Amplifier Sample Questions

1. The voltage gain of a certain servo amplifier is increased by a factor of 10. How much is the gain increased in decibels?

1. 20 dB
2. 2 dB
3. 10 dB
4. 1 dB
5. 100 dB

2. If the gain of a voltage amplifier is 30 dB and the input signal is 5 volts, what is the output signal voltage?

1. 158 volts
2. 150 volts
3. 5 volts
4. 16 volts
5. 60 volts

3. When deciding between thyristors and transistors as the power devices in a motor amplifier, it is important to remember that

1. thyristors have lower conduction losses than equivalent transistors
2. thyristors have lower switching losses than equivalent transistors
3. thyristors have lower maximum current ratings than equivalent transistors
4. thyristors have lower maximum voltage ratings than equivalent transistors
5. thyristors and equivalent transistors have roughly the same characteristics

4. Which of the following are valid criticisms of using pulse width modulation (PWM) as an amplification technique rather than a linear amplifier?

1. PWM causes more high frequency noise
2. linear amplifiers have lower power dissipation
3. linear amplifiers are better suited to large motors
4. PWM can only be implemented in analog systems
5. PWM causes more low frequency noise

5. A notch filter is most often identified with which of the following?

1. band-reject filter
2. band-pass filter
3. low-pass filter
4. high-pass filter
5. lag filter

Page Revised: July 14, 2003