High Frequency Design
23-38
ADSP-214xx SHARC Processor Hardware Reference
• To allow better control of impedance and delay, and to reduce
crosstalk, design for lower transmission line impedances.
• Experiment with the board and isolate crosstalk and noise issues
from reflection issues. This can be done by driving a signal wire
from a pulse generator and studying the reflections while other
components and signals are passive.
The capacitors should be placed close to the package as shown in
. The decoupling capacitors should be tied directly to the
power and ground planes with vias that touch their solder pads. Sur-
face-mount capacitors are recommended because of their lower series
inductances (ESL) and higher series resonant frequencies.
Connect the power and ground planes to the processor’s power supply
pins directly with vias, do not use traces. The ground planes should not be
densely perforated with vias or traces as this reduces their effectiveness. In
addition, there should be several large tantalum capacitors on the board.
Designs can use either bypass placement case shown in
, or combinations of the two. Designs should try to
minimize signal feedthroughs that perforate the ground plane.
Figure 23-12. Bypass Capacitor Placement
BYPA
SS
CAPACITOR
S
ON NON-COMPONENT
(BOTTOM)
S
IDE OF BOARD, BENEATH D
S
P PACKAGE
BYPA
SS
CAPACITOR
S
ON COMPONENT
(TOP)
S
IDE OF BOARD, AROUND D
S
P PACKAGE
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Содержание SHARC ADSP-214 Series
Страница 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...