Q- Implement the Octal to Binary encoder (only first 8 numbers). Ans: In this circuit, we have 8 inputs and 3 outputs. The octal number is feed into the encoder by placing a high (1) on the corresponding line and we get the binary equivalent as output. From the above truth table we can easily get […]
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Encoder
This digital circuit does exact opposite of the function of a decoder. It converts the information from 2 n to n lines. The truth table is: We can easily design the circuit diagram from this table. How ever if mistakenly we have ‘1’ at two of the inputs then we’ll have wrong answer from the circuit. But […]
Demultiplexer
It is a combinational circuit which receives 1-bit information and puts this information on the line which is selected by the binary input on the selection lines. This is different from decoder circuit as there is also an information line and we don’t have to put 1 every time on output (as in decoder) but […]
Q: HIGHER DECODER from LOWER DECODERS
Q- Obtain a 4 to 16 decoder using (a) 2 to 4 decoder (b) 3 to 8 decoder Ans: (a) we take abcd2 as the input to the decoder. Following is the diagram to design 4 to 16 decoder using 2 to 4 decoders When we have a=0 b=0 then top most decoder is enabled and 1 […]
Q: Implement Full Adder using DECODER
Q- Implement the Full adder using 3 to 8 decoder. Ans: equation for sum S = ab’c’ + a’b’c + a’bc’ + abc = Σ(1,2,4,7) C = ab + ac + bc = ab(c + c’) + ac (b + b’) + bc (a + a’) = abc + abc’ + abc + ab’c + […]
Decoders
n to m decoder is the combinational circuit which convert binary information from n lines of input to m lines of output and m=<2 n. Let’s have an example of 3 to 8 decoder. This encoder just puts the 1 on the line which is equal to the decimal equivalent of binary number abc2 at the […]
Q2: Obtaining HIGHER COMPARATOR using LOWER COMPARATOR
Q- Implement the function of 10-bit comparator using 4-bit comparators. Ans: We can implement this as follow:
Obtaining HIGHER COMPARATOR using LOWER COMPARATORS
Q-Can we implement higher comparator 4-bit comparator using 2-bit comparators. Ans: Yeswe can implement the above required as follow: Firstly lower two bits of A & B are compared and then next bits and then next. We feed the result of first 2 bits to lower bit of next comparator. Then we feed the result […]
2-bit COMPARATOR
Similarly we can have 2 bit comparator and the table to list all the combinations at input and their corresponding outputs is as: A B f (A>B) f (A=B) f (A<B) 00 00 0 1 0 01 00 1 0 0 10 00 1 0 0 11 00 1 0 0 00 01 0 0 […]
1 bit COMPARATORS
Here we’ll be designing circuits to compare different binary numbers. Suppose we have two numbers A & B at the input and 3 output as A>B, A=B, A<B and only one of the three outputs would be high accordingly if A is greater than or equal to or less than B. 1-bit comparator: Let’s begin with […]