Electronic Devices and Circuits Multiple Choice Questions on “Small Signal Operations and Model”.
1. A transistor with ß = 120 is biased to operate at a dc collector current of 1.2 mA. Find the value of gm.
A. 12mA/V
B. 24 mA/V
C. 36 mA/V
D. 48 mA/V
2. A transistor with ß = 120 is biased to operate at a dc collector current of 1.2 mA. Find the value of R?p.
A. 625 ohm
B. 1250 ohm
C. 2500 ohm
D. 5000 ohm
3. A transistor with ß = 120 is biased to operate at a dc collector current of 1.2 mA. Find the value of Re.
A. 2.5 ohm
B. 20.6 ohm
C. 25.2 ohm
D. 30.4 ohm
4. A transistor operating with nominal gm of 60 mA/V has a ß that ranges from 50 to 200. Also, the bias circuit, being less than ideal, allows a 20% variation in Ic. What is the smallest value found of the resistance looking into the base?
A. 347 ohm
B. 694 ohm
C. 1041 ohm
D. 1388 ohm
5. A transistor operating with nominal gm of 60 mA/V has a ß that ranges from 50 to 200. Also, the bias circuit, being less than ideal, allows a 20% variation in Ic. What is the largest value found of the resistance looking into the base?
A. 1050 ohm
B. 21000 ohm
C. 3150 ohm
D. 4200 ohm
6. A designer wishes to create a BJT amplifier with a gm of 50 mA/V and a base input resistance of 2000 O or more. What is the minimum ß he can tolerate for the transistor used?
A. 100
B. 150
C. 200
D. 250
7. A designer wishes to create a BJT amplifier with a gm of 50 mA/V and a base input resistance of 2000 O or more. What emitter bis current should he choose?
A. 1.06 mA
B. 1.16 mA
C. 1.26 mA
D. 1.36 mA
8. Which of the following is true?
A. Ib = ß Ic
B. Ib = ß + 1/ Ic
C. Ib = Ic/ß
D. Ib = Ic/ ß – 1
Answer: C
Clarification: The correct relationship between Ic and Ie is Ib = Ic/ß.
9. The SI units of transconductance is
A. Ampere/ volt
B. Volt/ ampere
C. Ohm
D. Siemens
Answer: A
Clarification: Transcoductance is given by Ic/Vt.
10. Which of the following represents the correct mathematical form of the term denoted by the symbol Rp?
A. ß/gm
B. Vt/Ib
C. All of the mentioned
D. None of the mentioned
Answer: C
Clarification: Both of the expressions are identical.