MOSFET IV

To study transfer characteristics of MOSFET
Apparatus required: Multisim software
Theory:
MOSFET characteristic:
The MOSFET is actually a four-terminal device, whose substrate, or body terminal must be always held at one of the extreme voltages in the circuit, either the highest positive for the PMOS or the highest negative for the NMOS. One unique property of the MOSFET is that the gate draws no measurable current.
Methodology:

1. Make the circuit with two voltage sources VGS and VDS and BJT in the middle, put voltage to measure output voltage section.
2. For fixed value of VGS, vary the voltage VDS and note the corresponding current ID in table.
3. Now we vary VGS and note the corresponding current.

4. Note the behaviour at VGS = 0V, VGS = VP and VDS = VP points.
5. Now, fix VDS > VP, note values of ID, for 0≤VGS ≤VP in table.
6. Draw Transfer characteristics graph for (VGS vs ID).

Observations:
VGS (Volts)|VDS = 5 V (fixed) IDS (micro A)
0.0 0.0
0.25 0.0
0.5 2.5
0.75 5.62
1.0 10
2.0 40
3.0 90
4.0 160
5.0 250

VDS IDS (µA) VGS = 0.0V IDS (µA) VGS = 1.0V IDS (µA) VGS = 2.0V IDS (µA) VGS = 3.0V IDS (µA) VGS = 4.0V IDS (µA) VGS = 5.0V
0.0 0 0 0 0 0 0
0.25 0 0 0 0 0 0
0.5 0 2.5 2.5 2.5 2.5 2.5
0.75 0 5.62 5.62 5.62 5.62 5.62
1.0 0 10 10 10 10 10
2.0 0 30 40 40 40 40
3.0 0 50 80 90 90 90
4.0 0 70 120 150 160 160
5.0 0 90 160 210 240 250

Conclusion:
For MOSFET we see the transfer characteristics in graph that is when VGS = 0V current will increase till VGS = VT (Threshold Voltage) after this point current ID remains constant. When we fix as VDS > VT and for 0 ≤ VGS ≤ VT current ID will increase as shown in transfer characteristics graph.