All Questions
19
questions
0
votes
1
answer
32
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Diffusion Current for Non-Linear Charge Carrier Configurations
Diffusion current in a MOSFET device can be calculated using Fick's Law per \$J=-qD\frac{d \rho}{dx}\$. It is often taken that the charge carrier configuration (\$\rho\$) across the MOSFET channel is ...
- 1
1
vote
0
answers
200
views
Effect of semiconductor doping on threshold voltage
After reading online, I have modeled this as an relation between the threshold voltage and the doping concentration:
For a N-channel MOSFET on a P-type substrate:
$$
V_{T,N} \propto \sqrt{N_{A}}
$$
...
- 31
4
votes
3
answers
659
views
Potential distribution in MOSFET
Let us assume that an NMOSFET has its source, drain and substrate grounded therefore VDS and VSB=0 V . We apply a gate voltage VGS=2 V and I want to know how this potential is distributed as we move ...
- 49
2
votes
0
answers
192
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MOSFET gate substrate voltage
In a MOSFET the channel is formed between gate and the body it would sense to use gate body voltage to form the channel. Why is gate source voltage used to form the channel?
0
votes
1
answer
300
views
Is an NMOS device symmetrical with regard to its D and S pins? [duplicate]
Can D and S be swapped? (Assuming the body is not internally connected to S.)
The structure of a MOSFET is totally symmetric. Even the LTspice simulation shows that it can be swapped.
Does this ...
- 440
6
votes
4
answers
949
views
In a JFET, is the gate *always* connected to the bulk/substrate?
In a JFET, is the gate always connected to the bulk/substrate ?
Or is there "no rule" (sometimes it is, sometimes it is not)?
And what about the case of the MOSFET ?
1
vote
1
answer
3k
views
Why does channel length modulation only occur in the saturation region?
As drain voltage is increased, the reverse bias across the drain-body junction also increases and thus the width of the junction should also increase which should deplete the channel length as well. ...
- 469
0
votes
3
answers
2k
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Gate leakage current for a JFET?
I'm really confused about how JFETs work. JFETS are usually significantly higher doped donor xor acceptor atoms.
My professor mentioned that MOSFETs usually have an oxide in between the the metal and ...
0
votes
1
answer
202
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the transconductance of cascade MOSFET IF channel length modulation is NOT ZERO
What would the derivation of the cascode MOSFET transconductance in small signal analysis IF THE CHANNEL LENGTH MODULATION IS NOT ZERO, as most examples for the cascode mosfet transconductance say in ...
3
votes
5
answers
3k
views
Why reverse connected MOSFET start to turn on at Vgs<Vth?
The circuit shown below is implemented using two AO3400 N-MOSFETs.
AO4300 datasheet here.
The right-hand MOSFET is connected with normal polarity (Vds is positive),
while the left-hand MOSFET is ...
- 93
6
votes
1
answer
163
views
MOSFET switching on
I have a doubt. Consider an N-MOSFET: which is the voltage that can switch on it? The voltage between Gate and? Sometimes I read "between Gate and Bulk", sometimes "between Gate and Source", sometimes ...
- 3,550
1
vote
2
answers
285
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Cause of triode mode in MOSFET
My reference text introduces the MOFSET as follows:
The text says the induced channel has uniform width as long as \$v_{DS}\$ is small, because in that case \$v_{GD} = v_{GS} - v_{DS} \approx v_{GS}\$...
- 137
2
votes
0
answers
116
views
How does a MOSFET conduct in saturation region?
It is a simple question but I could not find a straightforward answer.
When a MOSFET enters saturation region, the channel length starts to decrease, and the channel width is the smallest near the ...
0
votes
3
answers
164
views
Is it possible to create a (depletion mode) MOSFET using only single type of semiconductor?
If I understood JFET diagram correctly, the p-n junction is only used to isolate gate. Using same principle, would it be possible to construct a MOSFET with no junction at all, i. e. a single ...
- 13
3
votes
1
answer
2k
views
Why does the MOSFET drain current increase abruptly when Gate voltage is greater than the threshold voltage?
As far I've understood, channel formation takes place because of the induced negative charge on the semiconductor side of the gate capacitance. So shouldn't the charge concentration increase linearly ...
- 187