Electrical Engineering - Digital System
Exam Duration: 45 Mins Total Questions : 30
Given \({ \left( 125 \right) }_{ R }={ \left( 203 \right) }_{ 5 }\). The value of radix R will be
- (a)
16
- (b)
10
- (c)
8
- (d)
6
Which one of the following is a coincidence logic circuit?
- (a)
- (b)
- (c)
- (d)
A logical expression in the sum of products (SOP) is suitable for implementation using
- (a)
AND gates
- (b)
NOR gates
- (c)
NAND gates
- (d)
EX-OR gates
The network shown in figure implements
- (a)
NOR gate
- (b)
NAND gate
- (c)
XOR gate
- (d)
XNOR gate
Two stages of two four decoders are shown in figure
The expression for \({ I }_{ 0 }',{ I }_{ 1 }',{ I }_{ 2 }'\) and \({ I }_{ 3 }'\) is
- (a)
\({ I }_{ 0 }'=0\quad { I }_{ 1 }'={ I }_{ 1 }\bigoplus { I }_{ 2 }\quad { I }_{ 2 }'={ I }_{ 1 }\bigodot { I }_{ 2 }\quad { I }_{ 3 }'=0\)
- (b)
\({ I }_{ 0 }'=1\quad { I }_{ 1 }'={ I }_{ 1 }\bigoplus { I }_{ 2 }\quad { I }_{ 2 }'={ I }_{ 1 }\bigodot { I }_{ 2 }\quad { I }_{ 3 }'=1\)
- (c)
\({ I }_{ 0 }'=1\quad { I }_{ 1 }'={ I }_{ 1 }\bigodot { I }_{ 2 }\quad { I }_{ 2 }'={ I }_{ 1 }\bigoplus { I }_{ 2 }\quad { I }_{ 3 }'=1\)
- (d)
\({ I }_{ 0 }'=0\quad { I }_{ 1 }'={ I }_{ 1 }\bigodot { I }_{ 2 }\quad { I }_{ 2 }'={ I }_{ 1 }\bigoplus { I }_{ 2 }\quad { I }_{ 3 }'=0\)
The network shown in figure implements
- (a)
NOR gate
- (b)
NAND gate
- (c)
XOR gate
- (d)
XNOR gate
A certain J-K flip-flop has tnd =12 ns. The largest MOD ripple counter that can be constructed from these flip-flops and still operate upto 10 MHz is
- (a)
8
- (b)
256
- (c)
512
- (d)
10
What memory address range is not represented by chip #1 and chip #2 in the figure? A0 to A15 in this figure are the address lines and CS means chip select.
- (a)
0100-02FF
- (b)
1500-16FF
- (c)
F900-FAFF
- (d)
F800-F9FF
For the 4 bit DAC shown in the figure the output voltage Vo is
- (a)
10 V
- (b)
5 V
- (c)
4 V
- (d)
8 V
The address bus width of a memory of size 1024 \(\times \) 8 bit is
- (a)
8 bit
- (b)
10 bit
- (c)
13 bit
- (d)
15 bit
The simplified form of the logic circuit shown in figure below is
- (a)
- (b)
- (c)
- (d)
For a sequence generator to generate a sequence 101010111 ... The maximum number of flip-flops required are
- (a)
4
- (b)
3
- (c)
5
- (d)
None of these
The number of comparisons carried out in a 4 bit flash type A/D converter is
- (a)
16
- (b)
15
- (c)
4
- (d)
3
Which of the following identity is true?
- (a)
\(A+BC=\left( \overline { A } +B \right) \left( \overline { A } +C \right) \)
- (b)
\(A+BC=\left( \overline { A } +B \right) \left( A+C \right) \)
- (c)
\(A+BC=\left( \overline { A } +B \right) \left( \overline { A } +B \right) \)
- (d)
\(A+BC=(A+B)(A+C)\)
Without any additional circuitry, an 8:1 MUX can be used to obtain
- (a)
some but not all Boolean functions of 3 variables
- (b)
all functions of 3 variables but none of 4 variables
- (c)
all functions of 3 variables and some but not all of 4 variables
- (d)
all functions of 4 variables
Match counters given in List-I with a number of states given in List-II and select the correct answer using the codes given below the lists.
