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參數(shù)資料
| 型號(hào)： | AD8111 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Buffered Video Crosspoint Switches(視頻正交開關(guān)) |
| 中文描述： | 緩沖視頻交叉點(diǎn)開關(guān)（視頻正交開關(guān)） |
| 文件頁數(shù)： | 20/28頁 |
| 文件大?。?/td> | 352K |
| 代理商： | AD8111 |
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AD8110/AD8111
–20–
REV. 0
On the output side, the crosstalk can be reduced by driving a
lighter load. Although the AD8110/AD8111 is specified with
excellent differential gain and phase when driving a standard
150
video load, the crosstalk will be higher than the minimum
obtainable due to the high output currents. T hese currents will
induce crosstalk via the mutual inductance of the output pins
and bond wires of the AD8110/AD8111.
From a circuit standpoint, this output crosstalk mechanism
looks like a transformer with a mutual inductance between the
windings that drives a load resistor. For low frequencies, the
magnitude of the crosstalk is given by:
|
X T
| = 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. T his
crosstalk mechanism can be minimized by keeping the mutual
inductance low and increasing R
L
. T he mutual inductance can
be kept low by increasing the spacing of the conductors and
minimizing their parallel length.
PCB Layout
Extreme care must be exercised to minimize additional crosstalk
generated by the system circuit board(s). T he areas that must be
carefully detailed are grounding, shielding, signal routing and
supply bypassing.
T he packaging of the AD8110/AD8111 is designed to help keep
the crosstalk to a minimum. Each input is separated from each
other input by an analog ground pin. All of these AGNDs should
be directly connected to the ground plane of the circuit board.
T hese 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 an
analog ground pin in addition to an analog supply pin of one
polarity or the other. Each of these analog supply pins provides
power to the output stages of only the two nearest outputs.
T hese supply pins and analog grounds provide shielding, physi-
cal separation and a low impedance supply for the outputs.
Individual bypassing of each of these supply pins with a 0.01
μ
F
chip capacitor directly to the ground plane minimizes high fre-
quency output crosstalk via the mechanism of sharing common
impedances.
Each output also has an on-chip compensation capacitor that
is individually tied to the nearby analog ground pins AGND00
through AGND07. T his technique reduces crosstalk by prevent-
ing the currents that flow in these paths from sharing a common
impedance on the IC and in the package pins. T hese AGNDxx
signals should all be directly connected to the ground plane.
T he input and output signals will have minimum 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. T he only place the input and output
signals surface is at the input termination resistors and the out-
put series back termination resistors. T hese signals should also
be separated, to the extent possible, as soon as they emerge from
the IC package.
E valuation Board
A four-layer evaluation board is available for the AD8110/AD8111.
T he exact same board and external components are used for
each device. T he only difference is the device itself, which offers
a selection of a gain of unity or gain of two through the analog
channels. T his board has been carefully laid out and tested to
demonstrate the specified high speed performance of the device.
Figure 44 shows the schematic of the evaluation board. Figure
45 shows the component side silk-screen. T he layouts of the
board’s four layers are given in:
Component Layer—Figure 46
Signal Routing Layer—Figure 47
Power Layer—Figure 48
Bottom Layer—Figure 49
T he 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.
Optimized for video applications, all signal inputs and outputs
are terminated with 75
resistors. Stripline techniques are used
to achieve a characteristic impedance on the signal input and
output lines also of 75
. Figure 50 shows a cross-section of
one of the input or output tracks along with the arrangement of
the PCB layers. It should be noted that unused regions of the
four layers are filled up with ground planes. As a result, the
input and output traces, in addition to having controlled imped-
ances, are well shielded.
All trademarks are properties of their respective holders.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AD8113 | Audio/Video 60 MHz 16 X 16, G = + 2 Crosspoint Switch |
| AD8113JST | Audio/Video 60 MHz 16 X 16, G = + 2 Crosspoint Switch |
| AD8115AST | Low Cost 225 MHz 16 X 16 Crosspoint Switches |
| AD8114-EB | Low Cost 225 MHz 16 X 16 Crosspoint Switches |
| AD8115-EB | Low Cost 225 MHz 16 X 16 Crosspoint Switches |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD8111AST | 制造商:Analog Devices 功能描述:Analog Video Crosspoint 260MHz 16 x 8 80-Pin LQFP 制造商:Analog Devices 功能描述:IC SWITCH CROSSPOINT |
| AD8111ASTZ | 功能描述:IC VIDEO CROSSPOINT SWIT 80LQFP 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) |
| AD8111ASTZ | 制造商:Analog Devices 功能描述:IC SWITCH VIDEO |
| AD8111-EB | 制造商:Analog Devices 功能描述:AD8111 EVAL BOARD 制造商:Analog Devices 功能描述:VID CROSSPT 260MHZ 16X8 - Bulk 制造商:Rochester Electronics LLC 功能描述:AD8111 EVALUATION BOARD - Bulk |
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