Design and minimization of reversible programmable logic arrays and its realization using pass...

Design and Minimization of Reversible Programmable Logic Arrays and Its Realization using Pass Transistors

Supervised by Dr. Hafiz Md. Hasan BabuProfessor, Dept. of Computer Science and Engineering

University of Dhaka, Dhaka-1000, BangladeshE-mails: hafizbabu@hotmail.com

Presented by Sajib Kumar MitraMS Student, Dept. of Computer Science and Engineering

University of Dhaka, Dhaka-1000, BangladeshE-mails: sajibmitra.csedu@yahoo.com

Purposes

• Define an new Architecture of RPLAs• Minimization of Quantum Cost• Reduction of Critical Path Delay • Reduction of Number of Gates• Garbage Outputs Optimization• Pass Transistor Realization of RPLAs

Overview• Reversible and Quantum Computing• Reversible Programmable Logic Arrays• Proposed Architecture of Reversible PLAs• Delay Calculation of Reversible PLAs• Pass Transistor Realization of MUX Gate• Performance Analysis• Conclusion

Reversible and Quantum Computing

Reversible Computing

• Equal number of input states and output states• Preserves an unique mapping between input and

output vectors for any Reversible circuit• One or more operations can be united called

Reversible Gate• (N x N) Reversible Gate has N number of inputs

and N number of outputs where N= {1, 2, 3, …}

[1] A. K. Biswas, M. M. Hasan, A. R. Chowdhury, and H. M. H. Babu, “Efficient approaches for designing reversible binary coded decimalimplement in a single adders,” Microelectronics Jounrnal, vol. 39, no. 12, pp. 1693–1703, December 2008.

A

BA B

3

2

1

0

1

0

INP

UT

VE

CT

OR

(A

, B)

OU

TP

UT

VE

CT

OR

(A

B

)

OU

TP

UT

VE

CT

OR

(P

, Q)

3

2

1

0

2

1

INP

UT

VE

CT

OR

(A

, B)

FGA

B Q=A B

P=A

0

3

(a) Irreversible EX-OR operation (b) Reversible EX-OR operation

• Limitation • Feedback is strictly restricted • Fan-out must be one always

Fig. 1: Basic difference between Irreversible and Reversible Circuits

Reversible Computing…

F2GA

BC

A

A C

A B

(d) Feynman Double Gate

PGA

BC

AA B

AB C

(b) Peres Gate

FRGA

BC

A

A’C AB

A’B AC

(f) Fredkin Gate

TGA

BC

A

AB C

B

(c) Toffoli Gate

NFTA

BC

AC’ B’CAC’ BC

A B

(e) New Fault Tolerant Gate

FGAA

B A B

(a) Feynman Gate

Fig. 2: Popular Reversible gates

Reversible Computing…

In Quantum Computing, encode information as a series of quantum-mechanical states such as spin directions of electrons or polarization orientations of a photon that might represent as or might represent a superposition of the two values.

Encoded data is represented by qubits rather than bits which can perform certain calculations exponentially faster than conventional computing.

10 q

Quantum Computing

[2]W. N. N. Hung, X. Song, G. Yang, J. Yang, and M. Perkowski, “Quantum logic synthesis by symbolic reachability analysis,” in 41st Conference on (DAC’04), Design Automation Conference, May 2004, pp. 838–841.

Quantum Computation uses matrix multiplication rather than conventional Boolean operations and the information measurement is realized by calculation the state of qubits .

The matrix operations over qubits are simply specifies by using quantum primitives. For example,

›|B A

|A

|B

|A

›(a) Quantum XOR operation (b) Equivalent matrix

for XOR

UCN=

1 0 0 00 1 0 00 0 0 10 0 1 0

››

Fig. 3: Reversible behavior of Quantum matrix operation

Quantum Computing…

Q= |B A

››

|A

|B ›Quantum XOR operation

›P= |AInput Output

A B P Q

0 0 0 0

0 1 0 1

1 0 1 1

1 1 1 0

Input/output

PatternSymbol

00 a

01 b

10 c

11 d

Quantum Computing…

Fig. 4: Working Principle of Unitary Controlled NOT (UCN)

1 0 0 00 1 0 00 0 0 10 0 1 0

abcd

abdc

Reversible Programmable Logic Arrays

Reversible Programmable Logic Arrays

Reversible Programmable Logic Arrays was first proposed by A. R. Chowdhury for multi-outputs function [4]. Reversible PLA consists of following components:

1. Reversible AND Plane and 2. Reversible EX-OR Plane

Fig. 5: Reversible Programmable Logic Arrays

Reversible Programmable Logic Arrays…

The existing design [4] of Reversible Programmable Logic Arrays is shown in Fig. 6.

