ALU and Register File

Final Project Proposal


“
ALU and Register File
”
















Name: Vincent Lixiang Bu


Zhoug Jian Zou


Date: 09/11/2006




2


The Objective for the P
roject

Beside the material from the lecture, we hope this Final Project can help us reach

all of
goals as follows:

Firstly, t
o
develop and fu
rther
our

understanding of how rudimentary logic functions are
designed and implemented at the transistor
-
level in complementary metal
-
oxide
semiconductor (CMOS) technology.

Secondly, t
o d
evelop
our

understanding of fabrication processes for very large sc
ale
integrated (VLSI) circuits, and ability to design the physical layout of VLSI circuits.

Thirdly, t
o develop
our

understanding of delay characterization, capacitance
characterization, and transient analysis used to optimize the performance of VLSI circ
uits,
and the concept of standard cell design methodology used to implement VLSI systems.

Fourthly, t
o further
our

understanding of VLSI design through laborator
y experiments
upon
modern
-
day Cadence
system performance
.

Last but not the least; we hope thi
s Final Project can develop our teamwork abilities,
independent research abilities, learning skills and problem solving skills.



The M
otivation

for the P
roject

The aim of this
final
project is to design the schematic and layout for a 32
-
bit
ALU
, and
if po
ssible manufacture our design.
We are particularly focusing on developing more
functions performed in one ALU, which include Addition, Subtraction, Multiplica
tion,
Logic Complement, Shift
,
Less Than,
AND/NAND, NOT, OR/NOR, XOR/N
X
OR etc.
Beside the functio
n development, w
e are interested in optimizing the speed of our ALU
,
and
try to minimize the overall delay.

If we accomplish
those

initial goals, we hope to
analyze some power, area, and scaling trade
-
offs.






3


Block Diagram



Figure 1. ALU Block Diagram


Block description

The
control logic block

uses the ALU opcode and the status flags to generate individual
control/select signals for the different modules.

In the current implementation,
we use the Carry Look Ahead adder with

4 bit group for
Adder.

The carry select algorithm is also combined with CLA adder to reduce
calculation time.


In the
output multiplier and status flag generation

block the operation result and status
flags are selected according to the ALU opcode. The B
YPASS signal can be used to
disable changes in the status flags. If BYPASS is high, STATUS is always the same as
STATUS_IN.


TEMP_
OUT

Selection

A


STATUS

BYPASS

STATUS_IN

OPCODE

STATUS_IN

OPCODE


C Status


C Status


A B


A B


A B


A B


A B


A B


A B


A B

TEMP_IN

Logic Con
trol


AND
/

NAND


NOT



OR /
N
OR


XOR /

NXOR


Comp


Adder


Less
than


Subtr
act

or



Shift


Output Multiplier and Status Flag Generation

A

B

R


4

Floor Plan

with I/O pins


Figure 2. ALU Floor Plan

gnd


NC

Testmux

gnd


S3


S2


S1


S0


testreset


testqbar

Vdd

B0

B1

B2

B3

A0

A1

A2

A3

TEMP_IN



Adder

NOT

AND / NAND

OR / NOR

XOR / NXOR

Complementary



Subtract


Logic Control


Less Than

Test Logic










Output
M
ultiplier



Shifter




ROUTE

NC

NC

vdd



R0

R1

R2

R3

R4

R5

R6

R7

NC

vdd

C0

C1

C2

C3

gnd



testq


testclk


5

Floorplan description

A3
–

A0

Input A

B3
–

B0


Input B

TEMP_IN

Temporary Input, like Carry Input for Addition

R7
–

R0

Output / Result

S3
–

S0 Shift Select

vdd

Supply Voltage

gnd


Circuit Ground

tst


Test Logic

muxtst


Test the working of the Multiplexer

NC


No Connection






Team Management Plan


For our final project, there is a two member group. We split the tasks into individual part
and cooperated part. For individual part, each member trys to finish his task
independently and flexibly according to perso
nal schedule. For cooperated ones, we will
meet and work all together on some available spot.


For th
e project, the detail works
consist of Schematic, Layout and Simulation and Test.
Here we try to do the Schematic and schematic simulation together, and t
hen do the
layout part. Beside above, there are still some paper works and webpage building up.

Below is our detailed team management:


1. Schematic and Simulation




1.1.
Basic Building Blocks of the ALU


(done already by Vincent)




1.2
.

Intermediate Building Blocks of the ALU



1.2.1
.

1
-
Bit Blocks

(done already by
Z
ou)


1.2.2
.

4
-
Bit Blocks






Zou has already finished :
2
-
1 Mux
,
4
-
1 Mux

and
8
-
1 Mux
;




Vincent has already finished:

Inverter Units
,
OR Units
,

AND Units
,




XOR
,
Units
,
ALU

and

B
-
Select
;


Will do
: ALU


(
Zou
)


1.3
.

Large
Circuit

Blocks



Zou has already finished:
Carry Look Ahead (CLA)



Vincent wi
ll do: Shifter


6



Zou will do: Subtract


We will do corporately:
32
-
Bit ALU
,
Look Ahead Unit

2. Layout



2.1
.

Basic Building Blocks of the ALU


(will do by Vincent)



2.2
.

Intermediate Building Blocks of the ALU



2
.2.1
.

1
-
Bit Blocks

(will do by
Z
ou)



2.2.2
.

4
-
Bit Blocks





Zou will do :
2
-
1 Mux
,
4
-
1 Mux

and
8
-
1 Mux
and
ALU



Vincent will do:
Inverter Units
,
OR Units,
AND Units,
XOR Units
,
ALU




and
B
-
Select
;


2.3
.

Large Circuit Blocks

(We will do corporately)

3. Paper work and We
bpage Building up


3.1
.

Project Proposal (done by Vincent)


3.2
.

Other paper works (will do by Zou)


3.
3
.

Webpage Building up (We will do corporately)

4. Verilog Functional Simulations


Zou is doing this part of
work

right now
;

if possibl
e we will turn in the Verilog code
and simulation result attached in this proposal. Otherwise we will post in our future
Project Webpage.




Appendix: Verilog Functional Simulations