Tuesday, March 17, 2015

GATE 2015 ECE Digital Circuits (Digital Electronics) - Video Solutions

GATE 2015 ECE – Questions on Digital Circuits with Solutions
1. The circuit shown consists of JK flip flops, each with an active LOW asynchronous reset. The counter corresponding to this circuit is ___________

a. Mod – 5 binary UP counter
b. Mod – 6 binary DOWN counter
c. Mod – 5 binary DOWN counter
d. Mod – 6 binary UP counter
Answer:A
Solution: https://www.youtube.com/watch?v=nSMpwmgMQNc


2. In the circuit shown, D1, D2 and D3 are ideal and inputs E1, E2 and E3 are 0 volts for logic’0’ and 10 volts for logic ‘1’. What logic gate does the circuit represent?

a. 3 input OR gate
b. 3 input NOR gate
c. 3 input AND gate
d. 3 input XOR gate
Answer:C
Solution: https://www.youtube.com/watch?v=lA-egB6GmAo


3. A universal gate can implement any Boolean function by connecting sufficient number of them appropriately. Three gates are shown.

Which one of the following statements is TRUE?
a. Gate 1 is universal gate
b. Gate 2 is universal gate
c. Gate 3 is universal gate
d. None of the gates shown is universal gate
Answer:D
Solution: https://www.youtube.com/watch?v=hJ2MSI9840A


4. A three bit pseudo random number generator is shown. Initially the value of output Y = Y2Y1Y0 is set to 111. The value of output Y after three clock cycles is _________

a. 000
b. 001
c. 010
d. 100
Answer:D
Solution: https://www.youtube.com/watch?v=yeKpE3yuXAk


5. An SR latch is implemented using TTL gates as shown in the figure. The set and reset pulse inputs are provided using the push button switches. It is observed that the circuit fails to work as desired. The SR latch can be made functional by changing

a. NOR gates to NAND gates
b. Inverters to Buffers
c. NOR gates to NAND gates and inverters to buffers
d. 5 volts to ground
Answer:D
Solution: https://www.youtube.com/watch?v=tmpeSu-gXZQ


6. Consider a four bit Digital to Analog converter. The analog value corresponding to a digital signals of values 0000 and 0001 are 0 volts and 0.0625 volts respectively. The analog value (in volts) corresponding to the digital signal 1111 is ______________
Answer:0.9375
Solution: https://www.youtube.com/watch?v=m5TBDdQ7Uwg


7. In a 8085 microprocessor, the shift registers which store the result of an addition and the overflow bit are respectively
a. B and F
b. A and F
c. H and F
d. A and C
Answer:B
Solution: https://www.youtube.com/watch?v=MSKB0ExFE9g


8. A 16 KB memory array is designed as a square with an aspect ratio of one (number of rows is equal to the number of columns). The minimum number of address lines needed for the row decoder is ______________
Answer:7
Solution: https://www.youtube.com/watch?v=Dmj_YCiX7uE


9. A 3 input majority gate is defined by the logic function M(a,b,c) = ab + bc + ca. Which one of the following gate is represented by the function M(M’(a,b,c),M(a,b,c’),c)?
a. 3 input NAND gate
b. 3 input XOR gate
c. 3 input NOR gate
d. 3 input XNOR gate
Answer:B
Solution: https://www.youtube.com/watch?v=e4wDfHig2cc


10. The Boolean expression F(x,y,z) = x’yz’+xy’z’+xyz’+xyz converted into canonical product of sum (POS) form is ___________

Answer:A
Solution: https://www.youtube.com/watch?v=wFow-s9t4Kw


11. All the logic gates shown in the figure have a propagation delay of 20 ns. Let A=C=0 and B=1 until time t = 0. At t = 0, all the inputs flip (i.e. A=C=1 and B=0) and remain in that state. For t>0, output z=1 for a duration (in 20 ns) of____________

Answer:40
Solution: https://www.youtube.com/watch?v=KywM3DmY8i0


12. A Mod-N counter using a synchronous binary UP counter with asynchronous clear input is shown in the figure. The value of N is_______________

Answer:7
Solution: https://www.youtube.com/watch?v=Cn3ylcDYyug


13. In the figure shown, the output Y is required to be Y = AB+C’D’. The gates G1 and G2 must be _____

a. NOR, OR
b. OR, NAND
c. NAND, OR
d. AND, NAND
Answer:A
Solution: https://www.youtube.com/watch?v=sjtdMcvFqDU


14. In an 8085 microprocessor, which one of the following instructions changes the content of the accumulator?
a. MOV B,M
b. PCHL
c. RNZ
d. SBI BEH .
Answer:D
Solution: https://www.youtube.com/watch?v=_VVI3E46Nag


15. A function of Boolean variables X,Y and Z is expressed in terms of the min-terms as F(X,Y,Z) = ∑m(1,2,5,6,7). Which one of the product of sums given below is equal to the given function?

Answer:B
Solution: https://www.youtube.com/watch?v=HPihAxUd608


16. The figure shows a binary counter with synchronous clear input. With the decoding logic shown, the counter works as a _______________

a. Mod – 2 counter
b. Mod – 4 counter
c. Mod – 5 counter
d. Mod – 6 counter
Answer:C
Solution: https://www.youtube.com/watch?v=UQ_-E6h7XpE


17. Problem on Design of 1 to 8 De-multiplexer using two 2 to 4 decoders with extra logic gates.

Answer:D
Solution: https://www.youtube.com/watch?v=FYl68C2-fmo

Post Your Feedback (or) Doubts here.......

Name

Email *

Message *