Fig. 6: Existing design of Reversible PLAs.[4] Ahsan Raja Chowdhury, Rumana Nazmul, Hafiz Md. Hasan Babu: A New Approach to Synthesize Multiple-Output Functions Using Reversible Programmable Logic Array. VLSI Design 2006: 311-316

Reversible Programmable Logic Arrays…

Limitation of Previous Design:

1. Toffoli gate produces huge number of unused outputs which are same as primary inputs.

2. Used Conventional Architecture (Complement and non-complement lines for copying input variables)

3. Requires huge number of Gates

Proposed Architecture of Reversible PLAs

Proposed Architecture of Reversible PLAs

Proposed Design of RPLAs composed of followings: 1. EX-OR plane Optimization by using FG2. Construction of AND plane by using MUX and FG3. Delay Calculation based on Greedy Approach

We have used the following example to represent the Proposed Design of RPLAs.

Proposed Architecture of Reversible PLAs…

Construction of EX-OR plane :1. EX-OR plane is constructed based on the ordering

of the size of Products of functions2. EX-OR plane defines the particular order of all

products which will be followed by AND plane

Fig. 7: Optimized design of Reversible PLAs by using FG.

Proposed Architecture of Reversible PLAs…

Proposed Architecture of Reversible PLAs…

Sorted list of functions is: f4 f2 f1 f3 f5

f1 f2 f3 f4 f5

ab’ X X X

ab’c X X

a’b’c X

bc’ X X

ac X X X

Size of Function 2 2 3 1 3

FunctionsP

rod

uc

ts

Proposed Architecture of Reversible PLAs…

f1 f2 f3 f4 f5

ab’ X X X

ab’c X X

a’b’c X

bc’ X X

ac X X X

Optimization of EX-OR Plane according to sorted list of functions is:

f4 f2 f1 f3 f5

f4

ac

a’b’c

f2

4

f1

4ab’

ab’c

f3

4

4

bc’

4

4

2

f5

Proposed Architecture of Reversible PLAs…

Theorem 1: Minimum number of Feynman gates to realize EX-OR plane is: n + m – TDOT

Where ,n= number of EX-OR

operationsm= number of output

functionsTDOT= total number of cross-points

f4

ac

a’b’c

f2

4

f1

4ab’

ab’c

f3

4

4

bc’

4

4

2

f5

Proposed Architecture of Reversible PLAs…

Construction of AND plane :1.AND plane is constructed based on the ordering of the Products2. MUX and FG gates are used to design AND plane3. Two different patterns of MUX gates have been used in proposed design as follows:

Fig. 14: Reversible MUX gate and two different templates of MUX gate which

are used in proposed design.

Proposed Architecture of Reversible PLAs…

Proposed Architecture of Reversible PLAs…

Fig. 2: Proposed Architecture of Reversible PLAs.Fig. 8: Proposed design of Reversible Programmable Logic

Arrays

Delay Calculation of Reversible PLAs

Delay Calculation of Reversible PLAs…

We divide the calculation into two phases: a. AND Plane Delay andb. EX-OR Plane Delay

Then we have merged both of the delay respect to both planes. In further realization of delay calculation, we consider the following things:

a. Gate (Via) is represented as circle (DOT).b. Delay of any gate is 1 and via (DOT) denotes 0.c. Decimal value shows the delay of circle

Delay Calculation of Reversible PLAs…

Delay Calculation of AND Plane

Delay Calculation of Reversible PLAs…

Fig. 9: Delay Calculation of Reversible AND plane

Delay Calculation of AND Plane

Delay Calculation of Reversible PLAs…

Delay Calculation of Reversible AND plane

ac

a’b’c

5

ab’

ab’c

6

6

bc’

2

2

2

1 6

5

6

a b c

Delay Calculation of AND Plane

Delay Calculation of Reversible PLAs…

Delay Calculation of Reversible AND plane for each Product line, APD (Pi)

APD (P4)= 21

a b c

Start 2

1 2 3

2 3

3 4 5

6

T

L

B

R

T

L

B

R

APD (P1)= 3

APD (P0)= 3

APD (P3)= 5

APD (P2)= 6

Delay Calculation of EX-OR Plane

Delay Calculation of Reversible PLAs…

Fig. 10: Delay Calculation of Reversible EX-OR plane

Pass Transistor Realization of RPLAs

Delay Calculation of EX-OR Plane

Pass Transistor Realization of RPLAs

Fig. 11: Architecture of Pass Transistor and Working Principle

Delay Calculation of EX-OR Plane

Pass Transistor Realization of RPLAs…

Fig. 12: Pass Transistor Realization of Feynman Gate

Delay Calculation of EX-OR Plane

Pass Transistor Realization of RPLAs…

Fig. 13: Pass Transistor Realization of MUX Gate

Performance Analysis

Performance Analysis

Conclusions

We have proposed a regular structure of Reversible Programmable Logic Arrays (RPLAs) based on MUX and Feynman logic and the focus of our design is as follows:

The garbage outputs as operational outputs that reduced the number of AND operations in RPLAs.AND plane based on the ordering of Products gives an excellent throughput of the overall design. The performance of the proposed design over the existing one. The experimental results show that the proposed design outperforms the existing one in terms of numbers of gates, garbages and quantum costs.

Thank you