Power Distribution System (PDS) Design!

Allen

Introduction:
0 V! i5 F" q  |' R, T1 c       FPGA designers are faced with a unique task when it comes to designing power distribution
- T+ I9 t- C; L- `systems (PDS). Most other large, dense ICs (such as large microprocessors) come with very
2 j. M9 k; @0 k$ n% ]6 O! Jspecific bypass capacitor requirements. Since these devices are only designed to implement
+ `+ M  ^5 |+ C' rspecific tasks in their hard silicon, their power supply demands are fixed and only fluctuate
$ M2 M, Z5 S! w7 ]" D# O0 ^within a certain range. FPGAs do not share this property. Since FPGAs can implement an
almost infinite number of applications at undetermined frequencies and in multiple clock
: K6 g* y1 f5 }  x/ S0 X; ddomains, it can be very complicated to predict what their transient current demands will be.
Since exact transient current behavior cannot be known for a new FPGA design, the only
! T9 |' A: U# w! x$ T$ r7 E5 r$ \- Wchoice when designing the first version of an FPGA PDS is to go with a conservative worstcase
design.
Transient current demands in digital devices are the cause of ground bounce, the bane of highspeed
digital designs. In low-noise or high-power situations, the power supply decoupling
network must be tailored very closely to these transient current needs, otherwise ground
bounce and power supply noise will exceed the limits of the device. The transient currents in an
FPGA are different from design to design. This application note provides a comprehensive
method for designing a bypassing network to suit the individual needs of a specific FPGA
( S, [. `4 o# t* b7 c2 Z* Edesign.
The first step in this process is to examine the utilization of the FPGA to get a rough idea of its
transient current requirements. Next, a conservative decoupling network is designed to fit these
requirements. The third step is to refine the network through simulation and modification of
5 s# Y4 |3 p+ v( ], E- ncapacitor numbers and values. In the fourth step, the full design is built and in the fifth step it is
# V  ]8 M) X" |( }measured. Measurements are made consisting of oscilloscope and possibly spectrum analyzer
readings of power supply noise. Depending on the measured results, further iterations through
! \, F$ e. S5 ~- r  I- v" mthe part selection and simulation steps could be necessary to optimize the PDS for the specific
; ?8 {' f+ C$ `* N: N, r1 w6 }- oapplication. A sixth optional step is also given for cases where a peRFectly optimized PDS is
. r7 J: w$ r  s6 {0 m& \9 q) l* o. G- rneeded.

forevercgh

LZ摘录的一段已经蛮有吸引了，资料不错，谢谢

Iric071

哥們,還有麼 ,繼續發阿...河合

zdz98

有没有中文的,看英文累啊............不过还是先谢谢楼主了.

weekway

多谢楼主了！在这儿总能找到需要的资料！

ugi929

很经典的东西，收藏了