DS125DF111: Retimer for FPGA at Optical Network Unit

Hi,

Do you have any information or measurements on the electrical signal that the DS125DF111 would receive?  The DS125DF111 CTLE can apply up to 33 dB of boost at 6.25 GHz, but this is targeted at equalizing a PCB channel.

Will signal impairment from an ONU be similar to a PCB channel in that high frequency components of the signal will be attenuated?  Or will an optical signal of -33dBm also have significantly reduced low frequency amplitude?

Thanks,

Drew

Hello Miller,

Electrical signal is a Serdes type, at present , we do not measure it eye diagram with DS125DF111. but it seems signal impairment from an ONU-TIA. We only need DS125  do Signal Enhancement. So, do you have any advice? Or do you have some 1in 2out repeat seders chip recommdation?

Thank you!

Hello Miller,
(1) The attachment is about the schematic diagram and PCB board of the chip application in our company, please help check;
(2) In addition, our application is shown in the following figure (44 pages of the specification);
(3) The rate will be switched between 10.315Gb/s (10GEPON) and 9.95328Gb/s (XGS-PON), whether the chip can be adaptive, if there are no empirical parameters;
(4) In addition, we want to check the eye diagram during the debugging process, can the USB2ANY in the attachment be used?

Thanks,

Sheet1.SchDoc

PCB1.PcbDoc

Hi,

(1) I can provided schematic/layout feeback next week.

(3) Yes, the retimer can be configured to lock to these two data rates.

(4) Yes, you can use the USB2ANY and SigCon Architect to view an eye diagram.

Thanks,

Drew

Hi,

One follow up thought:

The DS125DF111 is known to work well with SFP+ optical modules, where electrical signaling is consistent with SFF-8418 electrical specifications.

As part of the SFF-8418 module receiver specification, there is an eye mask with an eye of at least 0.7UI and 300mVppd.  Do you know how the 10GEPON and XGS-PON electrical signaling will compare?

Thanks,

Drew

Hello Drew,

The 10GEPON and XGS-PON electrical signaling show below.

XGS-PON

10GEPON

Hi,

Thanks for sharing scope data.  Is it correct that this is a single ended signal?  If so, it appears your differential signal amplitude would be around 260mVppd.  

Typically, we target an internal eye of 200mVppd and 0.4UI as recorded by the internal eye monitor of the retimer.  The eye monitor takes eye measurements after the CTLE and DFE stages of the retimer.  This seems to give a small margin to reach the internal eye target for the retimer.  If signal amplitude is the only signal impairment, the retimer CTLE stage can be configured as a limiting amplifier, so this might help with the amplitude.

With this said, is it possible to do testing with one of our DS125DF111EVM?  This could help to better understand retimer performance in this application before designing a board with the retimer.

Thanks,

Drew

Hello Drew,

Thank you for your kindly support. And now we have some questions, We want to DS125MB203  to achieve the following functions: input one optical module signal, output two identical signals , in which the rate of the optical module is 1G, 2.5G (actual 2.488G), 10G (there are two kinds of 10Gepon,one is 10.315G, another 10xgpon is 9.953G);

All of the above rates are required, whether this chip can achieve this function, or you have others for recommenation.

Thanks!