You might think that when you send component video over a Cat-5 or Cat-6 cable of a given length -- say 200-feet, for example -- that all three signals would experience identical propagation delays traveling through the same cable. Not true. There can be a surprisingly large amount of variation of cable lengths even within the same cable assembly, due to how twisted pairs are twisted and how they twist around each other within the cable.

Now Analog Devices Inc. has introduced a triple video delay line IC specifically to compensate for these differences. It's the industry’s lowest-power, triple-skew-compensating video delay line IC for transmitting clear, sharp images long distances over twisted-pair cable for digital signage, KVM (keyboard, video, mouse), video projection and high-definition surveillance applications.

ADI says the AD8120 triple video delay line IC consumes 50 percent less than its closest competitors; while all 3 channels at maximum delay and its 0.8 percent channel-to-channel gain matching delivers the most accurate RGB color video available – seven times better than competing products. The AD8120’s 150 MHz (mega hertz) bandwidth multiplied by its 50 ns (nanosecond) total delay provides a performance benchmark of 7500MHz-ns BWxD (bandwidth x delay benchmark). The BWxD is an industry benchmark that allows designers and manufacturers to accurately compare performance specifications of triple video delay line ICs.

The AD8120 compensates for the skew created by Cat5, Cat6 or Cat7 cables when transmitting analog video over long distance cables. Skew, or arrival time mismatch, between video signals occurs during video transmission in unshielded twisted pair cables due to the different twist rates that are used for each pair. For this reason, some pairs are longer than others, and in long cables, the difference in propagation time between two pairs can be well into the tens of nanoseconds, creating a noticeable degradation in video performance.

To solve this problem, the AD8120 contains three delay paths that provide broadband delays up to 50 ns in 0.8 ns increments using 64 digital control steps or analog control adjustment. The delay technique used in the AD8120 minimizes noise and offset at the outputs making the AD8120 ideal for use in applications that receive high-resolution video over UTP (unshielded twisted pair) cables.

The AD8120 provides individual delay controls for each channel. The delay times are set independently using a standard 4-wire SPI bus or a standard I2C bus, or by applying analog control voltages to the VCR (voltage control red), VCG (voltage control green), and VCB (voltage control blue) pins. Analog control offers a simple solution for systems that do not have digital control available.

The AD8120 is designed for use with ADI’s AD8123 triple UTP equalizer in video over UTP applications, and it can also be used in other applications where similar controllable broadband delays are required.

The AD8120 is priced at $14.75 in 1,000 quantities. For more information, visit: http://www.analog.com/pr/AD8120