List I | List II |
---|---|
P. Ripple counter | 1. 2N |
Q. Johnson counter | 2. N |
R. Ring counter | 3. 2N |
S. Sequence counter | 4. 2N-1 |
- (a)
P Q R S 1 3 2 4 - (b)
P Q R S 1 3 2 1 - (c)
P Q R S 1 2 3 4 - (d)
P Q R S 4 1 2 3
The Boolean function f implemented in figure using two input multiplexers is
- (a)
\(A\overline { B } C+AB\overline { C } \)
- (b)
\(\overline { A } BC+\overline { A } B\overline { C } \)
- (c)
\(\overline { A } BC+\overline { A } \overline { B } \overline { C } \)
- (d)
\(\overline { A } \overline { B } C+\overline { A } B\overline { C } \)
In the given network of AND and OR gates, it can be written as
- (a)
\({ x }_{ 0 }{ x }_{ 1 }{ x }_{ 2 }...{ x }_{ n }+{ x }_{ 1 }{ x }_{ 2 }...{ x }_{ n }+{ x }_{ 2 }{ x }_{ 3 }...{ x }_{ n }\)
- (b)
\({ x }_{ 0 }{ x }_{ 1 }+{ x }_{ 2 }{ x }_{ 3 }+...{ x }_{ n-1 }...{ x }_{ n }\)
- (c)
\({ x }_{ 0 }{ x }_{ 1 }{ x }_{ 3 }...{ x }_{ n-1 }+{ x }_{ 2 }{ x }_{ 3 }{ x }_{ 5 }...{ x }_{ n-1 }+...+{ x }_{ n-2 }{ x }_{ n-1 }+{ x }_{ n }\)
- (d)
\({ x }_{ 0 }+{ x }_{ 1 }+{ x }_{ 2 }+...+{ x }_{ n }\)
A sequential circuit using D flip-flop and logic gates is shown below, where X and Y are inputs and Z is the output. Then, the circuit is
- (a)
J-K flip-flop with inputs X=J and Y=K
- (b)
S-R flip-flop with inputs X=R and Y=S
- (c)
S-R flip-flop with inputs X=S and Y=R
- (d)
J-K flip-flop with inputs X=K and Y=J
Suppose propagation delay time of flip-flop is 0.2 ns and it is followed by 2 decoders with a propagation delay time of 0.1 ns each. The time required for data input to settle before the
triggering edge of the clock is 2 ns and the time for which data remains stable is just 1 ns. Then, maximum operating frequency of flip-flop will be
- (a)
434 MHz
- (b)
400 MHz
- (c)
294 MHz
- (d)
450 MHz
The minimal product of sums function described by the K-map given in figure.
- (a)
\(\overline { A } \overline { C } \)
- (b)
\(\overline { A } +\overline { C } \)
- (c)
A+C
- (d)
AC
For the circuit shown in figure, the Boolean expression for the output Y in terms of inputs P, Q, R and S is
- (a)
\(\overline { P } +\overline { Q } +\overline { R } +\overline { S } \)
- (b)
P+Q+R+S
- (c)
\((\overline { P } +\overline { Q } )(\overline { R } +\overline { S } )\)
- (d)
(P+Q)(R+S)
A memory system has a total of 8 memory chips, each with 12 address lines and 4 data lines. The total size of the memory system is
- (a)
6 kbyte
- (b)
32 kbyte
- (c)
48 kbyte
- (d)
64 kbyte
Select the circuit, which will produce the given output Q for the input signals X, and X 2 given in figure
- (a)
- (b)
- (c)
- (d)
Determine the aperture time for 2 kHz signal using a 4 bit ADC, where input sine wave amplitude equals the maximum input for ADC.
- (a)
2.66 \(\mu s\)
- (b)
5.31 \(\mu s\)
- (c)
5.31 ns
- (d)
10.62 ns
An OR gate has 6 inputs. How many input words are there in its truth table?
- (a)
6
- (b)
36
- (c)
64
- (d)
64000
The two numbers represented in signed 2's complement form are P=11101101 and Q =11100110. If Q is subtracted from P, the value obtained 11 signed 2's complement form is
- (a)
100000111
- (b)
00000111
- (c)
11111001
- (d)
111111001
Consider the given figure:
The value of Z is
- (a)
ABC
- (b)
\(\overline { A } \overline { B } C\)
- (c)
zero
- (d)
\(\overline { A } BC\)
A switching function of four variables, f(w, x, y, z) is equal I to the product of two other functions f1 and f2 , of the same variable f = f1 f2· The functions f and f1 are as follow:
\(f=\sum { m(4,7,15) } \\ f=\sum { m(0,1,2,3,4,7,8,9,10,11,15) } \)
The number of full specified function that will satisfy the given condition, is
- (a)
32
- (b)
16
- (c)
4
- (d)
1
The 8 bit left shift register and D flip-flop shown in the figure is synchronized with the same clock. The D flip-flop is initially cleared.
If initially, register contains byte B7, then after 4 clock pulse contents of register will be
- (a)
73
- (b)
72
- (c)
7E
- (d)
74