Practice Pakistan's most useful MCQs for competitive exams

An ideal OP-AMP is an ideal___________?

• (A)  Current controlled Current source
• (B)  Current controlled voltage source
• (C)  Voltage controlled voltage source
• (D)  voltage controlled current source

Answer

Submitted By :Ali Uppal

An amplifier without feedback has a voltage gain of 50,input resistance os 1 KΩ & Output resistance of 2.5KΩ.The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 is___________?

• (A)  1/11KΩ
• (B)  1/5KΩ
• (C)  5KΩ
• (D)  11KΩ

Answer

Submitted By :Ali Uppal

In the differential voltage gain & the common mode voltage gain of a differential amplifier are 48db &2db respectively, then its common mode rejection ratio is__________?

• (A)  23dB
• (B)  25dB
• (C)  46dB
• (D)  50dB

Answer

Submitted By :Ali Uppal

Generally, the gain of a transistor amplifier falls at high frequencies due to the___________?

• (A)  Internal Capacitance of the device
• (B)  Coupling capacitor at the input
• (C)  Skin effect
• (D)  Coupling capacitor at the output

Answer

Submitted By :Ali Uppal

The current gain of a bipolar transistor drops at high frequencies because of____________?

• (A)  Transistor capacitances
• (B)  High current effects in the base
• (C)  Parasitic inductive elements
• (D)  The early effect

Answer

Submitted By :Ali Uppal

Negative feedback in an amplifier____________?

• (A)  Reduces gain
• (B)  Increase frequency &phase distortion
• (C)  Reduces bandwidth
• (D)  Increases noise

Answer

Submitted By :Ali Uppal

Class AB operation is often used in power large signal amplifiers in order to_________?

• (A)  get maximum efficiency
• (B)  remove even harmonics
• (C)  overcome a crossover distortion
• (D)  reducing collector dissipation

Answer

Submitted By :Ali Uppal

An n- channel JFET has IDSS=2mA,and Vp=-4v.Its transconductance gm=in mA/V)for an applied gate to source voltage VGS=-2v is___________?

• (A)  0.25
• (B)  0.5
• (C)  0.75
• (D)  1

Answer

Submitted By :Ali Uppal

The effective channel length of a MOSFET in a saturation decreases with increase in___________?

• (A)  Gate voltage
• (B)  Drain voltage
• (C)  Source voltage
• (D)  Body voltage

Answer

Submitted By :Ali Uppal

A differential amplifier is invariably used in the i/p stage of all OP-amps. This is done basically to provide the OP-amps with a very high_________?

• (A)  CMMR
• (B)  Bandwidth
• (C)  Slew rate
• (D)  Open-loop gain

Answer

Submitted By :Ali Uppal