Analysis and Synthesis of Sequential Circuits using Basic Flip Flops 
Introduction
About the Experiment
This experiment enables a student to learn
- How to realize the functionality of sequential circuits using basic flip-flops
- How to verify the operation of a combinational circuit using flip-flop(D Flip-Flop)
Theory
Sequential Circuits: The logic circuits whose outputs at any instant of time depend not only on the present input but also on the past outputs are called sequential circuits. The simplest kind of sequential circuit which is capable of storing one bit of information is called latch.The operation of basic latch can be modified, by providing an additional control input that determines, when the state of the circuit is to be changed. The latch with additional control input is called the Flip-Flop.The additional control input is either the clock or enable input.
Different types of Flip-Flop: There are four basic types, namely, S-R, J-K, D and T Flip-Flops.
S-R Flip-Flop
Figure 1:Clocked NOR-based S-R Flip-Flop
Figure 2:NAND-based S-R Flip-Flop
Figure 3:Typical wave-form in S-R Flip-Flop
Figure 4:S-R Flip-Flop characteristic Table
NOTE : clk, S and R signals are input signals
Q and Q : Output signals
J-K Flip-Flop
Figure 1:J-K Flip-Flop using S-R Flip-Flop
Figure 2:NAND based J-K Flip-Flop
Figure 3:Typical wave-form in J-K Flip-Flop
Figure 4: J-K Flip-Flop characteristic Table
D Flip-Flop
Figure 1: D Flip-Flop
Figure 2:NAND-based D Flip-Flop
Figure 3:D Flip-Flop characteristic Table
Synthesis using Flip-Flop
As a simple exersise,students can verify the operation of a serial (sequential)adder(1 bit full adder) Carry output of a one bit full adder can be fed back to the input of a D Flip-Flop.The output of this Flip=Flop can be fed back to the carry input of that adder.
Figure 1:Verification of the functionality of a combinational circuit using seqential element(Flip-Flop)
Figure 2:Gate diagram of combinational circuit(1 bit full adder)
Figure 3:Truth table of a 1 bit fulladder