Hi everyone,
After searching on internet and this forum i didn't find what im looking for, so i will make a second question and if anyone can help me i would be glad.

I have the below recuit (image attached).

Goal:
Find Equivalent Resistance when the switch is in position 1 and on position 2.

VDD = 3 V
VT = 0.2 V
K = 0.41 mA/V^2

 

Any attempt from your side?

Also remember that:

Req = VDD/ID

Where:

ID = K*(VGS - VT)^2

 

Any attempt from your side?

Also remember that:

Req = VDD/ID

Where:

ID = K*(VGS - VT)^2

Hello, thanks for the effort.
How can i find VGS?

Do i need to use this types below?
Switcher on position 1:
R1= VDD/ ID

Switcher on position 2:
R2= VDD/ IDSS

 

How can i find VGS?

Simply, just answer yourself a question:
What is the voltage between the gate terminal and the source terminal when the switch is in position 1 and 2?

Switcher on position 1:
R1= VDD/ ID

Yes.

Switcher on position 2:
R2= VDD/ IDSS

Yes.

Also, you should check if you MOSFET is in a triode region or in a saturation region.

 

Simply, just answer yourself a question:
What is the voltage between the gate terminal and the source terminal when the switch is in position 1 and 2?

VGS = 3V ?
How can i find IDSS ?

 

VGS = 3V ?

Yes.

How can i find IDSS ?

If it was not given then you can assume that Idss = 0A.

 

So the solving of this exercise, is the below?

ID = K*(VGS - VT)^2
= 0.41*(3 - 0.2)^2
= 3.21 mA

Switcher on position 1:
R1= VDD/ ID
= 3/ 3.21
= 0.91 kohm

Switcher on position 2:
R2= VDD/ IDSS
= 3 kohm

Do i need anything else?

 

So the solving of this exercise, is the below?

ID = K*(VGS - VT)^2
= 0.41*(3 - 0.2)^2
= 3.21 mA

Switcher on position 1:
R1= VDD/ ID
= 3/ 3.21
= 0.91 kohm

Switcher on position 2:
R2= VDD/ IDSS
= 3 kohm

Do i need anything else?

You need to track your units through each step of your work -- it will save you serious time and grief if you do.

ID = K*(VGS - VT)^2
= (0.41 mA/V²)*(3 V - 0.2 V)^2
= 3.21 mA

Switcher on position 1:
R1= VDD/ ID
= 3 V / 3.21 mA
= 0.91 kΩ

What is Idss? Why don't you put it in your final equation? You are implying that it is 1 mA, where does this value come from? What did Jony130 say about what we generally assume it to be if not provided?

 

You need to track your units through each step of your work -- it will save you serious time and grief if you do.

ID = K*(VGS - VT)^2
= (0.41 mA/V²)*(3 V - 0.2 V)^2
= 3.21 mA

Switcher on position 1:
R1= VDD/ ID
= 3 V / 3.21 mA
= 0.91 kΩ

What is Idss? Why don't you put it in your final equation? You are implying that it is 1 mA, where does this value come from? What did Jony130 say about what we generally assume it to be if not provided?

Hello, thanks for the effort to help me out.

i really dont know what is this IDSS... i found a similar exercise that is using it when the switcher is on Position 2.
(i dont know if it is correct)
Thats why im asking how to find IDSS... and as Jony130 said if it not given assume it is 0(zero).