Method for reducing influence of AC coupling capacitor PAD on transmission of high-speed serial signals

A coupling capacitor, high-speed serial technology, applied in the directions of printed circuit components, electrical connection printed components, and electrical connection formation of printed components, can solve problems such as increased loss and sudden change in transmission line impedance, achieve signal stability, and optimize system design. , the effect of reliable transmission

Inactive Publication Date: 2014-08-13
LANGCHAO ELECTRONIC INFORMATION IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the package PAD will still cause a sudden change in the impedance of the transmission line and increase the loss. Therefore, it is necessary to deal with the capacitor PAD when designing the PCBLAYOUT to reduce the impact of the sudden change in impedance and signal loss caused by the capacitor.

Method used

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  • Method for reducing influence of AC coupling capacitor PAD on transmission of high-speed serial signals
  • Method for reducing influence of AC coupling capacitor PAD on transmission of high-speed serial signals
  • Method for reducing influence of AC coupling capacitor PAD on transmission of high-speed serial signals

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Embodiment

[0018] The design content and the advantage of method of the present invention are understood in detail below by embodiment:

[0019] attached figure 1 It is a schematic diagram of the system structure that the bus passes through, as attached figure 1 As shown, in the designed blade server system, both the computing mainboard and the subboard are plugged into the backplane, and the chip of the computing mainboard is connected to the chip on the subboard through the FDR bus designed on the backplane for signal transmission; from sending to To receive a transmission distance of more than ten inches, each reflection loss factor must be strictly controlled. Take the TOP layer transmission line, with 0201 packaged 100nf capacitor in the middle, the transmission line impedance is 100 ohms, and the transmission length is 2000Mil as an example. If there is no processing under the capacitor PAD, the impedance of the transmission line passing through the capacitor will suddenly change...

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Abstract

The invention discloses a method for reducing influence of an AC coupling capacitor PAD on transmission of high-speed serial signals. An AC coupling capacitor additionally arranged on a high-speed serial bus is designed to be in small package so that the line width of a FDR bus passing through the capacitor can approximate the width of the PAD as much as possible to reduce sudden impedance change caused by change from a bonding pad of the capacitor to a transmission line body capacitor structure. Two-layer hollowing-out treatment is carried out on the FDR bus through the bonding pad of the AC coupling capacitor, so that the impedance of the FDR bus at the position of the AC coupling capacitor is kept unchanged, unnecessary reflection is avoided, the loss of a transmission line is reduced, and signal transmission stability is guaranteed.

Description

technical field [0001] The invention relates to the field of electronics, PCBLAYOUT design and simulation, and in particular to a method for reducing the influence of an AC coupling capacitor PAD on high-speed serial signal transmission. Background technique [0002] With the faster and faster signal transmission speed, the new generation of QPI and PCIE3.0 is up to 8Gpbs, and the FDR bus is up to 14Gbps. As a bus technology of current high-speed switches, the FDR bus mostly involves cross-board interconnection systems, and the transmission distance is relatively long. The bus design has high requirements on insertion loss and return loss. The FDR signal quality judgment standard provided by the MELLANOX chip manufacturer is marked before the 7Ghz frequency point, the insertion loss (IL) is greater than or equal to -25.03dB, and the return loss (RL) is less than -10dB. The multi-board interconnection system generally needs to pass through multiple boards such as the main b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H05K1/11H05K3/40
Inventor 王素华
Owner LANGCHAO ELECTRONIC INFORMATION IND CO LTD
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