ANALOG DEVICES AD8122 Service Manual
Triple Differential Receiver with
AD8122
OUT
R
+IN
R
–IN
R
AD8122
OUT
G
+IN
G
–IN
G
OUT
B
+IN
B
–
IN
B
–IN
CMP1
+IN
CMP1
–IN
CMP2
+IN
CMP2
OUT
CMP2
OUT
CMP1
V
PEAK
V
OFFSETVGAIN
GAIN
R
GAIN
G
GAIN
B
V
FILTER
COAX/UTP
Preliminary Technical Data
FEATURES
Compensates cables to 300 meters for wideband video
60 MHz Equalized BW @ 300 meters of UTP Cable
120 MHz Equalized BW @ 150 meters of UTP Cable
Fast time domain performance
70 ns settling time to 1% with 300 meters of UTP cable
7 ns rise/fall times with 2 V step @ 300 meters of UTP cable
Three frequency response gain adjustment pins
High frequency peaking adjustment (V
Output lowpass filter cutoff adjustment (V
Broadband flat gain adjustment (V
Selectable for UTP or coax compensation
DC output offset adjust (V
OFFSET
)
Low output offset voltage: ±4 mV @ G = 1
Compensates both RGB and YPbPr
Two on-chip comparators with hysteresis
Can be used for common-mode sync extraction
Available in 40-lead, 6 mm × 6 mm LFCSP
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 triple, high speed, differential receiver and
equalizer that compensates for the transmission losses of UTP
and coaxial cables up to 300 meters in length. Various gain
stages are summed together to best approximate the inverse
frequency response of the cable. Each channel features a high
impedance differential input that is ideal for interfacing directly
with the cable.
The AD8122 has two control inputs for optimal cable
compensation, one LPF control input, an input to select
between UTP and coax cable, and an output offset adjust input.
The cable compensation inputs are used to compensate for
different cable lengths; the V
Rev. PrC
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rights of third parties that may result from its use. Specifications subject to change without notice. No
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input controls the amount of high
PEAK
GAIN
)
PEAK
)
FI LTE R
)
300m Adjustable Line Equalization
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
frequency peaking and the V
flat gain, which compensates for the flat cable loss. The V
input controls the cutoff frequency of output lowpass filters on
each channel. Selection between UTP and coaxial cable
compensation responses is determined by the binary
COAX/
applications. The V
input, which can be left floating in UTP
UTP
OFFSET
to be adjusted, which can be useful in dc-coupled systems.
For added flexibility, the gains of each channel can be set to x1
or x2 using the associated GAIN control pins.
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113 ©2012 Analog Devices, Inc. All rights reserved.
input adjusts the broadband
GAIN
pin allows the dc voltage at the output
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FILT ER
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