Examples of solved problems for chapter3,5,6,7,and8. Under the condition that the gain of the inverter in the transient region is larger than 1, onlya. Solved questions and answers on sequential circuits for job interviews with pdf. Logic circuits questions and answers pdf free download posted on august 19, 2018 march 20, 2019 by engineer 2 comments. Testing sequential logic vlsi questions and answers sanfoundry. Consequently the output is solely a function of the current inputs. This is the electronics questions and answers section on sequential logic circuits with explanation for various interview, competitive examination and. Leaderboard topicwise practice subjective problems difficulty level school difficulty level basic difficulty level easy difficulty level medium. Total 16 questions have been asked from combinational and sequential circuits topic of digital logic subject in previous gate papers. Practice problems on sequential circuits part 2 youtube.
Whose operations are more faster among the following. Give a precise definition of synchronous sequential circuits. The sequential circuits depend over the input value as well as the stored levels. Hence the previous state of input does not have any effect on the present state of the circuit. The generalised circuit contains a block of combinational logic which has two sets of inputs and two sets of outputs. Race around a problem is defined as below in terms of a digital circuit as the time clock pulse will remain in state 1 while both j and k inputs are equal to 1 and it will cause the output to complement and these set of states repeats until the pulse goes back to 0 called race around a problem. Sequential circuit analysis university of pittsburgh. Which constitutes the test vectors in sequential circuits. Electric circuits gate graduate aptitude test in engineering entrance exams ee electrical engineering electric circuits gate exam ee electrical engineering objective type online test questions and answers with solution, explanation, solved problems.
Digital electronics sequential circuits important short questions and answers. The functioning of serial adder can be depicted by the following state diagram. The sequential circuits are designed using the combinational circuits along with a memory devices known as flipflops. The design of combinational circuit starts from a specification of the problem. Use it as scratch paper or to provide additional answers. Flipflops, latches and counters and which themselves can be made by simply connecting together universal nand gates andor nor gates in a particular combinational way to produce the required sequential circuit. Finite state machine, state table, design of combinational logic of sequential circuit, reverse of sequential design. Analysis and synthesis of synchronous sequential circuit.
Not practical for use in synchronous sequential circuits. Electronics and communication engineering questions and answers 3 electronics instruments 1 electronics questions and answers 20. Combinational and sequential logic circuits analog and. Sr flip flop sequential circuit design book problem 435. Memory elements in synchronous circuits are flipflops which are clocked. Different types of sequential circuits basics and truth. In this course material we design and analyze only synchronous sequential logic. Asynchronous logic is more difficult to design and it has some problems compared to synchronous logic. For decoding any number output must be high for that code and this is possible in one 4input nand gate, one inverter option only. Demonstrate by example how to analyze synchronous sequential. Sequential circuit design university of pittsburgh. Written exam with solutions for ie12045 digital design. Draw a block diagram not a gatelevel diagram of a d latch and a d. Written exam ie12045 digital design monday 2310 2017.
But sequential circuit has memory so output can vary based on input. Sequential circuits an overview sciencedirect topics. This type of circuits uses previous input, output, clock and a memory element. Sequential circuits have memory because their outputs depend, in part, upon past outputs. Digital circuits questions and answers combinational. Questions and answers on sequential circuits in digital electronics. This chapter will discuss more complex sequential circuits fabricated from these basic elements. Sequential circuit 3 short questions and answers 15 signal processing 3. Introduce several structural and behavioral models for synchronous sequential circuits. Up to this point we have considered two types of circuits. State table consists of complete information about present state, next state, and outputs of a sequential circuit. Sequential logic circuits electronics questions and answers. Input signals change one at a time and only when the circuit is in the stable state. What do you mean by sequential logic circuit and combinatioal logic circuits.
We introduced standard cell technology in section 3. Sequential circuits are essentially combinational circuits with feedback. Design a sequential circuit using d flip flops and one input x. The main problem is that the digital memory is sensitive to the order that their input signals arrive them, like, if two signals arrive at a flipflop at the same time, which state the. Questions and answers on sequential circuits in digital. Electric circuits ee electrical engineering gate exam. Written exam with solutions for ie12045 digital design monday 2710 2014 9. A block diagram of a generalised sequential circuit is shown in fig. Electronics questions and answers 20 filter circuits 9 founder speaks 3 gate questions and answers 1. Digital electronics part i combinational and sequential.
In this type of logic circuits outputs depend on the current inputs and previous inputs. Sequential circuit an overview sciencedirect topics. A sequential circuit using d flip flop and logic gates is shown in figure, where x and y are the inputs and z is output. In this type of logic circuits outputs depend only on the current inputs. Design a sequential circuit detector that has one input x and one input y. A decoder is a combinational circuit that converts binary data to ncoded data upto 2 n outputs. Total 25 questions have been asked from combinational and sequential logic circuits topic of analog. Learning objectives on completion of this lesson you will be able to. Sequential logic circuits are a type of logic circuits in which its output depends on the current and last input memory. Practice problems on combinational circuits part 1. A circuit with two crosscoupled nor gates or two crosscoupled nand gates. X1 and x2 are inputs, a and b are states representing carry. What are the different types of sequential circuits.
Mention any two differences between the edge triggering and level triggering. These are defined as digital circuit whose output is dependent not only on the present input value but also on the past history of its input. Avoid to use latches as possible in synchronous sequential circuits to avoid design problems 58 sr latch. Digital logic circuits combinational circuits important short questions and answers. Combinational and sequential circuits digital logic. Finite state machine for a sequential design controller design. Both latches and flipflops are circuit elements whose output depends not only on the current inputs, but also on previous inputs and outputs.
Examples for sequential and combinational circuits answers. Homework 3, summer 2000 page 1 ececs352 department of electrical and computer engineering. The following important conjecture is easily proven to be valid. What are the applications of sequencial logic circuits. Part b design problems contains two design problems of a total of 10 points. Sequential circuit shown above starts in the state q 1 q 0. Problem gated clock width can be narrow gated clock may pass glitches of en.
Ripple counter increased delay as in ripplecarry adders delay proportional to the number of bits. Problem 1 a sequential circuit design is shown in the following diagram. Circuit,g, state diagram, state table circuits with flipflop sequential circuit circuit state diagram state table state minimizationstate minimization sequential circuit design example. Later, we will study circuits having a stored internal state, i. In this technology, circuits are built by interconnecting buildingblock cells that implement simple functions, like basic logic gates. In the last experiment, the logic circuits introduced were combinational.
Draw the state diagram from the problem statement or from the given state table. Formal sequential circuit synthesis summary of design steps assign state vectors to states. It sends an output that is dependent upon the present input in addition to the history of the input. Design a sequential circuit using d flip flops and. These circuits do not have memory cells and their output depends only upon the current value of the input.
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