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You Are On Multi Choice Question Bank SET 1028

51401. In the Wien bridge oscillator, which of the following is (are) frequency-determining components?

51402. Determine the input impedance with feedback for a voltage-series feedback having A = –100, R1 = 15 k, Ro = 20 k, and a feedback of = –0.25.

51403. A certain oscillator has a tap on the inductor in the tank circuit. This oscillator is probably

51404. At parallel resonance, the impedance of a crystal is

51405. Refer to this figure. Assuming it is configured as an oscillator and if you desired to reduce the duty to less than 50%, the following circuit change would need to be made.

51406. Calculate the fr of a lead-lag network if R1 = R2 = 6.8 k, and C1 = C2 = 0.05 F.

51407. Which of the following is (are) feedback?

51408. What is the relationship between the series and parallel resonant frequencies of a quartz crystal?

51409. An op-amp integrator has a square-wave input. The output should be

51410. The frequency distortion arising because of varying amplifier gain with frequency is considerably reduced in a negative-voltage feedback amplifier circuit.

51411. An amplifier is stable if the absolute magnitude of A is ________.

51412. ________ is a frequency-determining component in a unijunction oscillator.

51413. In the Colpitts oscillator, the elements X1 and X2 are ________ and X3 is a(n) ________.

51414. In a Hartley oscillator, the elements X1 and X2 are ________ and X3 is a(n) ________.

51415. A feedback amplifier has a ________ upper 3-dB frequency and a ________ lower 3-dB frequency compared to an amplifier without feedback.

51416. What is the gain at the origin of the Nyquist plot?

51417. Positive feedback results in ________.

51418. In the Wien bridge oscillator with R1 = R2 = R and C1 = C2 = C, a ratio of R3 to R4 will provide sufficient loop gain for the circuit to oscillate.

51419. In the phase-shift oscillator, the operating frequency is determined by ________.

51420. In the Barkhausen criterion, the loop gain A is equal to ________.

51421. Negative feedback results in ________.

51422. With feedback, , the overall gain of the circuit is reduced by a factor ________ where A is the gain without the feedback.

51423. Series-feedback connections tend to ________ the input resistance. Shunt feedback connections tend to ________ the input resistance.

51424. In practice, A is made ________ and the system is started oscillating by amplifying noise voltage, which is always present.

51425. Voltage feedback connections tend to ________ the output impedance. Current feedback connections tend to ________ the output impedance.

51426. In the phase-shift oscillator, the gain of the amplifier stage must be ________.

51427. The series-resonant impedance of a crystal oscillator is ________.

51428. An amplifier with negative feedback has ________ bandwidth than (as) the amplifier without feedback.

51429. The parallel-resonant impedance of a crystal oscillator is ________.

51430. In a Nyquist plot, as the frequency increases, the phase shift between input and output signals ________.

51431. At the series-resonant frequency, the amount of positive feedback is ________.

51432. Since the crystal losses represented by R are small, the equivalent crystal Q (quality factor) is ________.

51433. In the Colpitts oscillator, the frequency is determined by ________ .

51434. Typically, a unijunction transistor has a stand-off ratio from ________ to ________.

51435. Crystal oscillators are used whenever a(n) ________ level of stability is required.

51436. The feedback network in a Colpitts oscillator contains two series capacitors and a parallel inductor.

51437. The positive feedback voltage in an oscillator has no net phase shift.

51438. Crystal oscillators are inherently unstable.

51439. For a Wien-bridge oscillator, resonance occurs when Vout/Vin = 1.

51440. LC feedback elements are normally used in oscillators for frequencies greater than 1 MHz.

51441. The frequency in a VCO can be varied with a DC voltage.

51442. Oscillators operate on negative feedback.

51443. The start-up gain of an oscillator must be greater than 1.

51444. The feedback signal in a Hartley oscillator is derived from an inductive voltage in the tank circuit.

51445. In the astable mode, a 555 timer is connected as a free-running relaxation oscillator.

51446. Calculate the value of C1 = C2 for the Wien bridge oscillator to operate at a frequency of 20 kHz. Assume R1 = R2 = 50 k and R3 = 3R4 = 600?

51447. Only the condition A = ________ must be satisfied for self-sustained oscillations to result.

51448. At what phase shift is the magnitude of A at its maximum in the Nyquist plot?

51449. Find the odd one :?

51450. Which Indian become the President of International Court of Justice?

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