106. As compared to power MOSFET, a BJT has—

1. 1. Lower switching losses but higher conduction loss

   
   
   

   2. Higher switching losses but higher conduction loss

   
   
   

   3. Higher switching losses but lower conduction loss

   
   
   

   4. Lower switching losses and lower conduction loss

   
   
   

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1. View Hint View Answer Discuss in Forum

   As compared to power MOSFET, a BJT has higher switching losses but lower conduction losses.

   Correct Option: C

   As compared to power MOSFET, a BJT has higher switching losses but lower conduction losses.

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107. The drain current of a MOSFET in saturation is given by I_D = K (V_{G S} – V_T)² where K is a constant. The magnitude of the transconductance g_m is—

1. 1. 	K (VGS – VT)2
      	VDS

   
   
   

   2. 2K (V_GS – V_T)

   
   
   

   3. 	ID
      	VGS – VDS

   
   
   

   4. 	K (VGS – VT)2
      	VGS

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given, I_D = K (V_GS – V_T) ²
   Where K is constant
   

   gm =		∂ID	≈	∂	K(VGS – VT) 2
   		∂VGS		∂VGS

   
   or g_m = 2K (V_GS – V_T)
   Hence alternative (B) is the correct choice.

   Correct Option: B

   Given, I_D = K (V_GS – V_T) ²
   Where K is constant
   

   gm =		∂ID	≈	∂	K(VGS – VT) 2
   		∂VGS		∂VGS

   
   or g_m = 2K (V_GS – V_T)
   Hence alternative (B) is the correct choice.

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108. An n-channel JFET having a pinch-off voltage V_P of – 5V shows a transconductance g_m of 1 mA/V when the applied gate to source voltage is – 3V. Its maximum transconductance in (mA/V) will be—

1. 1. 1·5

   
   
   

   2. 2·0

   
   
   

   3. 2·5

   
   
   

   4. 3·0

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given, g_m = 1 mA/V, V_p = – 5V, V_GS = – 3V, g_mo =?
   

   We know that gm = gmo		1 -	VGS
   			Vp

   
   Where, g_mo = maximum transconductance
   
   

   1 = gmo		1 -		- 3
   				- 5

   
   
   

   or 1 = gmo			5 - 3
   			5

   
   

   or gmo =	5	= 2·5 mA/V
   	2

   
   Hence alternative (D) is the correct choice.

   Correct Option: C

   Given, g_m = 1 mA/V, V_p = – 5V, V_GS = – 3V, g_mo =?
   

   We know that gm = gmo		1 -	VGS
   			Vp

   
   Where, g_mo = maximum transconductance
   
   

   1 = gmo		1 -		- 3
   				- 5

   
   
   

   or 1 = gmo			5 - 3
   			5

   
   

   or gmo =	5	= 2·5 mA/V
   	2

   
   Hence alternative (D) is the correct choice.

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109. The effective channel length of a MOSFET in saturation decreases with increase in—

1. 1. Gate voltage

   
   
   

   2. Drain voltage

   
   
   

   3. Source voltage

   
   
   

   4. Body voltage

   
   
   

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1. View Hint View Answer Discuss in Forum

   The effective channel length of a MOSFET in saturation decreases with increase in drain voltage.

   Correct Option: B

   The effective channel length of a MOSFET in saturation decreases with increase in drain voltage.

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110. MOSFET can be used as—

1. 1. Current controlled capacitor

   
   
   

   2. Voltage controlled capacitor
      

   
   
   

   3. Current controlled inductor

   
   
   

   4. Voltage controlled inductor

   
   
   

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1. View Hint View Answer Discuss in Forum

   MOSFET can be used as voltage controlled capacitor.

   Correct Option: B

   MOSFET can be used as voltage controlled capacitor.

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