21. How many Flip-Flops are required for mod–16 counter?
a. 5
b. 6
c. 3
d. 4
Answer: (d).4

22. The digital logic family which has minimum power dissipation is
a. TTL
b. RTL
c. DTL
Answer: (d).CMOS

23. Data can be changed from special code to temporal code by using
a. Shift registers
b. counters
c. Combinational circuits
d. A/D converters
Answer: (a).Shift registers

24. A ring counter consisting of five Flip-Flops will have
a. 5 states
b. 10 states
c. 32 states
d. Infinite states
Answer: (a).5 states

25. The speed of conversion is maximum in
a. Successive-approximation A/D converter
b. Parallel-comparative A/D converter
c. Counter ramp A/D converter
d. Dual-slope A/D converter
Answer: (b).Parallel-comparative A/D converter

26. The gates required to build a half adder are
a. EX-OR gate and NOR gate
b. EX-OR gate and OR gate
c. EX-OR gate and AND gate
d. Four NAND gates
Answer: (c).EX-OR gate and AND gate

27. If the input to T-flipflop is 100 Hz signal, the final output of the three T-flipflops in cascade is
a. 1000 Hz
b. 500 Hz
c. 333 Hz
d. 12.5 Hz
Answer: (d).12.5 Hz

28. The device which changes from serial data to parallel data is

29. A device which converts BCD to Seven Segment is called
a. Encoder
b. Decoder
c. Multiplexer
d. Demultiplexer
Answer: (b).Decoder

30. The access time of ROM using bipolar transistors is about
a. 1 sec
b. 1 msec
c. 1 µsec
d. 1 nsec
Answer: (c).1 µsec

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