1. At series resonance, the impedance of a crystal is

**A. minimum.**- B. maximum.
- C. equal.
- D. zero.

2. What is the total phase shift requirement, around the feedback loop, for a phase-shift oscillator?

- A. 90°
- B. 180°
- C. 270°
**D. 360°**

3. In order to start up, a feedback oscillator requires

- A. negative feedback less than 1.
**B. positive feedback greater than 1.**- C. unity feedback equal to 1.
- D. no feedback.

4. What is the relationship between the series and parallel resonant frequencies of a quartz crystal?

- A. They are equal.
**B. Parallel resonant frequency is approximately 1 kHz higher than series resonant frequency.**- C. Series resonant frequency is approximately 1 kHz higher than parallel resonant frequency.
- D. none of the above

5. At parallel resonance, the impedance of a crystal is

- A. minimum.
**B. maximum.**- C. equal.
- D. zero.

6. What is the minimum frequency at which a crystal will oscillate?

- A. seventh harmonic
- B. third harmonic
**C. fundamental**- D. second harmonic

7. Calculate the fr of a lead-lag network if R1 = R2 = 6.8 kΩ, and C1 = C2 = 0.05 µF.

**A. 468 Hz**- B. 4.68 kHz
- C. 46.8 kHz
- D. 468 kHz

8. A certain oscillator has a tap on the inductor in the tank circuit. This oscillator is probably

- A. a Colpitts oscillator.
- B. a Clapp oscillator.
- C. a crystal oscillator.
**D. a Hartley oscillator.**

9. A circuit that can change the frequency of oscillation with an application of a dc voltage is sometimes called

**A. a voltage-controlled oscillator.**- B. a crystal oscillator.
- C. a Hartley oscillator.
- D. an astable multivibrator.

10. Sinusoidal oscillators operate with _____ feedback.

**A. positive**- B. negative

11. One condition for positive feedback is that the phase shift around the feedback loop must be _____°.

**A. 0**- B. 90
- C. 180
- D. 45

12. An op-amp integrator has a square-wave input. The output should be

- A. a sine wave.
**B. a triangle wave.**- C. a square wave.
- D. pure dc.

13. The start-up gain of an oscillator must be _____ one.

- A. equal to
- B. less than
**C. greater than**- D. none of the above

14. For frequencies up to 1 MHz, the _____ is the most widely used type of sinusoidal RC oscillator.

**A. Wien-bridge**- B. phase-shift
- C. twin-T
- D. none of the above

15. The lead-lag circuit in the Wien-bridge oscillator has a resonant frequency at which the attenuation is

- A. 1/2.
- B. 1/4.
**C. 1/3.**- D. 1/5.

16. The attenuation of the three-section RC feedback phase-shift oscillator is

- A. 1/9.
- B. 1/30.
- C. 1/3.
**D. 1/29.**

17. The feedback signal in a(n) _____ oscillator is derived from an inductive voltage divider in the LC circuit.

**A. Hartley**- B. Armstrong
- C. Colpitts
- D. none of the above

18. The feedback signal in a(n) _____ oscillator is derived from a capacitive voltage divider in the LC circuit.

- A. Hartley
- B. Armstrong
**C. Colpitts**- D. none of the above

19. The twin-T oscillator produces a _____ response.

- A. low-pass
- B. high-pass
- C. band-pass
**D. band-stop**