Topic Outline
- MCQs in Basic Ideas
- MCQs in Drain Curves
- MCQs in Transconductance Curve
- MCQs in Biasing in the Ohmic Region
- MCQs in biasing in the Active Region
- MCQs in Transconductance
- MCQs in JFET Amplifiers
- MCQs in JFET Analog Switching
- MCQs in Other JFET Applications
- MCQs in JFET Testing
Start Practice Exam Test Questions
Choose the letter of the best answer in each questions.
1. A JFET
- a. Is a voltage-controlled device
- b. Is a current-controlled device
- c. Has a low input resistance
- d. Has a very large voltage gain
2. A unipolar transistor uses
- a. Both free electrons and holes
- b. Only free electrons
- c. Only holes
- d. Either one or the other, but not both
3. The input impedance of a JFET
- a. Approaches zero
- b. Approaches one
- c. Approaches infinity
- d. Is impossible to predict
4. The gate controls
- a. The width of the channel
- b. The drain current
- c. The proportional pinch-off voltage
- d. All the above
5. The gate-source diode of a JFET should be
- a. Forward-biased
- b. Reverse-biased
- c. Either forward- or reverse biased
- d. None of the above
6. Compared to a bipolar transistor, the JFET has a much higher
- a. Voltage gain
- b. Input resistance
- c. Supply voltage
- d. Current
7. The pinch-off voltage has the same magnitude as the
- a. Gate voltage
- b. Drain-source voltage
- c. Gate-source voltage
- d. Gate-source cutoff voltage
8. When the drain saturation current is less than IDSS, a JFET acts like a
- a. Bipolar transistor
- b. Current source
- c. Resistor
- d. Battery
9. RDS equals pinch-off voltage divided by the
- a. Drain current
- b. Gate current
- c. Ideal drain current
- d. Drain current for zero gate voltage
10. The transconductance curve is
- a. Linear
- b. Similar to the graph of a resistor
- c. Nonlinear
- d. Like a single drain curve
11. The transconductance increases when the drain current approaches
- a. 0
- b. ID(sat)
- c. IDSS
- d. IS
12. A CS amplifier has a voltage gain of
- a. gmrd
- b. gmrs
- c. gmrs/(l + gmrs)
- d. gmrd/(l + gmrd)
13. A source follower has a voltage gain of
- a. gmrd
- b. gmrs
- c. gmrs/(l + gmrs)
- d. gmrd/(l + gmrd)
14. When the input signal is large, a source follower has
- a. A voltage gain of less than one
- b. A small distortion
- c. A high input resistance
- d. All of these
15. The input signal used with a JFET analog switch should be
- a. Small
- b. Large
- c. A square wave
- d. Chopped
16. A cascode amplifier has the advantage of
- a. Large voltage gain
- b. Low input capacitance
- c. Low input impedance
- d. Higher gm
17. VHF stands for frequencies from
- a. 300 kHz to 3 MHz
- b. 3 to 30 MHz
- c. 30 to 300 MHz
- d. 300 MHz to 3 GHz
18. When a JFET is cut off, the depletion layers are
- a. Far apart
- b. Close together
- c. Touching
- d. Conducting
19. When the gate voltage becomes more negative in an N channel JFET, the channel between the depletion layers
- a. Shrinks
- b. Expand
- c. Conduct
- d. Stop conducting
20. If a JFET has IDSS = 10 mA and VP = 2 V, then RDS equals
- a. 200 ohm
- b. 400 ohm
- c. 1 kohm
- d. 5 kohm
21. The easiest way to bias a JFET in the ohmic region is with
- a. Voltage-divider bias
- b. Self-bias
- c. Gate bias
- d. Source bias
22. Self-bias produces
- a. Positive feedback
- b. Negative feedback
- c. Forward feedback
- d. Reverse feedback
23. To get a negative gate-source voltage in a self-biased JFET circuit, you must have a
- a. Voltage divider
- b. Source resistor
- c. Ground
- d. Negative gate supply voltage
24. Transconductance is measured in
- a. Ohms
- b. Amperes
- c. Volts
- d. Mhos or Siemens
25. Transconductance indicates how effectively the input voltage controls the
- a. Voltage gain
- b. Input resistance
- c. Supply voltage
- d. Output current
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