AD8114AST Analog Devices Inc, AD8114AST Datasheet - Page 24

• Manufacturer Part Number: AD8114AST
• Description: IC VIDEO CROSSPOINT SWIT 100LQFP
• Manufacturer: Analog Devices Inc

Specifications of AD8114AST

• Rohs Status: RoHS non-compliant
• Function: Video Crosspoint Switch
• Circuit: 1 x 16:16
• Voltage Supply Source: Dual Supply
• Voltage - Supply, Single/dual (±): ±4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 100-LQFP
• Array Configuration: 16x16
• Number Of Arrays: 1
• Screening Level: Industrial
• Pin Count: 100
• Package Type: LQFP
• Power Supply Requirement: Dual
• Lead Free Status / RoHS Status: Not Compliant

AD8114/AD8115
Effect of Impedances on Crosstalk
The input side crosstalk can be influenced by the output
impedance of the sources that drive the inputs. The lower the
impedance of the drive source, the lower the magnitude of the
crosstalk. The dominant crosstalk mechanism on the input side
is capacitive coupling. The high impedance inputs do not have
significant current flow to create magnetically induced
crosstalk. However, significant current can flow through the
input termination 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
where R
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
mechanism has a high-pass nature; it can be minimized by
reducing the coupling capacitance of the input circuits and
lowering the output impedance of the drivers. If the input is
XT
S
is the source resistance, C
=
20
log
10
[
(
R
S
C
M
)
×
s
]
M
is the mutual capacitance
Rev. B | Page 24 of 32
driven from a 75 Ω 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 Ω 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
where Mxy is the mutual inductance of Output X to Output Y,
and R
crosstalk mechanism can be minimized by keeping the mutual
inductance low and increasing R
be kept low by increasing the spacing of the conductors and
minimizing their parallel length.
XT
L
is the load resistance on the measured output. This
=
20
log
10
(
Mxy
×
s
/
R
L
L
)
. The mutual inductance can