What is Race-Around condition in a J-K flip-flop? Explain how it occurs. How can a D flip-flop be implemented using a J-K flip-flop.Īns. D flip-flop can be implemented by connecting an inverter between inputs J and K, as shown in the Fig. The hold time (t H) is the time interval immediately following the active edge (transition) of the CLK signal during which the synchronous control input must be maintained at the proper level.Ģ0. Define set-up time and hold-time for a clocked flip-flop.Īns. The set-up time (t s) is the time interval immediately preceding the active edge (transition) of the CLK signal during which the control input must be maintained at the proper level. There are two types of edge triggering, as shown in the Fig. The data inputs are the binary information that affect the state of the FF.Īns. Edge triggering means activation of the clock input on the transitions of the clock pulse (edges of the clock pulse) rather than the entire duration of the clock pulse (levels of the clock pulse). The clock pulse is an activating signal that triggers the FF for operation. What two types of input does a clocked flip-flop have?Īns. A clocked FF has two types of inputs-clocked pulse input and data input. In other words sequential logic circuit may be defined as that logic circuit whose outputs are determined by the sequence in which input signals are applied.Īns. A flip-flop is a basic memory element that is made of an assembly of logic gates and is used to store 1-bit of information.Īns. It is a D-type of flip-flop and stores one bit of data.Īns. Excitation table gives an information about what should be the flip-flop inputs if the outputs are specified before and after the clock pulses.Īns. State table consists of complete information about present state, next state, and outputs of a sequential circuit.ġ7. What are the applications of multiplexer?Īns. Multiplexer have the applications of (i) data selection and routing (ii) operation sequencing, (iii) waveform generation, (iv) logic function generation, (v) parallel to serial conversion.Īns. Sequential logic circuit is that circuit in which outputs of the circuit remain in their state, until instructed to change it. What is the logic signal required to inhibit a NAND gate and what is its output when inhibited?Īns. Logic 0 is the logic signal required to inhibit a NAND gate and 1 is its output, irrespective of all other inputs, when inhibited.Īns. Multiplexing is an operation performed with digital logic circuits called multiplexers and allows information to be switched from several lines into a single line in a specified sequence.Īns. An encoder is a logic circuit that produces coded binary outputs from uncoded inputs.Īns. Demultiplexer is a logic circuit that accepts one data input and distributes it over several outputs.Īns. Decoder is a logic circuit that decodes from binary to octal, decimal, hexadecimal, or any other code such as 7-segment circuit etc.ġ1. fall under the category of sequential circuits.Īns. A logic circuit, that can add two 1-bit numbers and produce outputs for sum and carry, is called a half-adder.Īns. A binary adder, which can add two 1-bit binary numbers along with a carry bit and produces outputs for sum and carry is called a full-adder.Ħ. In sequential logic circuits, stored output is applied to logic gates at proper places in circuits with feedback connections, therefore, such circuits are driven not only by the externally applied inputs but by the feedback signals also.Īdder, subtractor, encoder, decoder, MUX, DEMUX etc, fall under the category of combinational circuits, while FFs, counters etc. In sequential logic circuits, output states of the circuits remain in their state, until instructed to change it, so it can be said that these circuits possess memory, while in combinational logic circuits, output state changes with the change in input state. A sequential logic circuit contains storage elements in addition to logic gates. A combinational logic circuit contains logic gates only but does not contain storage elements. Clearly differentiate between the following concept : Combinational and sequential circuits.Īns. Logic circuit may be classified into two categories i.e., combinational logic circuits and sequential logic circuits. A combinational circuit will always respond in the same fashion to input function, when we apply signal to the input terminal of the combinational logic circuit.ģ.In combinational circuits, the output exists as long as the input exists.Write two characteristics of combinational circuits.Īns. The two characteristics of combinational circuits are: The combinational circuit has no memory element. Ans. In a combinational circuit, the output depends upon present input(s) only i.e., not dependent on the previous input(s).
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