How to choose between DAC and AOC

      In data centers, high-performance computers and high-capacity memory and other equipment between the need for high-speed, high-reliability interconnect transmission, the common use of DAC and AOC. DAC and AOC are produced in Moduletek limited , many people are not clear about the difference between the DAC and AOC, sometimes do not know how to choose. Today we will talk about DAC and AOC to help you better understand and choose the right product.
      What is DAC? Direct Attach Cable, or DAC for short, is generally translated as Direct Attach Cable or Direct Attach Copper Cable, and is divided into passive DAC (Passive Copper Cable) and active DAC (Active Copper Cable), which transmits electrical signals in the middle of the DAC, and doesn't involve the conversion of electricity to light or light to electricity. DAC intermediate transmission are electrical signals, does not involve the conversion of electricity to light or light to electricity.
      Passive DAC use shielded high-speed differential copper cables with no chips on the circuit boards at either end, and no signal processing is done during the entire signal transmission process (refer to Figure 1). Passive DAC are the preferred solution for short distance applications and are commonly used in data centers for data transmission between the same cabinet or adjacent cabinets. The most important features of passive DAC are low cost, ultra-low power consumption ( less than 0.1 watts) and high reliability.

Figure 1 Passive Copper Cable Passive DAC

      Active DAC is similar to passive DAC in that it also uses shielded high-speed differential copper cables. However, it is equipped with high-speed electrical signal compensation chips such as pre-emphasis and equalization internally to compensate for the attenuation of electrical signals in the transmission process, which can increase the data transmission distance between devices such as switches with no compensation function (refer to Figure 2). Compared to passive DAC, its biggest feature is that it uses thinner cables and transmits over a longer distance.

Figure 2 Active Copper Cable Active DAC

      What is AOC? Active Optical Cable, abbreviated as AOC, translates to Active Optical Cable. AOC has two modules at both ends and a section of optical fiber in the middle (refer to Figure 3). There are optical transmitters and optical receivers on the circuit boards in the modules at both ends of the AOC. Their function is to convert electrical signals into optical signals at the transmitter end, which are transmitted to the optical fiber, and then convert the optical signals into electrical signals at the receiver end. Since it uses optical signal transmission, it has a longer transmission distance compared to a DAC, although it is more complex in design and processing due to the optoelectronic conversion involved, and the cost and power consumption are higher.

Figure 3 Active Optical Cable AOC

The following table compares various important parameters of DAC and AOC:

Table 1 Parameter Comparison

      Summary: The previous introduction of the differences and links between AOC and DAC, how to choose which product to use for practical applications?
      DAC low cost, low power consumption, but the transmission distance is short, mainly concentrated in the application of 1 meter to 5 meters of the application scenario, the product structure is simple, few parts, high reliability, suitable for the requirements of low-cost low-power short-distance applications.
      AOC transmission distance is far, commonly used length from 1 m to 30 m, but also can be customized more than 300 m AOC products, but high cost, power consumption, suitable for the requirements of the alignment is convenient or transmission distance is farther away from the scene.
      Active DAC situation is generally used in 5-10 meters of application scenarios, due to the cost of copper cable is much higher than the cost of optical cable, and the cost of optical devices in the rapid decline in the 5-10 meters of this distance interval, the price of active DAC products and AOC products compared to no obvious advantage, but active DAC in the use of the use of more bulky and heavy weight leads to transportation costs are also much higher, so the market share relative to the Passive DAC and active fiber optic cable is much less.
      Moduletek Limited can provide a full range of passive cable, active cable, active fiber optic cable products, welcome to buy.
      If you have any questions about the above content, you can contact us by Email : web@moduletek.com