# Microwave Oscillators MCQ’s

This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “Microwave Oscillators”.

1. Any device with negative impedance as its characteristic property can be called:
a) Energy source
b) Energy sink
c) Oscillator
d) None of the mentioned

2. In a microwave oscillator, a load of 50+50j is connected across a negative resistance device of impedance -50-50j. Steady state oscillation is not achieved in the oscillator.
a) True
b) False

3. In microwave oscillators, negative resistance transistors and diodes are used in order to generate oscillations in the circuit.
a) True
b) False

4. For achieving steady state oscillation, the condition to be satisfied in terms of reflection coefficients is:
a) ГinL
b) Гin=-ГL
c) Гin=1/ГL
d) None of the mentioned

5. If the input impedance of a diode used in the microwave oscillator is 45-j23 Ω, then the load impedance is to achieve stable oscillation is:
a) 45-j23 Ω
b) -45+j23 Ω
c) 50 Ω
d) 23-j45 Ω

6. In transistor oscillators, the requirement of a negative resistance device is satisfied using a varactor diode.
a) True
b) False

7. A one port oscillator uses a negative resistance diode having Гin=0.9575+j0.8034 (Z0=50Ω) at its desired frequency point. Then the input impedance of the diode is:
a) -44+j123
b) 50+j100
c) -44+j145
d) None of the mentioned

8. To achieve stable oscillation, Zin + ZL=0 is the only necessary and sufficient condition to be satisfied by the microwave oscillator.
a) True
b) False

9. In transistor oscillators, FET and BJT are used. Instability is achieved by:
a) Giving a negative feedback
b) Giving a positive feedback
c) Using a tank circuit
d) None of the mentioned

10. In a transistor amplifier, if the input impedance is -84-j1.9 Ω, then the terminating impedance required to create enough instability is:
a) -84-j1.9 Ω
b) 28+j1.9 Ω
c) – (28+j1.9) Ω
d) None of the mentioned