LFSRs are also widely used as event counters and efficient pseudo-random number generators [3]. For example, pseudo-random number generators can be used in cryptography to generate a secret key. Binary counters generally use flip-flops, half adders, and a high-speed carry chain. The LFSR is a shift register that has some of its outputs together in exclusive-OR configurations to form a feedback path. LFSRs are frequently used as pseudorandom pattern generators to generate a random number of 1s and 0s.

1. M.A.AZEEM
14204103
LFSR COUNTER

2. contents
 Introduction
 Block diagram
 Operation
 Applications
 conclusion

3. Introduction
• LFSR is being studied extensively by engineers, designers and design
for testability.
• LFSR is a shift register whose input bit is a linear function of its
previous state.
• Basically the structure is designed by D-flip flops & EXOR gates.
• LFSR’s are mainly operated in two types:
• Ring counter
• Johnson counter
• The maximum-length of an LFSR sequence is 2n -1

4. Block diagram

5. Operation
 LFSR works on the concept of feedback
 Here we use D-registers so as to shift the data by
one unit
 The reset controls that is used for stopping the
ongoing process and set it to ‘0’(initialized)
 The system starts its function when input is high
and reset is made in circuit.
 The EXOR gate will have one input directly and
the other input from the last D-register .
 Thus feedback is given back to the EXOR
gate(input) from the D-register.

6. Applications
 Counters
 Built-in Self-Test (BIST)
 Military applications
 Encryption

7. Conclusion
 LFSRs are more popular because of their compact and simple design
 LFSR counter is best implemented using the pass transistors.

8. THANK Q