CAT-5 Receiver with Adjustable Line Equalization

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 VPEAK pin, which controls the amount of high frequency peaking. VGAIN adjusts the broadband gain from 0 dB to 3 dB, compensating for the resistive cable loss. VOFFSET 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-overCAT-5 applications. For systems where the UTP cable is longer than 100 meters, two AD8128 devices 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.

Applications

* Keyboard-video-mouse (KVM)

* RGB video over unshielded twisted pair (UTP) cable receivers

* Professional video projection and distribution

* Security video

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

* Up to 100 meters at 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) at 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