Datasheet

ManualsBrandsANALOG DEVICES ManualsInterface ICsInterface IC - receivers Ethernet 0/1 LFCSP 8 VD

CAT-5 Receiver with

Adjustable Line Equalization

AD8128

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700 www.analog.com

FEATURES

Tuned to compensate for Category-5 (CAT-5) cable losses

Up to 100 meters @ 120 MHz

2 voltage-controlled frequency response adjustment pins

High frequency peaking adjustment

Broadband gain adjustment

2700 V/μs slew rate

Low output noise

1.5 mV rms integrated noise (1 GHz) @ 100 meters

equalized bandwidth

DC output offset adjust

Low offset voltage error: 7 mV typ

Equalized pass-band ripple ±1 dB to 70 MHz

Input: differential or single ended

Supply current: 24 mA on ±5 V

Small 8-lead 3 mm × 3 mm LFCSP

APPLICATIONS

Keyboard-video-mouse (KVM)

RGB video over unshielded twisted pair (UTP) cable receivers

Professional video projection and distribution

Security video

FUNCTIONAL BLOCK DIAGRAM

OFFSET

GAIN

PEAK

OUT

IN+

IN–

AD8128

05699-001

HPF

LPF

Figure 1.

GENERAL DESCRIPTION

The AD8128 is a high speed, differential receiver/equalizer that

compensates for the transmission losses of unshielded twisted

pair (UTP) CAT-5 cables. Various frequency dependent gain

stages are summed together to best approximate the inverse

frequency response of CAT-5/CAT-5e cable. An equalized

bandwidth of 120 MHz can be achieved for 100 meters of cable.

The AD8128 can be used as a standalone receiver/equalizer or

in conjunction with the AD8143, triple differential receiver, to

provide a complete low cost solution for receiving RGB over

UTP cable in such applications as KVM.

The AD8128 has three control pins for optimal CAT-5/CAT-5e

compensation. The equalized cable length is directly proportional

to the voltage applied to the V

PEAK

pin, which controls the

amount of high frequency peaking. V

GAIN

adjusts the broadband

gain from 0 dB to 3 dB, compensating for the resistive cable

loss. V

OFFSET

allows the output to be shifted by ±2.5 V, adding

flexibility for dc-coupled systems.

Low integrated output noise and offset voltage adjust make the

AD8128 an excellent choice for dc-coupled wideband RGB-

over-CAT-5 applications. For systems where the UTP cable is

longer than 100 meters, two AD8128s can be cascaded to

compensate for up to 200 meters of CAT-5/CAT-5e.

The AD8128 is available in a 3 mm × 3 mm 8-lead LFCSP and

is rated to operate over the extended temperature range of

−40°C to +85°C.

Summary of content (12 pages)

