# Gibilisco - Amplifiers And Oscillators

19 Questions | Total Attempts: 350  Settings  • 1.
The decibel is a unit of
• A.

Relative signal strength.

• B.

Voltage.

• C.

Power.

• D.

Current.

• 2.
An oscillator at RF requires the use of
• A.

A common drain or common collector circuit.

• B.

A stage with gain.

• C.

A tapped coil.

• D.

A quartz crystal.

• 3.
Suppose a circuit is found to have a gain figure of −15 dB. Which of the following statementsis true?
• A.

The output signal is stronger than the input signal.

• B.

The input signal is stronger than the output signal.

• C.

The input signal is 15 times as strong as the output signal.

• D.

The output signal is 15 times as strong as the input signal.

• 4.
In an oscillator circuit, the feedback should be
• A.

As great as possible.

• B.

Kept to a minimum.

• C.

Just enough to sustain oscillation.

• D.

Done through a transformer whose wires can be switched easily.

• 5.
A power gain of 44 dB is equivalent to which of the following output/input power ratios?
• A.

44:1

• B.

160:1

• C.

440:1

• D.

25,000:1

• 6.
An RF choke
• A.

Passes RF signals but blocks dc.

• B.

Passes both RF signals and dc.

• C.

Passes dc but blocks RF signals.

• D.

Blocks both dc and RF signals.

• 7.
The optimum capacitance values in an amplifier circuit depend on
• A.

The power-supply voltage.

• B.

The power-supply polarity.

• C.

The input signal strength.

• D.

The input signal frequency.

• 8.
An oscillator might fail to start for any of the following reasons, except
• A.

Low battery voltage.

• B.

Low stage gain.

• C.

In-phase feedback.

• D.

• 9.
In which of the following FET amplifier types does drain current flow for exactly 50 percentof the signal cycle?
• A.

Class A

• B.

Class AB1

• C.

Class AB2

• D.

Class B

• 10.
The frequency at which a quartz crystal oscillator produces energy is largely dependent on
• A.

• B.

The physical thickness of the quartz wafer.

• C.

The amount of resistance through the crystal.

• D.

The power-supply voltage.

• 11.
Which bipolar amplifier type has some distortion in the signal wave, with collector currentduring most, but not all, of the cycle?
• A.

Class A

• B.

Class AB1

• C.

Class AB2

• D.

Class B

• 12.
An RF oscillator usually
• A.

Produces an output signal with an irregular waveshape.

• B.

Has most or all of its energy at a single frequency.

• C.

Produces a sound that depends on its waveform.

• D.

Employs an RC circuit to determine the output amplitude.

• 13.
A class C amplifier can be made linear by
• A.

Reducing the bias.

• B.

Increasing the drive.

• C.

Using two transistors in push-pull.

• D.

No means; a class C amplifier is always nonlinear.

• 14.
A frequency synthesizer has
• A.

High power output.

• B.

High frequency drift rate.

• C.

Exceptional stability.

• D.

• 15.
A graphic equalizer is a form of
• A.

Bias control for an NPN bipolar transistor.

• B.

Gain control for an RF oscillator.

• C.

Tone control that can be used in an audio amplifier.

• D.

Circuit for adjusting the waveform of an RF oscillator.

• 16.
If the impedance of the load connected to the output of an oscillator is extremely high,
• A.

The frequency will drift excessively.

• B.

The power output will be reduced.

• C.

The oscillator might fail to start.

• D.

It is no cause for concern; in fact, it is a good thing.

• 17.
Suppose a certain bipolar-transistor PA is 66 percent efficient. The output power is 33 W.The dc collector power input is
• A.

22 W.

• B.

50 W.

• C.

2.2 W.

• D.

• 18.
A tuned RF PA must always be
• A.

Set to work over a wide range of frequencies.

• B.

• C.

Operated at an even harmonic of the input frequency.

• D.

Operated in class C.

• 19.
Class B amplification can be used to obtain low distortion for audio applications
• A.

By connecting two amplifiers in cascade, thereby maximizing the gain and generating a pure sine wave output.

• B.

By biasing the bipolar transistor or FET beyond cutoff or pinchoff, thereby ensuring that the output is in phase with the input.

• C.

By connecting two identical bipolar transistors or FETs, biased exactly at cutoff or pinchoff, in a push-pull configuration.

• D.

By biasing the bipolar transistor or FET in the middle of the straight-line portion of the characteristic curve. Back to top