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Electronics and Communication Engineering - Electronic Devices and Circuits

Exercise : Electronic Devices and Circuits - Section 3
26.

Assertion (A): TTL is a very popular logic in SSI and MSI category.

Reason (R): In Schottky TTL the power dissipation is less than in ordinary TTL.

Both A and R are correct and R is correct explanation of A
Both A and R are correct but R is not correct explanation of A
A is true, R is false
A is false, R is true
Answer: Option
Explanation:

In Schottky TTL storage time is reduced.

27.
FF16 when converted to 8421BCD =
0000 0101 0101
0010 0101 0101
1111 0101 0101
1000 0101 0101
Answer: Option
Explanation:

FF in hexadecimal = 15 x 16 + 15 = 255 in decimal = 0010 0101 0101 in BCD.

28.
ECL has high switching speed because the transistors are
switching between cutoff and saturation regions
switching between cutoff and active regions
switching between active and saturation regions
none of the above
Answer: Option
Explanation:

High speed is obtained because saturation state is avoided.

29.
Karnaugh map can not be drawn when the number of variables is more than 4
True
False
Answer: Option
Explanation:

K map can be drawn for more than 4 variables.

30.
A dynamic RAM cell which holds 5 V has to be refreshed every 20 ms so that the stored voltage does not fall by more than 0.5 V. If the cell has a constant discharge current of 0.1 pA, the storage capacitance of cell is
4 x 10-6 F
4 x 10-9 F
4 x 10-12 F
4 x 10-15 F
Answer: Option
Explanation:

Q = 20 x 10-3 x 0.1 x 10-12 = 2 x 10-15 C and .

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