PAGE 1
CAT-5 Receiver with Adjustable Line Equalization AD8128 FUNCTIONAL BLOCK DIAGRAM FEATURES AD8128 HPF VIN+ VOUT HPF VIN– LPF VPEAK VGAIN VOFFSET 05699-001 Tuned to compensate for Category-5 (CAT-5) cable losses Up to 100 meters @ 120 MHz 2 voltage-controlled frequency response adjustment pins High frequency peaking adjustment Broadband gain adjustment 2700 V/μs slew rate Low output noise 1.
PAGE 2
AD8128 TABLE OF CONTENTS Features .............................................................................................. 1 Theory of Operation .........................................................................9 Applications....................................................................................... 1 Input Common-Mode Voltage Range Considerations ............9 Functional Block Diagram .............................................................. 1 Applications................
PAGE 3
AD8128 SPECIFICATIONS TA = 25°C, VS = ±5 V, RL = 150 Ω, Belden Cable, VOFFSET = 0 V, VGAIN and VPEAK set to optimized settings (see Figure 4), unless otherwise noted. Table 1.
PAGE 4
AD8128 ABSOLUTE MAXIMUM RATINGS Table 2. Rating ±5.5 V ±VS −3 V to +VS ±VS −40°C to +85°C −65°C to +125°C 300°C 150°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
PAGE 5
AD8128 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS VIN– 2 VGAIN 3 VPEAK 4 PIN 1 INDICATOR AD8128 TOP VIEW (Not to Scale) 8 VS+ 7 VOFFSET 6 VOUT 5 VS– 05699-002 VIN+ 1 Figure 3. Pin Configuration Table 4. Pin Function Descriptions Pin No.
PAGE 6
AD8128 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VS = ±5 V, RL = 150 Ω, Belden Cable, VOFFSET = 0 V, unless otherwise noted. 1.0 2 VOUT = 2V p-p RL = 150Ω 1 0 0.8 –1 MAGNITUDE (dB) 0.7 VPEAK 0.5 0.4 0.3 –4 –5 –6 –8 0.1 0 –3 –7 VGAIN 0.2 –2 0 10 20 30 40 50 60 70 80 90 –9 –10 0.1 100 VPEAK AND V GAIN SETTINGS ARE CONSISTENT WITH OPTIMIZED SETTINGS IN FIGURE 4 VOUT = 2V p-p RL = 150Ω 1 CABLE LENGTH (M) 05699-012 0.6 05699-003 OPTIMIZED VPEAK AND VGAIN (V) 0.
PAGE 7
1.0 VPEAK AND VGAIN SETTINGS ARE CONSISTENT WITH OPTIMIZED SETTINGS IN FIGURE 4 OUTPUT (V) 0.5 0 –0.5 –1.5 05699-009 –1.0 0 20 40 60 80 100 120 140 160 180 200 1.8 1.6 1.4 1.2 1.0 0.8 0.6 VGAIN SETTINGS ARE CONSISTENT WITH OPTIMIZED SETTINGS IN FIGURE 4 0.4 0.2 0 05699-006 1.5 INTEGRATED VOLTAGE NOISE FROM 100kHz TO 1GHz (mV) AD8128 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 450 500 VPEAK (V) TIME (ns) Figure 13. Integrated Voltage Noise vs. VPEAK Figure 10.
PAGE 8
AD8128 10 POWER SUPPLY REJECTION (dB) 0 VOS = 0V VPEAK = 0V VGAIN = 0V +PSR –10 –20 –PSR –30 –40 –50 –70 0.001 05699-015 –60 0.01 0.1 1 10 1k 100 FREQUENCY (MHz) Figure 16. Power Supply Rejection vs. Frequency TEST CIRCUIT VS+ 1µF VS+ 0.01µF 10µF AD8128 VS+ + VS– 10µF + HPF VIN+ CAT-5 50Ω VOUT HPF 50Ω VIN– VS– VS– VPEAK LPF VGAIN VOFFSET VGAIN VOFFSET 0.01µF 0.01µF 0.01µF Figure 17. Rev. 0 | Page 8 of 12 0.
PAGE 9
AD8128 THEORY OF OPERATION The AD8128 is a high speed, low noise analog line equalizer that compensates for losses in CAT-5/CAT-5e cables up to 100 meters with ±1 dB flatness in the pass band out to 70 MHz (see Figure 8). Two continuously adjustable control voltages alter the frequency response to add flexibility to the system by allowing for the compensation of various cable lengths as well as for variations in the cable itself.
PAGE 10
AD8128 APPLICATIONS KVM APPLICATIONS In KVM applications, cable equalization typically occurs at the root of the KVM network. In a star configuration, a driver is located at each of the end nodes and a receiver/equalizer is located at the single root node. In a daisy-chain configuration, each of the end nodes are connected to one another, and one of them is connected to the root. Similarly, the drivers are placed on the nodes, and the receivers/equalizers are placed at the root.
PAGE 11
AD8128 VS+ VS+ VS+ 1µF 0.01µF 1µF 0.01µF AD8128 VS+ AD8128 VS+ HPF VS– + + HPF VIN+ VIN+ VOUT HPF VIN– VOUT HPF VIN– LPF VGAIN VS– VOFFSET VPEAK LPF VGAIN VS– VOFFSET VPEAK VS– VS– 0.01µF 1µF VOFFSET VGAIN VPEAK 0.01µF 05699-019 1µF Figure 21. Cascaded AD8128 Configuration CASCADED APPLICATIONS To equalize distances longer than the specified 100 meters, the AD8128 can be cascaded to provide equalization for longer distances.
PAGE 12
AD8128 OUTLINE DIMENSIONS 3.00 BSC SQ 0.60 MAX 0.50 0.40 0.30 1 8 PIN 1 INDICATOR 0.90 MAX 0.85 NOM TOP VIEW 0.50 BSC 1.50 REF 5 1.89 1.74 1.59 4 1.60 1.45 1.30 0.70 MAX 0.65 TYP 12° MAX SEATING PLANE 2.75 BSC SQ PIN 1 INDICATOR 0.05 MAX 0.01 NOM 0.30 0.23 0.18 0.20 REF Figure 22.