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A method and apparatus to minimize crosstalk between high-speed transmitter links and receiver links without increasing the number of layers

IP.com Disclosure Number: IPCOM000201576D
Publication Date: 2010-Nov-15
Document File: 5 page(s) / 203K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method and apparatus to minimize crosstalk between high-speed TX and RX links without increasing layer count. The method increases the inductive path on the reference plane in order to minimize crosstalk between aggressor links and victim links. This reduces the number of layers needed to minimize crosstalk while maintaining signal integrity and keeping operating costs low.

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Page 01 of 5

A method and apparatus to minimize crosstalk between high -speed transmitter links and receiver links without increasing the number of layers

Crosstalk (x-talk) between high-speed transmitter links and receiver links is a big problem, as it weakens signal integrity and generates noise as data rates increase. To alleviate the problem, one approach is to route transmitter and receiver links on separate layers. As a consequence of adding more layers, however, costs are driven higher. A method to maintain high quality performance with high-speed transmitters while keeping costs down is needed.

As an example of current practice, Figure 1 illustrates an IBM System x* product in which high-speed TX links and RX links are routed on separate layers because of x-talk. It is 16-layer card. As shown in Figure 1, TX links are routed on layer 10 and RX links are on layer 12. Ground reference is on layer 9, 11, and 13 for current return paths. Additional TX links are routed on layer 14. In this manner, alternative layers act to route TX links and RX links and have ground reference between those signal layers because of x-talk. The problem with this method is the increasing layer count, which generates higher costs.

Figure 1: Current high-speed TX and RX links routing practice

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Page 02 of 5

The disclosed solution is a method and apparatus to minimize crosstalk between high-speed transmitter and receiver links. The core idea of this invention is to create an increased inductive path on the reference plane in order to minimize crosstalk between aggressor links and victim links without increasing la...