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 VPEAK input controls the amount of high frequency peaking and the VGAIN input adjusts the broadband flat gain, which compensates for the flat cable loss. The VFILTER 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/UTPinput, which can be left floating in UTP applications. The VOFFSET pin allows the dc voltage at the output 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.
FEATURES and BENEFITS
- 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 nsec settling time to 1% with 300 meters of UTP cable
- — 7 ns rise/fall times with 2 V step @ 300 meters of UTP cable
- 3 frequency response gain adjustment pins
- — High frequency peaking adjustment (VPEAK)
- — Output lowpass filter cutoff adjustment (VFILTER)
- — Broadband flat gain adjustment (VGAIN)
- Selectable for UTP or coax compensation
- DC output offset adjust (VOFFSET)
- 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
Analog Devices has introduced what it claims is industry’s fastest 300m UTP cable equaliser for analogue video distribution.
“The AD8122 enables transmission of UXGA and 1080p images over Cat-5 cables up to 300m long,” said the firm.
60MHz of equalised bandwidth is provided, with a 16mVrms noise and 70ns settling time to 1% with 300m cables.
Power consumption is 930mW, and there is an integrated adjustable low pass filter.
Applications are expected in KVM (keyboard-video-mouse) switches, digital signage and professional video projection or distribution.
Complementary components include ADI’s AD8120 video delay line and AD8146/7/8 triple differential drivers for analogue video over Cat-5.
For more read: 1080p video over Cat-5 up to 300m long
