An npn BJT has gm=38mA/v, cµ =10¯14 F, cπ =10¯13F and DC current gain β0=90.For this transistor fT & fβ are________?

Related Mcqs:

1. The current gain of a BJT is__________?

   A. gm r0
   B. gm / r0
   C. gm rπ
   D. gm /rπ

2. 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

3. 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

4. Which of the following amplifier circuit using junction transistor has the best gain?

   A. Common base
   B. Common emitter
   C. Common collector
   D. All have the same gain

5. A 741-type OP-AMP has a gain-bandwidth product of 1MHz. A non-inverting amplifier using this op-amp & having a voltage gain of 20db will exhibit -3db bandwidth of__________?

   A. 50 KHz
   B. 100KHz
   C. 1000/17 KHz
   D. 1000/7.07 KHz

6. 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

7. Three identical amplifiers with each one having a voltage gain of 50,input resistance of 1KΩ & output resistance of 250 ,are cascaded.The open circuit voltage gain of combined amplifier is_________?

   A. 49dB
   B. 51dB
   C. 98dB
   D. 102dB

8. A differential amplifier has a differential gain of 20,000 . CMRR=80 dB. The common mode gain is given by________?

   A. 2
   B. 1
   C. 1/2
   D. 0

9. In a transistor leakage current mainly depends on__________?

   A. doping of base
   B. size of emitter
   C. rating of transistor
   D. temperature

10. 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