Page 229 - Op Amps Design, Applications, and Troubleshooting

Review Questions 211

REVIEW QUESTIONS

1. In order for a sinewave oscillator to maintain a constant-amplitude (undistorted)
output waveform, the overall closed-loop gain must be .
2. What is the general name for an oscillator circuit whose frequency is determined by
the magnitude of input voltage?
3. Refer to Figure 4.2. This circuit uses (positive, negative) feedback that is (AC, DC)
coupled.
4. Refer to Figure 4.2. Will the circuit oscillate if the 1N914A diode becomes open?
Explain your answer.
5. Refer to Figure 4.3. What is the primary purpose of resistor R 2?
6. Refer to Figure 4.5. If capacitor Q is made larger, what happens to the frequency at the
output of Ail Does the amplitude of the signal at the output of A 2 change?
7. Refer to Figure 4.5. Explain the effect on circuit operation if resistor R 4 is changed to 20
kilohms.
8. Refer to Figure 4.8. If capacitor Q is changed to 0.33 microfarad, RI is set to 100
kilohms, and R 3 is set to 0, compute the following:
a. Positive pulse width
b. Duty cycle
c. Frequency
9. Refer to Figure 4.12. Amplifier A 2 operates as a circuit.
10. Refer to Figure 4.3. Compute the frequency of operation if K t, R 2/ Q/ and C 2 are
changed to the following values:
KT = R 2 = 4.7 kQ
Cj = C 2 = 1500 pF