Agp Signal Noise Decoupling Guidelines; Agp Interface Package Lengths - Intel 855GME Design Manual

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Intel 855GME Chipset and Intel
AGP Port Design Guidelines
7.2.4

AGP Signal Noise Decoupling Guidelines

The main focus of these guidelines is to minimize signal integrity problems on the AGP interface
of the Intel chipset GMCH. The following guidelines are not intended to replace thorough system
validation on Intel chipset-based products.
•
A minimum of six 0.01-µF capacitors are required and must be as close as possible to the
GMCH. These should be placed within 70 mils of the outer row of balls on the GMCH for
VDDQ decoupling. Ideally, this should be as close as possible.
•
The designer should evenly distribute placement of decoupling capacitors in the AGP interface
signal field.
•
Intel recommends that the designer use a low-ESL ceramic capacitor, such as with a 0603
body-type X7R dielectric.
•
To add the decoupling capacitors within 70 mils of the GMCH and/or close to the vias, trace
spacing may be reduced as the traces go around each capacitor. The narrowing of space
between traces should be minimal and for as short a distance as possible (1.0 inch max.).
In addition to the minimum decoupling capacitors, the designer should place bypass capacitors at
vias that transition the AGP signal from one reference signal plane to another. One extra 0.01 uF
capacitor per 10 vias is required. The capacitor should be placed as close as possible to the center
of the via field.
7.2.5

AGP Interface Package Lengths

Table 63. AGP Interface Package Lengths (Sheet 1 of 2)
Signal
GAD0
GAD1
GAD2
GAD3
GAD4
GAD5
GAD6
GAD7
GAD8
GAD9
GAD10
GAD11
GAD12
GAD13
GAD14
GAD15
GAD16
GAD17
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82801DB ICH4 Embedded Platform Design Guide
Pin Package
Number Length (mils)
T6 339
T5 362
R5 440
R3 489
R4 415
R6 343
P5 387
P6 409
N5 466
N3 504
N2 568
M5 510
M1 611
M3 520
M2 566
T7 296
L5 440
K6 491
Signal Pin Number
GADSTB_0 P3
GADSTBB_0 P4
GADSTB_1 J3
GADSTBB_1 J2
GSBA_0 E5
GSBA_1 F5
GSBA_2 E3
GSBA_3 E2
GSBA_4 G5
GSBA_5 F4
GSBA_6 G6
GSBA_7 F6
GSBSTB F2
GSBSTBB F3
GPIPEB D5
GCBEB_0 P2
GCBEB_1 L2
GCBEB_2 L4
Package
Length (mils)
475
439
601
675
686
617
738
865
668
688
518
613
799
761
644
553
583
515
Design Guide