Find output current of NMOS transistor

In summary, the conversation discussed two NMOS transistors, NMOS1 and NMOS2, with different drain, gate, and source voltages. NMOS1 was in the saturation region with a drain voltage of 2.5V and a gate voltage of 1.9V. NMOS2 was in the triode/linear/ohmic region with a drain voltage of 0.5V and a gate voltage of 2.2V. The values for tox, un, and W/L were also given, and the equations for calculating Id for both regions were provided. The attempted solution included calculating the oxide capacitance (cox) and the transistor's transconductance (kn) for both NMOS1
  • #1
ddta1050
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Homework Statement


Vtn = 0.4V
W/L = 10
NMOS1
Saturation Region
Drain = 2.5V
Gate = 1.9V
Source = 0V

Vtn = 0.4V
W/L = 10
NMOS2
Triode/Linear/Ohmic Region
Drain = 0.5V
Gate = 2.2V
Source = -2.3V

tox = 9um
un = 250cm^2/V
W/L = 10

Homework Equations


Saturation: Id = Kn * (Vgs-Vt)^2/2
Triode/Linear/Ohmic: Id = Kn * ((Vgs-Vt)Vds - Vds^2/2)

The Attempt at a Solution


tox = 9nm
un = 250cm^2/V
cox = eox/tox = (3.9*8.85*10^-14F/cm)/9nm = 0.003835F/m^2
kn = un*cox*W/L = 95.875uA/V^2

NMOS1
Ids = Kn * (Vgs-Vt)^2/2 = 1.08mA

NMOS2
Vds = Vd - Vs = 0.5-(-2.3)=2.8V
Ids = Kn * (Vgs-Vt)(Vds) - Vds^2/2) = 7.248mA
 
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  • #2
These look OK to me.
 

1. How do I calculate the output current of an NMOS transistor?

The output current of an NMOS transistor can be calculated using the formula IDS=k(VGS-VT)2, where IDS is the drain-source current, k is the transconductance parameter, VGS is the gate-source voltage, and VT is the threshold voltage.

2. What is the difference between the output current of an NMOS transistor and the drain current?

The output current of an NMOS transistor refers to the current that flows from the drain to the source, while the drain current refers to the current that flows through the drain terminal. The output current takes into account the voltage drop across the channel, while the drain current does not.

3. Can the output current of an NMOS transistor be negative?

Yes, the output current of an NMOS transistor can be negative when the gate-source voltage is below the threshold voltage. In this case, the transistor is in the cutoff region and no current flows through the drain.

4. How does the output current of an NMOS transistor change with increasing gate-source voltage?

The output current of an NMOS transistor increases with increasing gate-source voltage, until it reaches the saturation region. In the saturation region, the output current remains constant regardless of the gate-source voltage.

5. Is there a relationship between the output current and the drain-source voltage of an NMOS transistor?

Yes, the output current is directly proportional to the drain-source voltage in the saturation region. This relationship is described by the equation IDS=k(VGS-VT)2, where k is the transconductance parameter and VT is the threshold voltage.

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