April 2020 StudentZone Quiz Solution

Question 1:

By plotting the NMOS/PMOS data measured for ID vs VGS, find and report values of VTH and K (W/L). How do the VTH and K (W/L) values for the NMOS and PMOS compare?

Answer 1:

NMOS:

Consider Scopy plot obtained the in the lab activity:

The threshold voltage can be obtained by observing the data on the plot, where the transistor starts conducting (turns on). In our case the measured threshold voltage is around VTH=1.8V.

The VGS value is obtained by taking the largest voltage value on the x-axis. In this case, VGS=2.4V

In the saturation region, the current flowing through the transistor can be measured by dividing the maximum voltage obtained on the Y axis by the resistor value used in the setup (100Ω).

IDSAT = 4.8V/100Ω = 48mA

K(W/L) is obtained using the formula for drain current in the saturation region.

IDSAT = K(W/L) * (VGS-VTH)2

K(W/L) = 0.13

PMOS:

Follow the same steps as for the NMOS, but using the appropriate Scopy plot

We obtain: VTH=2.9V, VGS=4.1V, IDSAT=3.8V/100Ω=38mA

 

K(W/L) = 0.026