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