Why sequential circuits

The asynchronous sequential circuit is similar to the combinational circuits with feedback. In synchronous sequential circuits, synchronization of the memory element's state is done by the clock signal. The output is stored in either flip-flops or latches memory devices. The synchronization of the outputs is done with either only negative edges of the clock signal or only positive edges.

When ON time and OFF time of the clock signal are the same, a square wave is used to represent the clock signal. Below is a diagram which represents the clock signal:. A clock signal is considered as the square wave. Sometimes, the signal stays at logic, either high 5V or low 0V, to an equal amount of time. The logic High and logic Low are the two levels in the clock signal. In level triggering, when the clock pulse is at a particular level, only then the circuit is activated.

There are the following types of level triggering:. In a positive level triggering, the signal with Logic High occurs. So, in this triggering, the circuit is operated with such type of clock signal.

Below is the diagram of positive level triggering:. In negative level triggering, the signal with Logic Low occurs. Below is the diagram of Negative level triggering:.

In clock signal of edge triggering, two types of transitions occur, i. The transition from Logic Low to Logic High occurs in the clock signal of positive edge triggering. So, in positive edge triggering, the circuit is operated with such type of clock signal. Like Article. Next Flip-flop types, their Conversion and Applications.

Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert. Writing code in comment? An electronic oscillator is an electronic circuit that produces periodic, oscillating signals. An oscillator converts direct current from a power supply to an alternating current signal.

An oscillator is an amplifier which provides feedback with an input signal. It is a non-rotating device to produce alternating current. Enough power must be fed back to the input circuit for the oscillator to drive itself. The feedback signal in the oscillator is regenerative. The oscillators that give an output as a sine wave are called as sinusoidal oscillators. These oscillators can provide the output at frequencies ranging from 20Hz to GHz.

Depending on the material or components used in oscillator, Sinusoidal oscillators are further classified into four types. Non-sinusoidal oscillators provide output in the form of a square, rectangular or sawtooth waveform.

These oscillators can provide an output at frequencies ranging from 0 to 20MHz. This is all about the sequential circuits. The sequential circuits are the circuits, where the immediate value of outputs depends on the immediate values of inputs and also on states they were in previously. They contain memory blocks for storing the previous state of the circuit. Furthermore, any queries regarding this article or any help in implementing electrical and electronics projects, you can approach us by commenting in the comment section below.

This is analogous to sequential circuits which changes their state according to the previous and present signals. Back to top. Combinational Circuits Sequential Circuits Output depends only on the present value of the inputs.

Output depends on both the present and previous state values of the inputs These circuits will not have any memory as their outputs change with the change in the input value. Sequential circuits have some sort of memory as their output changes according to the previous and present values. There are no feedbacks involved. In a sequential circuit the outputs are connected to it as a feedback path.

Used in basic Boolean operations. Used in the designing of memory devices. Implemented in: Half adder circuit, full adder circuit, multiplexers, demultiplexers, decoders and encoders.

Implemented in: RAM, Registers, counters and other state retaining machines. The clock signal plays a crucial role in sequential circuits. A clock is a signal, which oscillates between logic level 0 and logic level 1, repeatedly. Square wave with constant frequency is the most common form of clock signal. These are the instants at which the clock changes from 0 to 1 a positive edge or from 1 to 0 a negative edge.

Clock signals control the outputs of the sequential circuit. That is it determines when and how the memory elements change their outputs. If a sequential circuit is not having any clock signal as input, the output of the circuit will change randomly. So that they cannot retain their state till the next input signal arrives.

But sequential circuits with clock input will retain its state till the next clock edge occurs. Classification of Sequential Circuits Based on the clock signal input, the sequential circuits are classified into two types. In Synchronous sequential circuit, the output depends on present and previous states of the inputs at the clocked instances. The circuits use a memory element to store the previous state.

The memory elements in these circuits will have clocks. All these clock signals are driven by the same clock signal. These are used when speed of operation is important.