Question 1

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 capacitorE) A) and D)
F) B) and D) D

Question 2

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 JFETsE) None of the above
F) B) and D)

Question 3

-At fp, a crystal has impedance.

Accepted Answer

A)   low
B)   highC) A) and B)
D) undefined

Question 4

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.E) A) and C)
F) B) and C)

Question 5

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.E) C) and D)
F) A) and B)

Question 6

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.E) None of the above
F) A) and D)

Question 7

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

Accepted Answer

A) True 
 B)False

Question 8

CCOs have

Accepted Answer

A)   very low operating frequencies.
B)   very stable output frequencies.
C)   extremely simple biasing circuits.
D)   All of the above.E) None of the above
F) A) and D)

Question 9

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 10

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 capacitorE) A) and B)
F) A) and C) A

Question 11

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.E) All of the above
F) B) and C) C

Question 12

-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)   100E) C) and D)
F) None of the above

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

Positive feedback is also called

Accepted Answer

A)   degenerative feedback.
B)   additive feedback.
C)   regenerative feedback.
D)   regressive feedback.E) A) and B)
F) A) and C)

Question 15

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

Accepted Answer

A)   Lead crystal
B)   Rochell salt
C)   Quartz
D)   TourmalineE) A) and C)
F) C) and D)

Question 16

-At fs, a crystal has impedance.

Accepted Answer

A)   high
B)   lowC) A) and B)
D) undefined

Question 17

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.E) A) and B)
F) B) and D)

Question 18

-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 19

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

Accepted Answer

A)   Lead crystal
B)   Rochell salt
C)   Quartz
D)   TourmalineE) A) and B)
F) A) and C)

Question 20

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.E) B) and C)
F) A) and B)

Exam 18: Oscillators

A Clapp oscillator has in its feedback network.

Correct AnswerverifiedD

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

Correct AnswerverifiedShow Answer

-At fp, a crystal has impedance.

Correct AnswerverifiedShow Answer

An oscillator is a circuit that

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Phase-shift oscillators are rarely used because

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

CCOs have

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

A Colpitts oscillator has in its feedback network.

Correct AnswerverifiedA

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

Correct AnswerverifiedC

-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?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Positive feedback is also called

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

-At fs, a crystal has impedance.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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