Datasheet

ManualsBrandsANALOG DEVICES ManualsInterface ICsInterface IC - receivers 0/3 LFCSP 40 WQ

Triple Differential Receiver with

300 Meter Adjustable Line Equalization

Data Sheet

AD8122

Rev. 0

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Tel: 781.329.4700

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FEATURES

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 (V

PEAK

)

Output low-pass filter cutoff adjustment (V

FI LTE R

)

Broadband flat gain adjustment (V

GAIN

)

Selectable for UTP or coaxial compensation

DC output offset adjustment pin (V

OFFSET

)

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

APPLICATIONS

Keyboard-video-mouse (KVM)

Digital signage

RGB video over UTP cables

Professional video projection and distribution

HD video

Security video

FUNCTIONAL BLOCK DIAGRAM

OUT

GAIN

OUT

GAIN

OUT

GAIN

PEAK

FILTER

OFFSET

GAIN

–IN

CMP1

+IN

CMP1

–IN

CMP2

OUT

CMP1

OUT

CMP2

+IN

CMP2

AD8122

COAX/UTP

–IN

+IN

–IN

+IN

–IN

+IN

10780-001

Figure 1.

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 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 V

PEAK

input controls the amount of high frequency

peaking, and the V

GAIN

input adjusts the broadband flat gain to

compensate for the flat cable loss. The V

FILTER

input controls the

cutoff frequency of output low-pass filters on each channel.

The selection of UTP or coaxial cable compensation responses

is determined by the binary COAX/

UTP

input, which can be

left floating in UTP applications. The V

OFFSET

input allows the

dc voltage at the output to be adjusted, which can be useful in

dc-coupled systems.

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.

Summary of content (21 pages)

