prbs
TRANSCRIPT
GF’s GCOE, JALGAON 1
PRBS Generator Using VHDLPRBS Generator Using VHDL
Presented By,
Divyesh Patel
&
Alpesh Thesiya
2
Pseudo Random Bit Sequence Pseudo Random Bit Sequence (PRBS)(PRBS)
A Pseudorandom bit generator (PRBS) is used to generate a random sequence of 1’s and 0’s
It is a good approach to use a PRBS sequence as a testing driver than a regular pulse wave sequence
GF’s GCOE, JALGAON
3
How to construct a PRBSHow to construct a PRBS
GF’s GCOE, JALGAON
LFSRLFSR
4
A linear feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state. The only linear functions of single bits are xor and inverse-xor; thus it is a shift register whose input bit is driven by the exclusive-or (xor) of some bits of the overall shift register value.
Types Of LFSR:
Galois Type Fibonacci Type
5
Design a 15 bit Pseudo Random Design a 15 bit Pseudo Random Bit Generator / AnalyzerBit Generator / Analyzer
Design a 15bit PRBS serial bit stream at 25MHz
Design a analyzer to check if an error is encountered in the output signal
GF’s GCOE, JALGAON
6
DescriptionDescription
Circuit 1: 15 DFF connect in series, the output of the
13th and 15th DFF will connect to a XOR logic gate and feedback to the 1st DFF
GF’s GCOE, JALGAON
7
DFF SymbolDFF Symbol
GF’s GCOE, JALGAON
8
DFF SchematicDFF Schematic
GF’s GCOE, JALGAON
9
Rise and Fall time delayRise and Fall time delay
Rise time delay tR (0 > 1) tR = 7.27ns Fall time delay tf (1 > 0) tf = 4.99ns
GF’s GCOE, JALGAON
10
15bit PSRB15bit PSRB
GF’s GCOE, JALGAON
11
15bit PSRB schematic15bit PSRB schematic
GF’s GCOE, JALGAON
12
15bit PSRB Simulation15bit PSRB Simulation
GF’s GCOE, JALGAON
13
ApplicationApplication
Data Encryption/Decryption Digital Signal Processing Wireless Communications Built-in Self Test (BIST) Data Integrity Checksums Data Compression Direct Sequence Spread Spectrum Scrambler/Descrambler Optimized Counters
14
ConclusionConclusion
As the PRBS generator using LFSR is easy because of ease of construction from simple electronics circuit, long periods, and very uniformly distributed output. An LFSR is a linear system, leading to fairly easy cryptanalysis.
GF’s GCOE, JALGAON
15
THANK YOUTHANK YOU
GF’s GCOE, JALGAON