111. An amplifier has an open loop gain of 100, an input impedance of 1kΩ, and an out put impedance of 100 Ω. If a feedback network with a feedback factor of 0.99 is connected in a voltage series feedback mode then new input and output impedances are
     (a)
     (b)
     (c)

1. 1. 10 Ω and 1 Ω

   
   
   

   2. 10 Ω and 10 k Ω

   
   
   

   3. 100 k Ω and 1 Ω
      

   
   
   

   4. 100 kΩ 10 k Ω

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Z_if = Z_i (1 + βA) = 1 k (1 + 100 × 0.99) = 100 kΩ
   

   Zof =	Z0	=	100	= 1 Ω
   	1 + βA		100

   
   

   Correct Option: C

   Z_if = Z_i (1 + βA) = 1 k (1 + 100 × 0.99) = 100 kΩ
   

   Zof =	Z0	=	100	= 1 Ω
   	1 + βA		100

   
   

---

112. In the circuit shown in the given figure, the type of feedback used is
     
     

1. 1. voltage series feedback

   
   
   

   2. voltage shunt feedback

   
   
   

   3. current series feedback

   
   
   

   4. current shunt feedback

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

---

---

113. In the single-stage transistor amplifier circuit shown in the given figure, if capacitor C_E is removed, then, ac small-signal midband voltage gain of the amplifier
     
     

1. 1. increases

   
   
   

   2. decreases

   
   
   

   3. is unaffected

   
   
   

   4. drops to zero

   
   
   

---

1. View Hint View Answer Discuss in Forum

   
   With C_E, voltage gain
   

   Aυ = -	-hfeRL
   	hie + (1 + hfe)RE

   
   If R_E by passed with capacitor C_E, A_V will increase Hence, after removing C_E mid band voltage gain decreases.

   Correct Option: B

   
   With C_E, voltage gain
   

   Aυ = -	-hfeRL
   	hie + (1 + hfe)RE

   
   If R_E by passed with capacitor C_E, A_V will increase Hence, after removing C_E mid band voltage gain decreases.

---

114. If an input signal with non-zero dc component is applied to a low pass RC network, then dc component in the output will be
     
     

1. 1. same as that in the input

   
   
   

   2. less than that in the input

   
   
   

   3. more than that in the input

   
   
   

   4. zero

   
   
   

---

1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

---

---

115. A junction transistor operating at room temperature with I_C = 2 mA, where (kT / q) = 20 mV and β = 100. The values of parameter g_m in mhos and r_π in ohm respectively are
     

1. 1. 0.04 and 2500

   
   
   

   2. 0.08 and 1250

   
   
   

   3. 0.5 and 800

   
   
   

   4. 0.08 and 5000

   
   
   

---

1. View Hint View Answer Discuss in Forum

   gm =	IC	=	2	= 0.08
   	VT		25

   
   

   rm =	β	=	100	= 1250
   	gm		0.08

   Correct Option: B

   gm =	IC	=	2	= 0.08
   	VT		25

   
   

   rm =	β	=	100	= 1250
   	gm		0.08

---