Table of Contents
Advertisement
Motherboard Layout and Routing Guidelines
The methodology that Intel recommends is known as "Sensitivity Analysis". In sensitivity analysis,
interconnect parameters are varied to understand how they affect system timing and signal
integrity. Sensitivity analysis can be further broken into two types of analysis, parametric sweeps
and Monte Carlo analysis, which are described below.
Figure 2-13. Pre-layout simulation process
2.4
Placement & Layout
Once the pre-layout simulation is completed, route the board using the solution space resulting
from the sensitivity analysis.
2.5
Post-Layout Simulation
Following layout, extract the traces and run simulations to verify that the layout meets timing and
noise requirements. A small amount of trace "tuning" may be required, but experience at Intel has
shown that sensitivity analysis dramatically reduces the amount of tuning required.
The post layout simulations should take into account the expected variation for all interconnect
parameters. For timing simulations, use a V
processor and Intel
processor edge fingers to other system components use the standard flight time method.
2-14
Interconnect Simulations (Transmission-Line)
1.75v
1.75v
1.25v
1.25v
0.75v
0.75v
0.25v
0.25v
0.00ns
20.00ns
40.00ns
= ALL OTHERS
= ALL OTHERS
0.00ns
= 82440FXPIN 33
= KLAMATH2PIN X3
= KLAMATH2 X3
X =
0.00ns
y = +0.000v
xdelta = 0.000ns
= KLAMATH1PIN X3
X =
0.00ns
y = +0.000v
NET: SLOWDPNM_LS_12_6, DRIVER: KLAMATH1 TRACKING: KLAMATH1 X3
= KLAMATH1 X3
NET: SLOWDPNM_LS_12_6, DRIVER: KLAMATH2 TRACKING: KLAMATH1 X3
Performance as function of Length
(flight time, signal quality, etc.)
D U AL K L A MA TH FL IGHT T IM E
82 44 0FX to KLA MA TH
D U A L K L A M A T H F L IGH T T IME
8 24 40F X to K LA MA TH
MIN FT RIS IN G (fast silic on - fas t boa rd)
5
M A X F T
4.5
1. 2
LP C = 2. 51 inch es
LF X = 1 .5 inche s
4
LR T = 1.5 inc hes
1
R t = 53 .5 ohm s
3.5
M IN F T
3
LP C = 0. 44 inch es
0. 8
LF X = 0 .0 inche s
2.5
LR T = 1.5 inc hes
R t = 53 .5 ohm s
2
0. 6
1.5
0. 4
1
0.5
5. 5
0. 2
4. 75
0
4
0
3. 25
2. 5
L 2
PC a rd #2 to 82 44 0F X
1. 75
Se p ar ati o n D is tan ce (i n )
L 1
1
PC ard #1 to 8 244 0FX Se par atio n D ista nce (i n )
L 1
PC a rd #1 to 82 44 0F X Se pa rati on Di stan c e (i n)
V i ll a t io n s c a u s e d b y
m in im u m f lig h t t i m e
REF
®
440GX AGPset components. Flight times measured from the Pentium II
1.75v
1.75v
1.25v
1.25v
0.75v
0.75v
0.25v
0.25v
20.00ns
40.00ns
0.00ns
20.00ns
40.00ns
= ALL OTHERS
= ALL OTHERS
0.00ns
20.00ns
= ALL OTHERS
= ALL OTHERS
= 82440FXPIN 33
= 82440FXPIN 33
= KLAMATH2PIN X3
= KLAMATH2PIN X3
= KLAMATH2 X3
xdelta = 0.000ns
= KLAMATH2 X3
X =
0.00ns
y = +0.000v
xdelta = 0.000ns
= KLAMATH1PIN X3
X =
0.00ns
y = +0.000v
xdelta = 0.000ns
= KLAMATH1PIN X3
= KLAMATH1 X3
NET: SLOWDPNM_LS_12_6, DRIVER: KLAMATH1 TRACKING: KLAMATH1 X3
= KLAMATH1 X3
NET: SLOWDPNM_LS_12_6, DRIVER: KLAMATH2 TRACKING: KLAMATH1 X3
Sensitivity Analyses
Monte Carlo
(pass/fail as function of length)
D U A L K L A M A T H P R O C E S S O R C A R D S O L U T IO N S P A C E
MA X FT RIS ING (s low silicon - slow board)
1 2
MA X F T
LP C = 2 .51 in ches
1 1
LF X = 1.5 inc hes
LR T = 1.5 inches
R t = 5 8.5 ohm s
1 0
MI N F T
9
LP C = 0 .44 in ches
LF X = 0.0 inc hes
8
LR T = 1.5 inches
R t = 5 8.5 ohm s
7
6
5
5.5
4.7 5
4
4
3
3.2 5
2.5
L 2
2
PC ard #2 to 8 244 0FX
1.7 5
Se pa ratio n Di sta nce (in )
1
1
0
0
1
2
3
P C a r d t o 82 44 0 F X S e p ar at io n D is t a n c e (in )
Solution Space
D U A L K L A M A T H P R O C E S S O R C A R D S O L U T IO N S P A C E
R t = 5 6
+ /- 5 %
1
M A X F l i g h t T i m e
L P C = 2 . 5 1 in ch e s
1 . 7 5
L F X = 1 .5 i n c h e s
2 . 5
L R T = 1 . 5 i n ch e s
3 . 2 5
M IN F l ig h t T i m e
4
L P C = 0 . 4 4 in ch e s
L F X = 0 .0 i n c h e s
L R T = 1 . 5 i n ch e s
4 . 7 5
5 . 5
S o l u t io n s p a c e
6 . 2 5
7
7 . 7 5
8 . 5
9 . 2 5
1 0
1 0 . 7 5
V i ll a t io n s c a u s e d b y
1 1 . 5
m a x i m u m f li g h t t im e
L 2
P C a r d # 2 to 8 2 4 4 0 F X S e p a r a t io n D i s t a n c e ( in )
of 2/3 VTT ± 2% for both the Intel
®
Intel
440GX AGPset Design Guide
40.00ns
= ALL OTHERS
= ALL OTHERS
= 82440FXPIN 33
= KLAMATH2PIN X3
= KLAMATH2 X3
= KLAMATH1PIN X3
= KLAMATH1 X3
M o n t e C a rl o
Pa s s
Pa s s
F a il
F a il
4
5
6
7
8
9
1 0
1 1
1 2
®
®
Pentium
II
Advertisement
Table of Contents
