Question 1

A JK flip flop has tpd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is

Accepted Answer

Number of flip-flops = = 8.333 say 8 Modulus = 28 = 256.

Question 2

Maxterm designation for A + B + C is

Accepted Answer

A + B + C = 000 = M0 .

Question 3

In the expression A + BC, the total number of minterms will be

Accepted Answer

The min terms are ABC + ABC + AB C + ABC + ABC.

Question 4

A carry look ahead adder is frequently used for addition because

Accepted Answer

In look ahead carry adder the carry is directly derived from the gates when original inputs are being added. Hence the addition is fast. This process requires more gates and is costly.

Question 5

A decade counter skips

Accepted Answer

A decade counter counts from 0 to 9. It has 4 flip-flops. The states skipped are 10 to 15 or 1010 to 1111.

Question 6

Minimum number of 2-input NAND gates required to implement the function F = (x + y) (Z + W) is

Accepted Answer

F = (x + y) (z + w) = xy.(z + w) = xyz + xyw = minimum no. of 2 input NAND gate.

Question 7

The basic storage element in a digital system is

Accepted Answer

Storing can be done only in memory and flip-flop is a memory element.

Question 8

A counter type A/D converter contains a 4 bit binary ladder and a counter driven by a 2 MHz clock. Then conversion time

Accepted Answer

Question 9

Decimal 43 in hexadecimal and BCD number system is respectively.

Accepted Answer

(43)10 = (2B)16 (43)10 = (01000011)2 .

Question 10

Decimal number 10 is equal to binary number

Accepted Answer

1010 = 8 + 2 = 10 in decimal.

Digital Electronics Questions