DS125BR820: Insertion loss

Kai Hsiao

Guru 12675 points

Part Number: DS125BR820
Other Parts Discussed in Thread: DS125BR800A

HI Sir

our system structure as below

SOC => 17dB insertion loss => DS125B820 => 23dB insertion loss => PCIE card

May I know

1. Which solution you suggest to use in this loss ? DS125BR820 or DS125BR800A for PCIE gen3 ?

2. How much insertion loss that DS125BR820 and DS125BR800A could recover ?

Thanks

over 6 years ago

0 Lee Sledjeski over 6 years ago

TI__Mastermind 43795 points

Hi Kai,

This level of attenuation in PCIe will come is significant risk. The channel + card will have a total loss of nearly 45 dB. There is a strong likelyhood simply adding an equalizer like the DS125BR820 to this channel will not work.

In most PCIe applications the DS125BR820 device works best. These devices can typicall boost a PCIe channel by ~ 10 dB.

Without any "in channel" equalizers, a typical PCIe Gen3 channel will work out to ~ 22dB loss.

Regards,

Lee

0 Kai Hsiao over 6 years ago in reply to Lee Sledjeski

Guru 12675 points

Hi Lee

What's "in channel " means ?

Do you mean Intel PCIe channel could support 22dB loss without any repeater ? And if use our repeater could support 32dB loss ,is it correct?

Thanks

0 Lee Sledjeski over 6 years ago in reply to Kai Hsiao

TI__Mastermind 43795 points

Hi,

Yes, working with PCIe links or channels with total loss greater than 30-32 dB is very risky. Just a small amount of crosstalk can have a big impact on the system margin.

I recommend to keep channel loss < or = 32 dB for PCIe.

Regards,

Lee

0 Kai Hsiao over 6 years ago in reply to Lee Sledjeski

Guru 12675 points

Hi Lee

Due to our MB have 14dB loss and can't change the PCB

May I know in this condition how much dB loss that DS125BR820 could support ?

SOC => 14dB => DS125BR820 => ? dB loss => Device

Thanks

0 Lee Sledjeski over 6 years ago in reply to Kai Hsiao

TI__Mastermind 43795 points

Hi,

I would recommend to have <32 dB of total attenuation in the channel.

?: <= 18 dB

Regards,

Lee

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DS125BR820: Insertion loss