Implementing robust surge protection while still maintaining VDSL signal performance becomes increasingly difficult as data rates increase. Secondary side Electronic Current Limiter (ECL) protection schemes provide extremely robust driver protection: the ECL device is placed directly in series with the IC and so forms a very effective surge protection barrier, as will be seen from the surge test results of a very cost effective, fully resettable GR1089 compliant solution. But the same series connection raises questions about the possible impact on performance, such as the impact on termination, bandwidth and signal distortion. Correct placement of the ECL device in the circuit is critical to achieving good performance. Analysis of two popular active termination topologies shows that with correct placement, the introduction of a series ECL protection element has negligible impact on system signal integrity.
During this session, you will learn through presentation of analysis how placement of circuit protection devices at critical points in the secondary side of VDSL circuits can impact the normal signal and termination characteristics when using the two main types of active termination topologies. The same analysis will further show where to place ECL devices in series with the output driver in such a way that will provide exceptional protection, but not significantly degrade the performance of the circuit.
Chief Technology Officer