The DS90UB662-Q1 AEQ can compensate for the transmission channel insertion loss of up to –19.2 dB at 2.1 GHz. When designing the transmission channel, consider the total insertion loss of all components in the signal path between a serializer and a deserializer. Typically, the transmission channel would consist of a serializer PCB, two or more connectors, one or more cables, and a deserializer PCB as shown in Figure 7-4.

Figure 7-4 Typical Transmission Channel Components With Coaxial Cables

Assuming –1.2 dB at 2.1-GHz insertion loss (IL) budget for each serializer and deserializer PCB and 0.1 dB for each connector, it is easy to determine maximum cable reach given the insertion loss characteristic of the cable. For example, Dacar 462 has typical insertion loss of about –1.31 dB/m at 2.1 GHz. With the –19.2-dB total IL budget, the remaining IL budget for the cable is –16.6 dB (–19.2 dB – 2 × (–1.2 dB) – 2 × (–0.1 dB)) after insertion loss of the two PCBs and two connectors are deducted from the total channel IL budget. Given this IL cable budget, the maximum cable reach with a single Dacar 462 is greater than 12 m (–16.6 dB / –1.31 dB/m).

Lower loss cables such as Dacar 302 (typical insertion loss of –0.78 dB/m at 2.1 GHz) may be used alone or in combination with Dacar 462 to achieve even longer transmission distances as exemplified in Figure 7-4. Table 7-4 shows typical Dacar 462 and Dacar 302 cable combinations that achieve a 15-m transmission distance and stay within the maximum insertion loss budget.