Electronic Devices and Circuit Theory-Oscillator Circuits
Electronic Devices and Circuit Theory-Oscillator Circuits
11. In order to start up, a feedback oscillator requires
- negative feedback less than 1.
- positive feedback greater than 1.
- unity feedback equal to 1.
- no feedback.
12. The amplifier is unstable if the Nyquist curve plotted encloses (encircles) the –1 point, and it is stable otherwise.
- TRUE
- FALSE
13. Which of the following oscillators is (are) tuned oscillators?
- Colpitts
- Hartley
- Crystal
- All of the above
14. The Nyquist plot combines the two Bode plots of gain versus frequency and phase shift versus frequency on a single plot.
- TRUE
- FALSE
16. The lead-lag circuit in the Wien-bridge oscillator has a resonant frequency at which the attenuation is
- 1/2
- 1/4.
- 1/3.
- 1/5.
17. The start-up gain of an oscillator must be ________ one.
- equal to
- less than
- greater than
18. In the IC phase-shift oscillator, what should the ratio of feedback resistor Rf to R1 be?
- Zero
- Greater than –29
- Less than 29
- Any value
20. For frequencies up to 1 MHz, the ________ is the most widely used type of sinusoidal RC oscillator.
- Wien-bridge
- phase-shift
- twin-T
- [NIL]