Synchronous and Asynchronous Sequential Circuits

SYNCHRONOUS AND ASYNCHRONOUS SEQUENTIAL CIRCUITS

INTRODUCTION

Digital electronics is classified into combinational logic and sequential logic. Combinational logic output depends on the inputs levels, whereas sequential logic output depends on stored levels and also the input levels.

The memory elements are devices capable of storing binary info. The binary info stored in the memory elements at any given time defines the state of the sequential circuit. The input and the present state of the memory element determines the output. Memory elements next state is also a function of external inputs and present state. A sequential circuit is specified by a time sequence of inputs, outputs, and internal states.

There are two types of sequential circuits. Their classification depends on the timing of their signals:

·              Asynchronous sequential circuits

·              synchronous sequential circuits