Triple Differential Receiver with
300 Meter Adjustable Line Equalization
Data Sheet
AD8122
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V
V
V
V
OFFSET GAIN
PEAK
FILTER
Compensates cables up to 300 meters for wideband video
60 MHz equalized BW at 300 meters of UTP cable
120 MHz equalized BW at 150 meters of UTP cable
Fast time domain performance
70 ns settling time to 1% at 300 meters of UTP cable
7 ns rise/fall times with 2 V step at 300 meters of UTP cable
3 frequency response gain adjustment pins
High frequency peaking adjustment (VPEAK
Output low-pass filter cutoff adjustment (VFILTER
Broadband flat gain adjustment (VGAIN
Selectable for UTP or coaxial compensation
DC output offset adjustment pin (VOFFSET
Low output offset voltage: 4 mV at G = 1
Compensates both RGB and YPbPr
2 on-chip comparators with hysteresis can be used
for common-mode sync pulse extraction
Available in 40-lead, 6 mm × 6 mm LFCSP
COAX/UTP
–IN
+IN
R
OUT
R
R
GAIN
R
–IN
G
OUT
G
)
+IN
G
)
GAIN
OUT
G
–IN
+IN
B
)
B
B
GAIN
)
B
–IN
CMP1
OUT
OUT
CMP1
+IN
–IN
CMP1
CMP2
CMP2
+IN
CMP2
AD8122
Figure 1.
APPLICATIONS
Keyboard-video-mouse (KVM)
Digital signage
RGB video over UTP cables
Professional video projection and distribution
HD video
Security video
GENERAL DESCRIPTION
The AD8122 is a high speed, triple differential receiver and
equalizer that compensates for the transmission losses of UTP
cables up to 300 meters in length and coaxial cables up to
200 meters in length. Various gain stages are summed to best
approximate the inverse frequency response of the cable. Each
channel features a high impedance differential input with high
rejection of common-mode (CM) signals that is ideal for inter-
facing directly with the cable.
The selection of UTP or coaxial cable compensation responses
UTP
left floating in UTP applications. The VOFFSET input allows the
dc voltage at the output to be adjusted, which can be useful in
dc-coupled systems.
is determined by the binary COAX/
input, which can be
For added flexibility, the gain of each channel can be set to 1
or 2 using the associated gain control pin.
The AD8122 is available in a 6 mm × 6 mm, 40-lead LFCSP
and is rated to operate over the extended temperature range
of −40°C to +85°C.
The AD8122 has two control inputs for optimal cable
compensation, one LPF control input, an input to select UTP or
coaxial cable, and an input to adjust the dc output offset. The cable
compensation inputs are used to compensate for different cable
lengths: the VPEAK input controls the amount of high frequency
peaking, and the VGAIN input adjusts the broadband flat gain to
compensate for the flat cable loss. The VFILTER input controls the
cutoff frequency of output low-pass filters on each channel.
Rev. 0
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