# Voltage Controlled Oscillator MCQ’s

This set of Linear Integrated Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Voltage Controlled Oscillator”.

1. If the output of the Schmitt trigger is given below. Estimate the output at the pin 3 of VCO.

a) b) c) d) 2. Write the equation for time period of VCO?
a) (2×Vcc×CT)/i
b) (Vcc CT)/(2×i)
c) (Vcc×CT×i)/2
d) (2×Vcc)/(i×CT)

3. Which device is used for diagnostic purposes and for recording?
a) Low pass filter
b) Monolithic PLL
c) Voltage Controlled Oscillator
d) None of the mentioned

4. Determine the value of current flow in VCO, when the NE566 VCO external timing resistor RT =250Ω and the modulating input voltage Vc=3.25V.(Assume Vcc=+5v).
a) 3mA
b) 12mA
c) 7mA
d) 10mA

5. The output frequency of the VCO can be changed by changing
a) External tuning resistor
b) External tuning capacitor
c) Modulating input voltage
d) All of the mentioned

6. What is the advantage of using filter?
a) High noise immunity
b) Reduce the bandwidth of PLL
c) Provides dynamic range of frequencies
d) None of the mentioned

7. From the circuit given, find the value of output frequency?

a) 178.484 Hz
b) 104.84 Hz
c) 145.84 Hz
d) 110.88 Hz

8. Calculate the value of external timing capacitor, if no modulating input signal is applied to VCO. Consider fo=25 kHz and RT=5 kΩ.
a) 6nF
b) 100µF
c) 2nF
d) 10nF

9. Which filter is used in VCO?
a) b) c) d) All of the mentioned

10. Voltage to frequency conversion factor for VCO is
a) Kv = △Vc/ △fo
b) Kv = △fo/△Vc
c) Kv = △fo × △Vc
d) Kv = 1/(△fo×△Vc)

11. Find the equation for change in frequency of VCO?
a) △fo = (2×△Vc)/(RT×CT×Vcc)
b) △fo = △Vc/(4×RT×CT×Vcc)
c) △fo = △Vc/(2×RT×CT×Vcc)
d) △fo = (4×△Vc)/(RT×CT×Vcc)

12. Choose the VCO for attaining higher output frequency.
a) NE566
b) SE566
c) MC4024
d) All of the mentioned

13. Calculate the voltage to frequency conversion factor, where fo=155Hz and Vcc=10V.
a) 130
b) 124
c) 134
d) 116

14. Using the given specifications, determine the voltage to frequency conversion factor.

a) 8.32
b) 8.90
c) 8.51
d) 8.75 5 Star
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