Question 1

Which of the following is not a requirement for oscillator operation?

Accepted Answer

A)  The circuit must fulfill the Barkhausen criterion. 
B)  The circuit must initially be triggered into operation. 
C)  The feedback network must contain an RC circuit. 
D)  The circuit must provide positive feedback. 
A)  The circuit must fulfill the Barkhausen criterion. 
B)  The circuit must initially be triggered into operation. 
C)  The feedback network must contain an RC circuit. 
D)  The circuit must provide positive feedback. C

Question 2

A Colpitts oscillator has in its feedback network.

Accepted Answer

A)  a pair of tapped capacitors in parallel with an inductor 
B)  a pair of tapped inductors in parallel with a capacitor 
C)  a transformer with a capacitor in parallel with its primary winding 
D)  a pair of tapped capacitors in parallel with an inductor and a third small-value capacitor 
A)  a pair of tapped capacitors in parallel with an inductor 
B)  a pair of tapped inductors in parallel with a capacitor 
C)  a transformer with a capacitor in parallel with its primary winding 
D)  a pair of tapped capacitors in parallel with an inductor and a third small-value capacitor A

Question 3

A Clapp oscillator has in its feedback network.

Accepted Answer

A)  a pair of tapped capacitors in parallel with an inductor 
B)  a pair of tapped inductors in parallel with a capacitor 
C)  a transformer with a capacitor in parallel with its primary winding 
D)  a pair of tapped capacitors in parallel with an inductor and a third small-value capacitor 
A)  a pair of tapped capacitors in parallel with an inductor 
B)  a pair of tapped inductors in parallel with a capacitor 
C)  a transformer with a capacitor in parallel with its primary winding 
D)  a pair of tapped capacitors in parallel with an inductor and a third small-value capacitor D

Question 4

-At fp, a crystal has impedance.

Accepted Answer

A)  low 
B)  high 
A)  low 
B)  high

Question 5

-A big advantage that LC oscillators have over RC oscillators is the fact that LC oscillators can generally be operated at much higher frequencies.

Accepted Answer

A) True 
 B)False

Question 6

Positive feedback is also called

Accepted Answer

A)  degenerative feedback. 
B)  additive feedback. 
C)  regenerative feedback. 
D)  regressive feedback. 
A)  degenerative feedback. 
B)  additive feedback. 
C)  regenerative feedback. 
D)  regressive feedback.

Question 7

The positive feedback circuit in a Wien-bridge oscillator is used to

Accepted Answer

A)  determine the frequency of operation. 
B)  control the gain of the circuit. 
C)  bias the negative feedback network. 
D)  prevent unwanted oscillations. 
A)  determine the frequency of operation. 
B)  control the gain of the circuit. 
C)  bias the negative feedback network. 
D)  prevent unwanted oscillations.

Question 8

The Barkhausen criterion states that the product of voltage gain and current gain in an oscillator must equal one 1).

Accepted Answer

A) True 
 B)False

Question 9

Phase-shift oscillators are rarely used because

Accepted Answer

A)  they are very difficult to produce. 
B)  their output amplitudes are very hard to regulate. 
C)  their output frequencies tend to be extremely unstable. 
D)  they require the use of an op-amp. 
A)  they are very difficult to produce. 
B)  their output amplitudes are very hard to regulate. 
C)  their output frequencies tend to be extremely unstable. 
D)  they require the use of an op-amp.

Question 10

The Wien-bridge oscillator is limited to output frequencies that are around 1 MHz or less.

Accepted Answer

A) True 
 B)False

Question 11

The negative feedback circuit in a Wien-bridge oscillator is used to

Accepted Answer

A)  determine the frequency of operation. 
B)  control the gain of the circuit. 
C)  bias the positive feedback network. 
D)  prevent unwanted oscillations. 
A)  determine the frequency of operation. 
B)  control the gain of the circuit. 
C)  bias the positive feedback network. 
D)  prevent unwanted oscillations.

Question 12

CCOs have

Accepted Answer

A)  very low operating frequencies. 
B)  very stable output frequencies. 
C)  extremely simple biasing circuits. 
D)  All of the above. 
A)  very low operating frequencies. 
B)  very stable output frequencies. 
C)  extremely simple biasing circuits. 
D)  All of the above.

