Output is determined by the current state and the input. The output is fed back to the input to determine the next output.
Clock
Generates a series of pulses at regular intervals. Used to synchronize the operation of digital circuits.
Clock signal
A square wave with a 50% duty cycle. The signal is high for half the period and low for the other half.
Triggering methods
Determines when the output changes according to the clock signal.
Positive edge-triggered
Output changes on the rising edge of the clock signal.
Negative edge-triggered
Output changes on the falling edge of the clock signal.
Level Triggering
Output changes when the clock signal is high (or low).
Characteristics
Characteristic table
A table of memory, current input and output. Similar to a truth table.
Excitation table
A table used to determine the required inputs for a sequential circuit element to transition from its current state to a desired next state. Provides a mapping between the current state, next state, and the necessary inputs. Essential for designing and analyzing sequential circuits.
Latch & Flip-flop
A memory element that can store a bit.
Latch
Level triggered. Independent of a clock. Asynchronous. Can change state while enabled.
Flip-flop
Edge triggered. Dependent on a clock. Synchronous. Can change state only at rising edge of clock.
Types of sequential circuits
Asynchronous
Works without a clock. Built using latches.
Synchronous
Works based on a clock. Built using flip flops.