Aim:-
1. To measure drain current ๐ผ๐ , at different values of gate voltage .
2. To measure drain current ๐ผ๐ , for different values of drain โ source voltage . To plot input /output characteristics curves and evaluate the parameters.
Apparatus:- ย
JFET (BFW10), Bread board, Regulated Power supply (0 – 2 V) and (0 – 12 V), Ammeters (0 – 20 mA), Voltmeter V1 (0 – 2V), Voltmeter V2, (0 – 10V), Connecting wires (Single Strand).
Theory:-
A Junction Field-Effect Transistor (JFET) is a three-terminal semiconductor device used for amplification or switching electronic signals. Its operation is based on the control of current flow between two of its terminals (the source and the drain) by a voltage applied to the third terminal (the gate).
The drain current (ID) of the JFET is controlled by the application of reverse- biased voltage between gate and source terminals (VGS). The relationship between ID and VGS is defined by the well-known Shockleyโs equation.
Circuit Diagram:-
Procedure:-
Drain characteristics :-
- Connect the circuit as shown in the figure1.
- Keep VGS = 0V by varying VGG.
- Varying VDD gradually in steps of 1V up to 10V note down drain current ID and drain to source voltage (VDS).
- Repeat above procedure for VGS = -0.4, -0.8, -1.2 and -1.6 V.
- Plot the drain characteristics by taking VDS on X-axis and ID on Y-axis at a constant VGS.
Transfer characteristics:-
- Connect the circuit as shown in the figure1.
- . Set voltage VDS = 4V/8V
- Varying VDS in steps of 0.5V until the current ID reduces to minimum value.
- Varying VGG gradually, note down both drain current ID and gate- source voltage (VGS).
- Repeat above procedure (step 3) for VDS = 4V/ 8V.
- Plot the transfer characteristics by taking VGS on X-axis and taking ID on Y-axis at constant VDS.
Observations :-
| Drain characteristics | |||||||||
| s.no. | Vds | Vgs = | Vgs= | Vgs = | Vgs = | ||||
| Vds | Id | Vds | Id | Vds | Id | Vds | Id | ||
| 1 | |||||||||
| 2 | |||||||||
| 3 | |||||||||
| 4 | |||||||||
| 5 | |||||||||
| 6 | |||||||||
| Transfer characteristics | ||||
| s.no. | Vds = | Vds = | ||
| Vgs | Id | Vgs | Id | |
Precaution :-
- Avoid double connection if possible .
- The connection should be proper and tight
Result :- ย
Drain and Transfer characteristics of a FET are studied.
