connects gate plate capacitance to the drain (and source). When the channel goes away only the overlap & fringing capacitance is "hooked up", the rest is returned to body instead of the inversion sheet when not inverted.
For high speed / RF, you want many narrow fingers to hold down Rg. For analog you want wider, as much mismatch (esp at weak inversion) can come from the channel edge (bird's beak) or strain effects (STI). Your foundry may or may not break down mismatch into area, w, l dependencies (often only area is discussed; whether this is because the others d