Lab 6 – JFET Characteristics
and SelfBiasing
Reading: 
Bogart, Beasley, & Rico, Electronic Devices and
Circuits, Sections 52 and 53. 


Objectives: 
After completing this experiment, you will be able to: ·
Measure and graph the drain and transfer characteristics
for a JFET. ·
Measure V_{GS(off)} and I_{DSS}
for a JFET. ·
Investigate the JFET selfbias configuration
and calculate dc quiescent voltages and currents for the JEFT selfbias
configuration. 


Procedure: 
1. Use
the circuit in Figure 1 to take data and plot the drain characteristic plot (V_{DS} vs I_{D}) and transfer characteristic (plot V_{GS} vs I_{D}) for the 2N5486 JFET. Measure
I_{D} for values of V_{DS} of 0V, 0.5V, 1V, 5V, 10V,
and 15V and for values of V_{GS}
from 0 to 6 volts in steps of 1 V. Plot
I_{D} on the horizontal
axis for both graphs, and label each axis with suitable units and calibration
points. 2. Determine
V_{GS(off)} and I_{DSS} from the characteristic
curves of the JFET. 3. For
the circuit of Figure 2, calculate the operating point values for V_{GS}
and I_{D}. 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 V_{GS}, I_{D}, and V_{DS}. 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. 


Questions: 
1. Explain how to find I_{DSS} from
the characteristic curves of a JFET. 


Figure 1: 



Figure 2: 



Figure 3: 
