Electronic Devices and Circuits EET2222


Lab 6 JFET Characteristics and Self-Biasing




Bogart, Beasley, & Rico, Electronic Devices and Circuits, Sections 5-2 and 5-3.





After completing this experiment, you will be able to:

        Measure and graph the drain and transfer characteristics for a JFET.

        Measure VGS(off) and IDSS for a JFET.

        Investigate the JFET self-bias configuration and calculate dc quiescent voltages and currents for the JEFT self-bias configuration.






1.      Use the circuit in Figure 1 to take data and plot the drain characteristic plot (VDS vs ID) and transfer characteristic (plot VGS vs ID) for the 2N5486 JFET. Measure ID for values of VDS of 0V, 0.5V, 1V, 5V, 10V, and 15V and for values of VGS from 0 to 6 volts in steps of 1 V. Plot ID on the horizontal axis for both graphs, and label each axis with suitable units and calibration points.


2.      Determine VGS(off) and IDSS from the characteristic curves of the JFET.


3.      For the circuit of Figure 2, calculate the operating point values for VGS and ID. Use the graphical method on your plot of the transfer characteristic.


4.      Set up the circuit of Figure 2 and measure the operating point values for VGS, ID, and VDS.


5.      Calculate and draw the load line for the circuit of Figure 2 on your plot of the output characteristics (include all calculations). Indicate the measured operating point of your circuit with a dot on your plot.


The report for this lab is due at the end of the lab period. Please use the green engineering paper.





1. Explain how to find IDSS from the characteristic curves of a JFET.




Figure 1:





Figure 2:





Figure 3: