參數(shù)資料
型號(hào)： AD8115-EB
廠商： Analog Devices, Inc.
英文描述： Low Cost 225 MHz 16 X 16 Crosspoint Switches
中文描述： 低成本的225 MHz 16 × 16交叉點(diǎn)開(kāi)關(guān)
文件頁(yè)數(shù)： 19/26頁(yè)
文件大?。?/td> 363K
代理商： AD8115-EB
AD8114/AD8115
–19–
REV. 0
common method is to measure “all hostile” crosstalk. This term
means that the crosstalk to the selected channel is measured
while all other system channels are driven in parallel. In general,
this will yield the worst crosstalk number, but this is not always
the case due to the vector nature of the crosstalk signal.
Other useful crosstalk measurements are those created by one
nearest neighbor or by the two nearest neighbors on either side.
These crosstalk measurements will generally be higher than
those of more distant channels, so they can serve as a worst case
measure for any other one-channel or two-channel crosstalk
measurements.
Input and Output Crosstalk
The flexible programming capability of the AD8114/AD8115
can be used to diagnose whether crosstalk is occurring more on
the input side or the output side. Some examples are illustrative.
A given input channel (IN07 in the middle for this example) can
be programmed to drive OUT07 (also in the middle). The input
to IN07 is just terminated to ground (via 50
or 75
) and no
signal is applied.
All the other inputs are driven in parallel with the same test
signal (practically provided by a distribution amplifier), with all
other outputs except OUT07 disabled. Since grounded IN07 is
programmed to drive OUT07, no signal should be present. Any
signal that is present can be attributed to the other 15 hostile
input signals, because no other outputs are driven (they are all
disabled). Thus, this method measures the all-hostile input
contribution to crosstalk into IN07. Of course, the method can
be used for other input channels and combinations of hostile
inputs.
For output crosstalk measurement, a single input channel is
driven (IN00 for example) and all outputs other than a given
output (IN07 in the middle) are programmed to connect to
IN00. OUT07 is programmed to connect to IN15 (far away
from IN00), which is terminated to ground. Thus OUT07
should not have a signal present since it is listening to a quiet
input. Any signal measured at the OUT07 can be attributed to
the output crosstalk of the other 16 hostile outputs. Again, this
method can be modified to measure other channels and other
crosspoint matrix combinations.
Effect of Impedances on Crosstalk
The input side crosstalk can be influenced by the output imped-
ance of the sources that drive the inputs. The lower the imped-
ance of the drive source, the lower the magnitude of the crosstalk.
The dominant crosstalk mechanism on the input side is capaci-
tive coupling. The high impedance inputs do not have signifi-
cant current flow to create magnetically induced crosstalk.
However, significant current can flow through the input termi-
nation resistors and the loops that drive them. Thus, the PC
board on the input side can contribute to magnetically coupled
crosstalk.
From a circuit standpoint, the input crosstalk mechanism looks
like a capacitor coupling to a resistive load. For low frequencies
the magnitude of the crosstalk will be given by:
|
XT
| = 20 log
10
[(
R
S
C
M
)
×
s
]
where
R
S
is the source resistance,
C
M
is the mutual capacitance
between the test signal circuit and the selected circuit, and s is
the Laplace transform variable.
From the equation it can be observed that this crosstalk mecha-
nism has a high-pass nature; it can be also minimized by
reducing the coupling capacitance of the input circuits and
lowering the output impedance of the drivers. If the input is
driven from a 75
terminated cable, the input crosstalk can be
reduced by buffering this signal with a low output impedance
buffer.
On the output side, the crosstalk can be reduced by driving a
lighter load. Although the AD8114/AD8115 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. These currents will
induce crosstalk via the mutual inductance of the output pins
and bond wires of the AD8114/AD8115.
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:
|
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.
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 AD8114/AD8115 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.
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 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. These supply pins provide shielding,
physical 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. This 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. These AGNDxx
signals should all be connected directly to the ground plane.
The 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. The only place the input and output
signals surface is at the input termination resistors and the out-
put series back-termination resistors. To the extent possible,
these signals should also be separated as soon as they emerge
from the IC package.
相關(guān)PDF資料
PDF描述
AD8114 ECONOLINE: REC2.2-S_DRW(Z)/H* - 2.2W DIP Package- 1kVDC Isolation- Regulated Output- 4.5-9V, 9-18V, 18-36V, 36-72V Wide Input Range 2 : 1- UL94V-0 Package Material- Continuous Short Circiut Protection- Cost Effective- 100% Burned In- Efficiency to 84%
AD8114AST Low Cost 225 MHz 16 X 16 Crosspoint Switches
AD8115 Low Cost 225 MHz 16 X 16 Crosspoint Switches
AD8115* No RSENSE Current Mode Synchronous Step-Down Switching Regulator; Package: SO; No of Pins: 16; Temperature Range: 0°C to +70°C
AD8116 Buffered Video Crosspoint Switch(200MHz,視頻正交開(kāi)關(guān))
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD8115-EVAL 制造商:Analog Devices 功能描述:EVAL BD LOW COST 225 MHZ 16 16 CROSSPOINT SWITES - Bulk
AD8116 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:200 MHz, 16 x 16 Buffered Video Crosspoint Switch
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(lèi)別:集成電路 (IC) >> 接口 - 模擬開(kāi)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(kāi)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(lèi)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)
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