E7B Amplifiers: class of operation; vacuum tube and solid-state circuits; distortion and intermodulation; spurious and parasitic suppression; switching-type amplifiers
- E7B01 (A)
For what portion of the signal cycle does each active element in a push-pull, Class AB amplifier conduct?
- A. More than 180 degrees but less than 360 degrees
- B. Exactly 180 degrees
- C. The entire cycle
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- E7B02 (A)
What is a Class D amplifier?
- A. An amplifier that uses switching technology to achieve high efficiency
- B. A low power amplifier that uses a differential amplifier for improved linearity
- C. An amplifier that uses drift-mode FETs for high efficiency
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| D. An amplifier biased to be relatively free from distortion |
- E7B03 (A)
What circuit is required at the output of an RF switching amplifier?
- A. A filter to remove harmonic content
- B. A high-pass filter to compensate for low gain at low frequencies
- C. A matched load resistor to prevent damage by switching transients
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| D. A temperature compensating load resistor to improve linearity |
- E7B04 (A)
What is the operating point of a Class A common emitter amplifier?
- A. Approximately halfway between saturation and cutoff
- B. Approximately halfway between the emitter voltage and the base voltage
- C. At a point where the bias resistor equals the load resistor
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| D. At a point where the load line intersects the zero bias current curve |
- E7B05 (C)
What can be done to prevent unwanted oscillations in an RF power amplifier?
- A. Tune the stage for minimum loading
- B. Tune both the input and output for maximum power
- C. Install parasitic suppressors and/or neutralize the stage
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| D. Use a phase inverter in the output filter |
- E7B06 (B)
What is a characteristic of a grounded-grid amplifier?
- A. High power gain
- B. Low input impedance
- C. High electrostatic damage protection
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- E7B07 (D)
Which of the following is the likely result of using a Class C amplifier to amplify a single-sideband phone signal?
- A. Reduced intermodulation products
- B. Increased overall intelligibility
- C. Reduced third-order intermodulation
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| D. Signal distortion and excessive bandwidth |
- E7B08 (B)
Why are switching amplifiers more efficient than linear amplifiers?
- A. Switching amplifiers operate at higher voltages
- B. The switching device is at saturation or cutoff most of the time
- C. Linear amplifiers have high gain resulting in higher harmonic content
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| D. Switching amplifiers use push-pull circuits |
- E7B09 (D)
What is characteristic of an emitter follower (or common collector) amplifier?
- A. Low input impedance and phase inversion from input to output
- B. Differential inputs and single output
- C. Acts as an OR circuit if one input is grounded
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| D. Input and output signals in-phase |
- E7B10 (B)
In Figure E7-1, what is the purpose of R1 and R2?
- A. Load resistors
- B. Voltage divider bias
- C. Self bias
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- E7B11 (D)
In Figure E7-1, what is the purpose of R3?
- A. Fixed bias
- B. Emitter bypass
- C. Output load resistor
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- E7B12 (C)
What type of amplifier circuit is shown in Figure E7-1?
- A. Common base
- B. Common collector
- C. Common emitter
- D. Emitter follower
