With the rapid development of network, data center has been facing the challenges of high bandwidth, high reliability and low latency, so it is urgent to provide a low-cost and cost-effective solution for high-speed interconnection. In short distance transmission, compared with the combination of optical module and fiber optic jumper, DAC high-speed cable has the advantages of low power consumption, low cost and convenient use, and has been widely used in interconnected data centers.
Advantages of DAC high-speed cables over optical modules
（1）Energy saving and environmental protection: DAC high-speed cable internal material USES copper core, and copper cooling effect is good, more energy saving and environmental protection.
（2）Low power consumption: the power consumption of DAC high-speed cables is low. Generally speaking, the power consumption of optical modules is above 1W, but the power consumption of DAC high-speed cables is generally less than 0.5w.
（3）Low cost: DAC high-speed cable optical device without optical lasers and other electronic components, can effectively save the cost of manufacturing, and copper cable is much cheaper than the price of optical fiber, DAC high-speed cable can effectively save the use of optical fiber when wiring, thus achieving low cost effect.
Details the DAC high-speed cable from the structure
DAC high speed cable is composed of one cable and two optical devices.
The cable adopts silver-plated conductor, insulating core wire of physical foaming polyolefin material and the way of wire pair shielding/total shielding, which is evenly distributed, with high mechanical strength and insulation adhesion, as well as excellent attenuation performance, low delay and anti-interference. The cable structure is mainly divided into four layers:
（1）The first layer, wrapped core wire, mainly by wrapping the two insulating core wire and ground wire together, wrapped with a layer of aluminum foil and a layer of self-adhesive polyester tape;
（2）The second layer is the core cable, which is mainly composed of several winding core wires. Similarly, the outer layer is wrapped with a layer of polyester belt and aluminum foil mylar belt.
（3）The third layer, metal shielding network, refers to the wire woven fabric outside the core wire, used to enhance the wire shielding effect, to obtain better performance;
（4）The fourth layer, the outer sheath is made of polyethylene and other materials.
The optical devices on both ends of the DAC high-speed cable seem to be the same as optical modules, but in fact they are not real optical modules, because they have no optical laser and no electronic components, and can only transmit electrical signals, not optical signals. Because of this, DAC high-speed cables are cheaper than optical modules, and can greatly save cost and power consumption in short-range applications, making it a low-cost and cost-effective communication solution.
In addition, DAC high-speed cable is divided into active DAC high-speed cable and passive DAC high-speed cable, the difference between the two lies in the active DAC high-speed cable with an extra driver chip, at the same time, the active cable does not need power skills to display its characteristics, while the active cable needs to rely on external power to display characteristics. In general, when the transmission distance is more than 5 meters, in order to reduce the problem of signal interference, the most appropriate choice is the active DAC high-speed cable.
