Download JFET Single Stage Amplifier Phys 3610/6610 Lab 21 Student: TA:

Phys 3610/6610 Lab 21
Student:
TA:
JFET Single Stage Amplifier
Task 1: Use the 2N5485 n-channel JFET as in fig.1 to make a simple amplifier. The circuit should
use VDD = +12 V, VSS = −12 V, VD = (6 ± 1) V, and ID = (1.0 ± 0.2) mA. Design the biasing
needed for these parameters, calculate the circuit gain for your circuit design, and compare with
the measured value. Use your breadboard’s 5 V, 1 kHz source to make a 25 mV, 1 kHz source
from it as input to your circuit.
VDD
R
Vout
Vin
your
design
your
design
VSS
Figure 1: Block diagram
Task 2: Evaluate what will happen if a 1 MΩ resistor is inserted between your amplifier input
and your 25 mV, 1 kHz signal source. Document your prediction and then go ahead and verify it
experimentally. Document and interpret your experimental result.
Task 3: Modify the circuit of task 1 to use the VN10KM MOSFET rather than the JFET. Besides
having much greater current capability, this MOSFET is an enhancement mode device (the JFET
is depletion mode). Proceed as in task 1.
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