What Are Sequential Circuits?
Sequential circuits are logic circuits that you use when the output depends on both current inputs and previous states. These kinds of circuits include input variables (X), logic gates, and output variables (Z). You often work with examples like flip-flops, counters, registers, and clocks in digital systems.
Asynchronous sequential circuits
Asynchronous sequential circuits do not use clock signals. Instead, they operate through pulses, allowing changes in the input to directly affect the circuit’s state. The internal state of the circuit changes whenever the input variable changes. The memory elements in asynchronous sequential circuits are un-clocked flip-flops or time-delayed elements. These circuits bear similarities to combinational circuits with feedback.
Synchronous sequential circuits
On the other hand, in synchronous sequential circuits, the synchronization of the memory element’s state is achieved through the clock signal. The output is stored in flip-flops or latches, which serve as memory devices. The synchronization of the outputs occurs either with only the negative edges or only the positive edges of the clock signal.
In summary, asynchronous sequential circuits operate without clock signals, while synchronous sequential circuits rely on clock signals to synchronize their memory elements and outputs.
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