Course title :Electronics ll

Electrical Engineering Department (NDll)

Course code:EEC 214

Solved past question .
QUESTION ONE
Define faithful application.
State the principle of operation of JFET transistors.
Of what advantage is the high input impedance of JFET.
Compare in a tabular for the terminals of FET and BJT.
Use the figure below to answer question f and g.
What is the role of the emitter by pass capacitor CE
Select a suitable value for the emitter by pass capacitor for the circuit above if the amplifier is to operate over a frequency range from 2KHz to 10K
QUESTION TWO
a) Define the following terms and parameter for JFET.
I) AC drain resistance, r
ii) Irans conductance, g
iii) Amplification factor,

(b) State the relationship between the terms in (a) above.
(C) when a reverse gate voltage of 15V is applied to a JFET, the gate current is 10-3. Find the resistance between gate and source.
QUESTION THREE
a) Sketch the output characteristics of a FET transistor indicating the following,
(I) short-gate drain current.
(ii) Pinch off voltage.
(b) Write the expression for the drain current in FET.
(c) A JFET has the following parameters IDSS=32mA, VGS(OFF) =-8V, VGS=-4.5 find the value of the drain current, ID.
QUESTION FOUR
(a) State three (3) application of JFET.
(b) State two (2) reasons for transistor biasing.
(c) In a transistor amplifier, when the signal changes by 0.02V the base current change by 10 and collector current by 1mA. If collector load Rc=5K and RD=10K find;
Current gain
Input resistance.