121. For given MOD-16 counter with a 10 MHz clock input. Determine the frequency at Q3 —
     
     
     
     

1. 1. 625 kHz
      

   
   
   

   2. 62.5 kHz
      

   
   
   

   3. 10 MHz
      

   
   
   

   4. 5 MHz

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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122. A certain JK flip-flop has tpd = 12 n sec. What is the largest MOD counter, that can be constructed from these FFs and still operate upto 10 MHz?
     

1. 1. 16
      

   
   
   

   2. 64
      

   
   
   

   3. 128
      

   
   
   

   4. 256

   
   
   

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1. View Hint View Answer Discuss in Forum

   f ≤	1
   	ntpd

   
   

   or MHz ≤	1
   	n × 12 × 10-9

   
   

   or 10×106 ≤	1
   	n × 12 × 10-9

   
   

   or n ≥	1000
   	120

   
   or n ≥ 8.33 or n = 8
   The largest MOD counter = 2⁸ = 256.

   Correct Option: D

   f ≤	1
   	ntpd

   
   

   or MHz ≤	1
   	n × 12 × 10-9

   
   

   or 10×106 ≤	1
   	n × 12 × 10-9

   
   

   or n ≥	1000
   	120

   
   or n ≥ 8.33 or n = 8
   The largest MOD counter = 2⁸ = 256.

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123. Minimum number of JK flip-flops are needed to construct a BCD counter is—
     

1. 1. 2
      

   
   
   

   2. 4
      

   
   
   

   3. 8
      

   
   
   

   4. 6
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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124. The maximum frequency at which a MOD-16 ripple counter using four JK flip-flops with propagation delay time of 50 ns is—
     

1. 1. 4 MHz
      

   
   
   

   2. 5 MHz
      

   
   
   

   3. 3.2 MHz
      

   
   
   

   4. 320 MHz

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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125. The minimum number of flip-flops required to construct a MOD-64 (divide by 64) ripple counter, are—
     

1. 1. 4 flip-flops
      

   
   
   

   2. 6 flip-flops
      

   
   
   

   3. 16 flip-flops
      

   
   
   

   4. 64 flip-flops
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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