Homework 4-3
Amplifiers
1. A semiconductor device
operated in the switching mode may be
considered as a(n)
a.
power source
b. load
c. digital device
answer
d. analog device
2. A semiconductor device
being operated in a linear mode may be
considered as a(n)
a.
power source
b. load
c. digital device
d. analog device
answer
3. Define the operation of
an amplifier
A small
control voltage is used to control a much larger voltage being fed into the
device. The net result is a larger version of the input signal being
produced at the output. Amplifiers are used to amplify voltage, current, or
power.
4. The gain of an
amplifier may be measured in
a.
voltage
b.
current
c.
power
5. An amplifier state with
an input of 0.1 volt and an output of 2 volt would
have a gain of
a. 5
b. 10
c. 20
answer
d. 0.2
6. The symbol for
impedance is
a. E
b. I
c. R
d. Z
answer
7. Impedance is measured
in
a. volts
b. ohms
answer
c. amps
d. watts
8. What is the best power
transfer and lowest distortion achieved from an
amplifier stage?
This occurs when the output impedance of the
first stage matches the input impedance of the second stage.
9. Define the term
"distortion"
This is when there are undesired changes in
the waveform of a signal between the input and the output.
10. Name three common
types of distortion
a.
frequency
b.
phase
c.
amplitude
11. Which type of
distortion is commonly due to the inductance and/or
capacitance used in a circuit?
frequency
12. Which type of
distortion is due to a signal being displayed while passing
through
a circuit?
phase
13. Which type of
distortion is due to a signal being clipped at the output of
an
amplifier
amplitude
14. Name three types of
amplitude distortion
a.
harmonic
b.
intermodulation
c.
transient intermodulation
15. Define the purpose of
a voltage amplifier stage.
Voltage amplifiers are commonly used to
amplify the weak signals to a level sufficient to operate a power amplifier
stage.
16. Define the purpose of
a power amplifier stage.
Power amplifiers are commonly used to boost
the incoming signal strength (from the voltage amplifier stages) to a level
sufficient to operate a load like a speaker, relay coil, or any output
device.
17. A well regulated power
supply is essential for the proper operation of
any
amplifier circuit. The power supply must satisfy three basic
requirements. What are they?
a.
supply sufficient energy
b.
set the bias point
c.
set the operating conditions
18. What circuit
determines the operating condition of an amplifier state
a bias circuit
19. Amplifiers are
generally operated between two operating conditions.
What
are they?
20. Define the quiescent
point on an amplifiers' characteristic curve.
This is the operating point which determines
the class of operation that the amplifier will operate in.
21. Where is the "Q" point
located on the characteristic curve of a class A
amplifier?
In the middle of the characteristic curve
22. Where is the "Q" point
located on the characteristic curve of a class B
amplifier?
At the cutoff point on the lower knee of the
amplifier's characteristic curve.
23. Where is
the "Q" point located on the characteristic curve of a class
AB1 amplifier?
A little more negative than is the class A
operating point
24. Where is the "Q" point located on the characteristic
curve of a class
AB B2
amplifier?
At the top of the lower knee of the
amplifier's characteristic curve
25. Where is
the "Q" point located on the characteristic curve of a class C
amplifier?
About two and 1/2 times the cutoff value
26. Which of the amplifier
classes listed below would never be used for
audio reproduction?
a. class A
b. class B
c. class AB1
d. class AB2
e. class C
answer
27. What is the DC load
line on an amplifier's characteristic curve?
This is a line drawn between the cutoff and
saturation point of a typical amplifier family of characteristic curves. The
Q point usually operates along this line.