Sequential Circuit
• It consists of a combinational circuit to which storage elements are connected to
form a feedback path.
• The binary information stored in these elements at any given time defines the state
of the sequential circuit at that time.
• The block diagram demonstrates that the outputs in a sequential circuit are a
function not only of the inputs, but also of the present state of the storage elements.
• Thus, a sequential circuit is specified by a time sequence of inputs, outputs, and
internal states .
Block Diagram of Sequential Logic Circuits
,Types of Sequential Circuit
Synchronous • A system whose behavior can be defined from the
knowledge of its signals at discrete instants of time.
• A synchronous sequential circuit employs signals that affect
Sequential the storage elements at only discrete instants of time.
• Synchronization is achieved by a timing device called a clock
Circuits
generator, which provides a clock signal having the form of a
periodic train of clock pulses .
Asynchronous • A system whose behavior depends upon the input signals at
any instant of time and the order in which the inputs change
• The storage elements commonly used in asynchronous
Sequential sequential circuits are time-delay devices.
• In gate-type asynchronous systems, the storage elements
Circuits
consist of logic gates whose propagation delay provides the
required storage.
, Synchronous Sequential Circuits
The clock pulses are distributed throughout t
system in such a way that storage elements are affect
only with the arrival of each pulse.
Sequential circuits that use clock pulses to contr
storage elements are called clocked sequential circu
and are the type most frequently encountered
practice.
The storage elements (memory) used in clock
sequential circuits are called flipflops.
A flip-flop is a binary storage device capable
storing one bit of information. In a stable state, t
output of a flip-flop is either 0 or 1.
Propagation delays play an important role
determining the minimum interval between clo
pulses that will allow the circuit to operate correctly.
Synchronous clocked sequential circuit
• It consists of a combinational circuit to which storage elements are connected to
form a feedback path.
• The binary information stored in these elements at any given time defines the state
of the sequential circuit at that time.
• The block diagram demonstrates that the outputs in a sequential circuit are a
function not only of the inputs, but also of the present state of the storage elements.
• Thus, a sequential circuit is specified by a time sequence of inputs, outputs, and
internal states .
Block Diagram of Sequential Logic Circuits
,Types of Sequential Circuit
Synchronous • A system whose behavior can be defined from the
knowledge of its signals at discrete instants of time.
• A synchronous sequential circuit employs signals that affect
Sequential the storage elements at only discrete instants of time.
• Synchronization is achieved by a timing device called a clock
Circuits
generator, which provides a clock signal having the form of a
periodic train of clock pulses .
Asynchronous • A system whose behavior depends upon the input signals at
any instant of time and the order in which the inputs change
• The storage elements commonly used in asynchronous
Sequential sequential circuits are time-delay devices.
• In gate-type asynchronous systems, the storage elements
Circuits
consist of logic gates whose propagation delay provides the
required storage.
, Synchronous Sequential Circuits
The clock pulses are distributed throughout t
system in such a way that storage elements are affect
only with the arrival of each pulse.
Sequential circuits that use clock pulses to contr
storage elements are called clocked sequential circu
and are the type most frequently encountered
practice.
The storage elements (memory) used in clock
sequential circuits are called flipflops.
A flip-flop is a binary storage device capable
storing one bit of information. In a stable state, t
output of a flip-flop is either 0 or 1.
Propagation delays play an important role
determining the minimum interval between clo
pulses that will allow the circuit to operate correctly.
Synchronous clocked sequential circuit