PAGE 1
FEATURES 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 compe
PAGE 2
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PAGE 3
AD8122 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 On-Chip Comparators .............................................................. 12 Applications ....................................................................................... 1 Input Single-Ended Voltage Range Considerations .............. 12 Functional Block Diagram ..............................................................
PAGE 4
Data Sheet AD8122 SPECIFICATIONS TA = 25°C, VS = ±5 V, Category 5e UTP cable, input VCM = 0 V, VOFFSET = 0 V, VPEAK, VGAIN, and VFILTER are set to the recommended settings shown in Figure 24, unless otherwise noted. For G = 2, RL = 150 Ω and VOUT = 2 V p-p; for G = 1, RL = 1 kΩ and VOUT = 1 V p-p. Table 1.
PAGE 5
AD8122 Parameter COMPARATORS Output Voltage Level Low, VOL Output Voltage Level High, VOH Hysteresis, VHYST Propagation Delay Low to High, tPD, LH High to Low, tPD, HL Rise Time, tRISE Fall Time, tFALL Output Resistance, VOL Output Resistance, VOH DIGITAL CONTROLS COAX/UTP Pin Input Voltage Level Low, VIL Input Voltage Level High, VIH Input Current, Low Input Current, High PD Pin Input Voltage Level Low, VIL Input Voltage Level High, VIH Input Current, Low Input Current, High POWER SUPPLY Operating Voltage
PAGE 6
Data Sheet AD8122 ABSOLUTE MAXIMUM RATINGS Parameter Supply Voltage Power Dissipation Input Voltage (Any Input) Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec) Junction Temperature Rating 11 V See Figure 2 VS− − 0.3 V to VS+ + 0.3 V −65°C to +125°C −40°C to +85°C 300°C 150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device.
PAGE 7
AD8122 Data Sheet PIN CONFIGURATION AND FUNCTION DESCRIPTIONS AD8122 40 39 38 37 36 35 34 33 32 31 NC AGND –INB +INB AGND –ING +ING AGND –INR +INR TOP VIEW (Not to Scale) 30 29 28 27 26 25 24 23 22 21 1 2 COAX/UTP DVS+ PD VFILTER VPEAK VGAIN DGND VOFFSET DVS– VS+ NOTES 1. TO ACHIEVE THE SPECIFIED THERMAL RESISTANCE, THE EXPOSED PAD ON THE UNDERSIDE OF THE PACKAGE MUST BE SOLDERED TO A PAD ON THE PCB SURFACE THAT IS THERMALLY CONNECTED TO A SOLID PLANE WITH A VOLTAGE BETWEEN VS+ AND VS–. 2.
PAGE 8
Data Sheet Pin No. 31 32 33, 36, 39 34 35 37 38 Mnemonic +INR −INR AGND +ING −ING +INB −INB EP AD8122 Description Positive Input, Red Channel. Negative Input, Red Channel. Analog Ground Reference. Positive Input, Green Channel. Negative Input, Green Channel. Positive Input, Blue Channel. Negative Input, Blue Channel. Exposed Pad.
PAGE 9
AD8122 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS 6 12 3 9 0 6 –3 3 GAIN (dB) –6 100m 150m 200m 250m 300m –9 –12 –3 –6 –15 10 100 FREQUENCY (MHz) –12 0.1 10780-004 1 3 9 0 6 GAIN (dB) –3 100m 150m 200m 3 –3 –12 –6 –15 –9 100 FREQUENCY (MHz) Figure 5. Equalized Frequency Response for Various Coaxial Cable Lengths, G=1 100m 150m 200m 0 –9 –12 0.1 10780-005 1 10 100 FREQUENCY (MHz) Figure 8.
PAGE 10
Data Sheet AD8122 10000 140 OUTPUT VOLTAGE NOISE (nV/√Hz) 130 –3dB BANDWIDTH (MHz) 120 110 G=1 100 G=2 90 80 70 60 300m, G = 2 1000 300m, G = 1 100 150m, G = 1 150m, G = 2 180 200 220 240 260 280 300 CABLE LENGTH (m) 10 0.
PAGE 11
AD8122 Data Sheet 20 20 ΔVOUT/ΔVIN, CM ΔVOUT/ΔVIN, CM 0 0 –20 –40 150m 300m –40 150m –60 –60 –80 –80 –100 0.1 1 10 100 –100 0.1 FREQUENCY (MHz) 10 0 0 ΔVOUT/ΔVSUPPLY –10 NEGATIVE, 300m PSR (dB) PSR (dB) 20 10 –20 100 Figure 19. Input Common-Mode Rejection vs. Frequency for 300 m and 150 m Cable Lengths, G = 2 ΔVOUT/ΔVSUPPLY –10 10 FREQUENCY (MHz) Figure 16. Input Common-Mode Rejection vs.
PAGE 12
Data Sheet AD8122 150m 1V/DIV 500mV/DIV 150m 300m 350 300 400 450 TIME (ns) 100 250 200 150 300 350 450 400 TIME (ns) Figure 25. Equalized Pulse Response for 300 m and 150 m Cable Lengths (2 MHz), G = 2 Figure 22. Equalized Pulse Response for 300 m and 150 m Cable Lengths (2 MHz), G = 1 2 1.00 2 50 0 2.0 1.5 0.50 0 VOUT (V) 0.25 VIN – VOUT 0 –0.25 –0.50 –1 VOUT 1 SETTLING ERROR (%) 1 1.0 0.5 2VIN – VOUT 0 0 –0.5 –1.0 –1 –1.5 –0.
PAGE 13
AD8122 Data Sheet THEORY OF OPERATION The AD8122 is a triple, wideband, low noise analog line equalizer that compensates for losses in UTP cables up to 300 meters in length and coaxial cables up to 200 meters in length. The 3-channel architecture is targeted at high resolution RGB applications, but can be used in HD YPbPr applications as well. The transfer function of the AD8122 can be pin selected for UTP or coaxial cable, and the gain of each channel can be set to 1 or 2.
PAGE 14
Data Sheet AD8122 APPLICATIONS INFORMATION BASIC OPERATION COMPARATOR APPLICATIONS The AD8122 is easy to apply because it contains on chip all components needed for cable loss compensation. Figure 30 shows a basic application circuit for common-mode sync pulse extraction that is compatible with the common-mode sync pulse encoding technique used in the AD8134, AD8142, AD8147, and AD8148 triple differential drivers.
PAGE 15
AD8122 Data Sheet SYNC PULSE EXTRACTION USING COMPARATORS Blue VCM = The AD8122 is useful in many systems that transport computer video signals, which typically comprise red, green, and blue video signals, as well as separate horizontal and vertical sync signals (RGBHV). Because the sync signals are separate and not embedded in the color signals, it is advantageous to transmit them using a simple scheme that encodes them on the three common-mode voltages of the RGB signals.
PAGE 16
Data Sheet AD8122 The VPEAK input is the main peaking control and is used to compensate for the low-pass roll-off in the cable response. The VGAIN input controls the broadband flat gain and is used to compensate for the cable loss that is nominally flat. The output of each channel contains an on-chip adjustable lowpass filter to reduce high frequency noise.
PAGE 17
AD8122 Data Sheet When using a single 5 V supply on the driver side, the commonmode voltage at the driver output is typically 2.5 V (in the case of the AD8142 driver, the common-mode voltage at the output is fixed at 1.5 V). The largest received differential video signal is approximately 700 mV p-p, which adds 175 mVPEAK to each singleended side of the differential signal and results in a worst-case peak voltage of 2.675 V or 1.
PAGE 18
Data Sheet AD8122 OUTLINE DIMENSIONS 0.30 0.25 0.18 31 40 30 0.50 BSC 1 TOP VIEW 0.80 0.75 0.70 10 11 20 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF SEATING PLANE 4.85 4.70 SQ 4.55 EXPOSED PAD 21 0.45 0.40 0.35 PIN 1 INDICATOR BOTTOM VIEW 0.25 MIN FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-WJJD-5. 05-06-2011-A PIN 1 INDICATOR 6.10 6.00 SQ 5.90 Figure 32.
PAGE 19
AD8122 Data Sheet NOTES Rev.
PAGE 20
Data Sheet AD8122 NOTES Rev.