Question 13

Which of the following is considered the least expensive when manufacturing crystal oscillators?

Accepted Answer

A)  Lead crystal 
B)  Rochell salt 
C)  Quartz 
D)  Tourmaline 
A)  Lead crystal 
B)  Rochell salt 
C)  Quartz 
D)  Tourmaline

Question 14

-The circuit in Figure has the following values: RFC = 100 μH, C1 = 1 μF, and C2 = 33 μF. What is the value of Av for the circuit?

Accepted Answer

A)  0.03 
B)  33 
C)  0.01 
D)  100 
A)  0.03 
B)  33 
C)  0.01 
D)  100

Question 15

In a positive feedback system, the feedback signal and the amplifier input signal are

Accepted Answer

A)  in phase. 
B)  45° out of phase. 
C)  90° out of phase. 
D)  180° out of phase. 
A)  in phase. 
B)  45° out of phase. 
C)  90° out of phase. 
D)  180° out of phase.

Question 16

-At fs, a crystal has impedance.

Accepted Answer

A)  high 
B)  low 
A)  high 
B)  low

Question 17

Which of the following is not used as crystals in oscillator circuits?

Accepted Answer

A)  Lead crystal 
B)  Rochell salt 
C)  Quartz 
D)  Tourmaline 
A)  Lead crystal 
B)  Rochell salt 
C)  Quartz 
D)  Tourmaline

Question 18

A three-stage BJT amplifier is found to be producing unwanted oscillations. Which of the following will solve the problem?

Accepted Answer

A)  Reducing the overall voltage gain of the amplifier 
B)  Using a regulated dc power supply 
C)  Increasing the supply voltage for the amplifier 
D)  Replacing the BJTs with JFETs 
A)  Reducing the overall voltage gain of the amplifier 
B)  Using a regulated dc power supply 
C)  Increasing the supply voltage for the amplifier 
D)  Replacing the BJTs with JFETs

Question 19

In a practical phase-shift oscillator, each RC circuit produces a 60° phase shift.

Accepted Answer

A) True 
 B)False

Question 20

An oscillator is a circuit that

Accepted Answer

A)  converts ac to dc. 
B)  converts dc to ac. 
C)  converts one ac frequency to another frequency. 
D)  performs all of the above conversions. 
A)  converts ac to dc. 
B)  converts dc to ac. 
C)  converts one ac frequency to another frequency. 
D)  performs all of the above conversions.

Exam 18: Oscillators

Which of the following is not a requirement for oscillator operation?

A Colpitts oscillator has in its feedback network.

A Clapp oscillator has in its feedback network.

-At fp, a crystal has impedance.

-A big advantage that LC oscillators have over RC oscillators is the fact that LC oscillators can generally be operated at much higher frequencies.

Positive feedback is also called

The positive feedback circuit in a Wien-bridge oscillator is used to

The Barkhausen criterion states that the product of voltage gain and current gain in an oscillator must equal one 1).

Phase-shift oscillators are rarely used because

The Wien-bridge oscillator is limited to output frequencies that are around 1 MHz or less.

The negative feedback circuit in a Wien-bridge oscillator is used to

CCOs have

Which of the following is considered the least expensive when manufacturing crystal oscillators?

-The circuit in Figure has the following values: RFC = 100 μH, C1 = 1 μF, and C2 = 33 μF. What is the value of Av for the circuit?

In a positive feedback system, the feedback signal and the amplifier input signal are

-At fs, a crystal has impedance.

Which of the following is not used as crystals in oscillator circuits?

A three-stage BJT amplifier is found to be producing unwanted oscillations. Which of the following will solve the problem?

In a practical phase-shift oscillator, each RC circuit produces a 60° phase shift.

An oscillator is a circuit that

Fundamental Solid-State Principles

Diodes

Common Diode Applications: Basic Power Supply Circuits

Common Diode Applications: Clippers, Clampers, Voltage Multipliers, and Displays

Special Applications Diodes

Bipolar Junction Transistors

DC Biasing Circuits

Introduction to Amplifiers

Common-Emitter Amplifiers

Other BJT Amplifiers

Power Amplifiers

Field-Effect Transistors

Mosfets

Amplifier Frequency Response

Operational Amplifiers

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Tuned Amplifiers

Solid-State Switching Circuits

Thyristors and Optoelectronics Devices

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