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參數(shù)資料
| 型號： | AD8116 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Buffered Video Crosspoint Switch(200MHz,視頻正交開關(guān)) |
| 中文描述： | 緩沖視頻交叉點開關(guān)（200MHz的，視頻正交開關(guān)） |
| 文件頁數(shù)： | 15/28頁 |
| 文件大?。?/td> | 642K |
| 代理商： | AD8116 |
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AD8116
–15–
REV. 0
windings that drives a load resistor. For low frequencies, the
magnitude of the crosstalk is given by:
|
XT
| = 20 log
10
(
Mxy
×
s
/
R
L
)
where
Mxy
is the mutual inductance of output x to output y and
R
L
is the load resistance on the measured output. This crosstalk
mechanism can be minimized by keeping the mutual inductance
low and increasing R
L
. The mutual inductance can be kept low
by increasing the spacing of the conductors and minimizing
their parallel length.
One way to increase the load resistance is to buffer the outputs
with a high input impedance buffer as shown in Figure 27. The
AD8079AR is a dual buffer that can be strapped for a gain of +2
(B grade = +2.2). This offsets the halving of the signal when
driving a standard back-terminated video cable.
The input of the buffer requires a path for bias current. This can
be provided by a 500 k
to 5 k
resistor to ground. This
resistor also serves the purpose of biasing the outputs of the
crosspoints at zero volts when all the outputs are disabled.
In addition, the load resistor actually lowers the crosstalk
compared to the conditions of the AD8116 outputs driving a
high impedance (greater than 10 k
) or driving a video load
(150
). This is because the electric field crosstalk that domi-
nates in the high impedance case has a phase of –90 degrees,
while the magnetic field crosstalk that dominates in the video
load case has a phase of +90 degrees. With a 500 k
to 5 k
load, the contributions from each of these is roughly equal,
and there is some cancellation of crosstalk due to the phase
differences.
PCB Layout
Extreme care must be exercised to minimize additional crosstalk
generated by the system circuit board(s). The areas that must be
carefully detailed are grounding, shielding, signal routing and
supply bypassing.
The packaging of the AD8116 is designed to help keep the
crosstalk to a minimum. Each input is separated from each
other’s input by an analog ground pin. All of these AGNDs
should be directly connected to the ground plane of the circuit
board. These ground pins provide shielding, low impedance
return paths and physical separation for the inputs. All of these
help to reduce crosstalk.
Each output is separated from its two neighboring outputs by
analog supply pins of either polarity. Each of these analog
supply pins provides power to the output stages of only the two
adjacent outputs. These supply pins provide shielding, physical
separation and low impedance supply for the channel outputs.
Individual bypassing of each of these supply pins with a
0.01
μ
F chip capacitor directly to the ground plane minimizes
high frequency output crosstalk via the mechanism of sharing
common impedances.
Each output also has an on-chip compensation capacitor that
is individually tied to a package pin via the signals called
AGND00 through AGND15. This technique reduces crosstalk
by preventing the currents that flow in these paths from sharing
a common impedance on the IC and in the package pins. These
AGNDxx signals should all be connected directly to the ground
plane.
The input and output signals minimize crosstalk if they are
located between ground planes on layers above and below, and
separated by ground in between. Vias should be located as close
to the IC as possible to carry the inputs and outputs to the inner
layer. The only place the input and output signals surface is at
the input termination resistors and the output series back
termination resistors. These signals should also be separated, to
the extent possible, as soon as they emerge from the IC package.
1
2
+V
S
AD8079AR
3
4
5
–V
S
1k
1k
AD8116
OUTXX
OUTYY
AD8116
OUTZZ
OUTWW
–5V
0.1μF
10μF
+
75
75
75
75
8
0.1μF
10μF
+
+5V
TO OTHER
AD8116 OUTPUTS
G = +2
G = +2
Figure 27. Buffering Wired OR Outputs with the AD8079
Evaluation Board
A four-layer evaluation board for the AD8116 is available. This
board has been carefully laid out and tested to demonstrate the
specified high speed performance of the device. Figure 28 shows
the schematic of the evaluation board. Figure 29 shows the
component side silk-screen. The layouts of the board’s four
layers are given in Figures 30, 31, 32 and 33.
The evaluation board package includes the following:
Fully populated board with BNC-type connectors.
Windows based software for controlling the board from a
PC via the printer port.
Custom cable to connect evaluation board to PC.
Disk containing Gerber files of board layout.
All trademarks are properties of their respective holders.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD8117_07 | 600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
| AD8117ABPZ | 600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
| AD8117-EVAL | 600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
| AD8118 | 600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
| AD8118ABPZ | 600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD8116-EB | 制造商:Analog Devices 功能描述:AD8116 EVALUATION BOARD - Bulk |
| AD8116JST | 制造商:Analog Devices 功能描述:Analog Video Crosspoint 200MHz 16 x 16 128-Pin LQFP 制造商:Rochester Electronics LLC 功能描述:TQFP 16X16 VIDEO CROSSPOINT SWITCH - Bulk 制造商:Analog Devices 功能描述:SWITCH CROSSPOINT 16X16 SMD 8116 |
| AD8116JSTZ | 功能描述:IC VIDEO CROSSPOINT SWIT 128LQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 模擬開關(guān)，多路復(fù)用器，多路分解器 系列:- 其它有關(guān)文件:STG4159 View All Specifications 標(biāo)準(zhǔn)包裝:5,000 系列:- 功能:開關(guān) 電路:1 x SPDT 導(dǎo)通狀態(tài)電阻:300 毫歐 電壓電源:雙電源 電壓 - 電源，單路/雙路(±):±1.65 V ~ 4.8 V 電流 - 電源:50nA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:7-WFBGA，F(xiàn)CBGA 供應(yīng)商設(shè)備封裝:7-覆晶 包裝:帶卷 (TR) |
| AD8117 | 制造商:AD 制造商全稱:Analog Devices 功能描述:600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
| AD8117_07 | 制造商:AD 制造商全稱:Analog Devices 功能描述:600 MHz, 32 】 32 Buffered Analog Crosspoint Switch |
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