95-1 under-graduate project
Post on 03-Jan-2016
45 Views
Preview:
DESCRIPTION
TRANSCRIPT
1
95-1 Under-Graduate Project
Adviser: Prof. An-Yeu WuMentor: 詹承洲
第二組溫仁揚 溫昌懌
2
Outline
Purpose of fixed-point Analysis Fixed-point C model Simulation by C language RTL model Conclusion Future work Reference
3
Purpose of Fixed-Point Analysis
Simulate hardware implementation
Quantization Choose the best allocation of
bits
4
Fixed-Point C Model
quantization
saturation
truncation
Work point:
5
Fixed-Point C Model
In every clock :
3 4 5 6 7 8 9
64 point
6
Fixed-Point C Model
Floating point Exactly the value Hard for hardware implementation
Fixed point Quantization Truncation 、 saturation Easy for hardware implementation
7
Fixed-Point C Model
S=1S=1
Take fixed number:
Can reduce ½ of error
error signal caused by the quantization!
The following C model apply the first method
8
Fixed-Point C Model
Requirement: Number of bits for input data: 10~14 Number of bits for output data: 16~20 Dynamic range for input data: [-4 4] Integer part of input data: 3~10 fractional part of input data: 3~10 Twiddle factor: 6~13 SQNR ≥ 50dB
9
Fixed-Point C Model
SQNR: Signal-to-Quantization-Noise Ratio
SNR (S/N) :Signal-to Noise Ratio
10
Fixed-Point C Model
Note that for each bit added to a sample, the SQNR goes up by about 6dB.
xxx.xooo : max error < 0.25xxx.xxoo : max error < 0.125
10log4≈6
½
11
Simulation by C Language(1/9)Wordlength Simulation: fractional=10
Integer=6
68
1012
4 6 8 10-100102030405060
50-60
40-50
30-40
20-30
10-20
0-10
-10-0Twiddle factor word length Integer word length
SQNR:Average of 10 points
12
Simulation by C Language(2/9)
Wordlength Simulation: twiddle factor=13
Integer=6
35
79
35
79
0
10
20
30
40
50
60
50-60
40-50
30-40
20-30
10-20
0-10
SQNR:
Integer wordlengthFractional wordlength
Average of 10 points
13
Simulation by C Language(3/9)
Critical value Take integer wordlength=6
Analyze:
14
Simulation by C Language(4/9)
Wordlength Simulation: integer =6
0
10
20
30
40
50
60
70
80
90
第一季 第三季
東部
中部
北部
6
810
12
3
6
9
0
10
20
30
40
50
60
50-60
40-50
30-40
20-30
10-20
0-10
SQNR:
Twiddle factor wordlengthFractional wordlength
Fractional=10t.f=10
Fractional=9t.f=11
Average of 100 points
15
Simulation by C Language(5/9)
345678910 6
110
10
20
30
40
50
40-50
30-40
20-30
10-20
0-10
Wordlength Simulation: integer =5
T.F wordlengthFrac. wordlength
Average of 100 points
SQNR:
345678910
6
810
12
0
10
20
30
40
50
60
50-60
40-50
30-40
20-30
10-20
0-10
SQNR:
Wordlength Simulation: integer =7
T.F wordlengthFrac. wordlength
16
Simulation by C Language(6/9)Word length Simulation: integer =6
35
79
11
6
9
12
150
0.20.40.6
0.8
1
0.8-1
0.6-0.8
0.4-0.6
0.2-0.4
0-0.2
Twiddle factor wordlengthFractional wordlength
Variance:
Average of 50 points
17
Simulation by C Language(7/9)
With larger wordlength ,there should be smaller variance
But some area are not
Should take more point number
18
Simulation by C Language(8/9)
35
79
1113
6 8 10 12-202468
10 8-10
6-8
4-6
2-4
0-2
-2-0
Wordlength Simulation: integer =6
Twiddle factor wordlength
Difference of SQNR :
Wordlength Simulation: integer =7
35
79
1113
6 8 10 120
2
4
6
8
10
8-106-84-62-40-2
Difference of SQNR :
Fractional wordlengthTwiddle factor wordlength
Fractional wordlength
T.F = 7 T.F = 7
Average of 20 pointsDifference by twiddle factor:
T.F = 10
T.F = 10
19
Simulation by C Language(9/9)
Should be only one maximum
Should take enough point number
20
Conclusion:
Work point: Integer =6 Fractional=10 t.f=10 or Integer =6 Fractional=9 t.f=11
Fractional =7 has the best performance when other variable
21
RTL model
lib.v main.v Connect the lines
22
Lib.v
module BF2ii(Zar,Zai,Zbr,Zbi,Xar,Xai,Xbr,Xbi,s,t);
module BF2i(Zar,Zai,Zbr,Zbi,Xar,Xai,Xbr,Xbi,s);
Already tested successfully.
23
Main.v
Still need to work on it.
24
Future work:
RTL code to be completed Search for better
performance Synthesis circuit
25
Reference ： Shousheng He & Torkelson, M.,”A new approach to pipeline
FFT processor,” Proceedings of IPPS’96, 15-19 April 1996, pp766-770.
施信毓 ,”95-1 Under-Graduate Project, Final Project: Fixed_point”,08 Dec 2006.
http://en.wikipedia.org/ http://zh.wikipedia.org/
top related