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  • Question

  • The amplifier circuit shown below uses a silicon transistor. The capacitors Cc and CE can be assumed to be short at signal frequency and the effect of output resistance r0 can be ignored. If CE is disconnected from the circuit, which one of the following statements is TRUE?
    The amplifier circuit shown below uses a silicon transistor. The capacitors Cc and CE can be assumed


  • Options
  • A. The input resistance Ri increases and the magnitude of voltage gain Av decreases
  • B. The input resistance Ri decreases and the magnitude of voltage gain Av decreases
  • C. Both input resistance Ri and the magnitude of voltage gain Av decrease
  • D. Both input resistance Ri and the magnitude of voltage gain Av increase

  • Correct Answer
  • The input resistance Ri increases and the magnitude of voltage gain Av decreases 

    Explanation
    Given circuit after removing CE will behave as current-series feedback.

    Overall voltage gain will decrease as feedback signal comes into picture and since it is current-series feedback, input impedance increases.

    Exam Questions Papers problems

    Search Results

    • 1. In the following non planar graph number of independent loop equations are

    • Options
    • A. 8
    • B. 12
    • C. 7
    • D. 5
      • Discuss
    • 2. Consider the signal flow graph shown in figure below. The gain is :

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 3. The antenna current of an AM transmitter is 8 A, when only the carrier is sent, but it increases to 8.93 A when the carrier is modulated by a single sine wave. Determine the antenna current when the percent of modulation changes to 0.8

    • Options
    • A. 9.19 A
    • B. 9.91 A
    • C. 10.56 A
    • D. 8.61 A
      • Discuss
    • 4. The gradient of any scalar field always yields __________ .

    • Options
    • A. a solenoidal field
    • B. a conservative field
    • C. an irrotational field
    • D. none of these
      • Discuss
    • 5. Find 'X' in the circuit below :

      f1(A, B, C, D) = ?(6, 7, 13, 14);
      f2(A, B, C, D) = ?(3, 6, 7);
      f3(A, B, C, D) = ?(5, 6, 7, 14, 15)

    • Options
    • A. p(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15)
    • B. 0
    • C. ?(14)
    • D. 1
      • Discuss
    • 6. Consider the amplitude modulated (AM) signal Ac cos ?ct + 2 cos ?mt cos ?ct For demodulating the signal using envelope detector, the minimum value of Ac should be

    • Options
    • A. 2
    • B. 1
    • C. 0.5
    • D. 0
      • Discuss
    • 7. A unity-feedback control system has the open loop transfer function . If the input system is a unit ramp, the steady state error will be

    • Options
    • A. 0
    • B. 0.5
    • C. 2
    • D. infinity
      • Discuss
    • 8. A certain 8 bit uniform quantization PCM system can accommodate a signal ranging from - 1 V to + V. The rms value of the signal is V . The signal to quantization noise ratio is:

    • Options
    • A. 30 dB
    • B. 46.91 dB
    • C. 40 dB
    • D. 49.92 dB
      • Discuss
    • 9. In a semiconductor material. The hole concentration is found to be 2 x 2.5 x 1015 cm-3. If mobility of carriers is 0.13 m2/ v-s. Then find the current density if electric field intensity is 3.62 x 10-19

    • Options
    • A. 7.6237 x 10-4 A/cm2
    • B. 7.6237 x 10-5 A/cm2
    • C. 7.6237 x 10-3 A/cm2
    • D. none of these
      • Discuss
    • 10. The analog signal given below is sampled at 1200 samples per second. m(t) = 2 sin 120 pt + 3 sin 240 pt + 4 sin 360 pt + 5 sin 480 pt + 6 sin 600 pt + 7 sin 720 pt. The folding (maximum) frequency is __________ .

    • Options
    • A. 300 Hz
    • B. 360 Hz
    • C. 600 Hz
    • D. 480 Hz
      • Discuss

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