DS25BR100: Testing setup of PE/EQ performance and AC coupling capacitor before input device

Hi,

A capacitor is not required on the input side of the DS25BR100 to work with a generator.  In most cases the generator can be directly connected to the DS25BR100 inputs.

If the oscilloscope inputs are 50 Ohm to GND, I recommend to use AC coupling capacitors.

Jitter can be caused by over or under equalization.  Is there any additional attenuation besides the EVM in your setup?  What are the DS25BR100 settings?

Regards,

Lee

Hi Lee,
Thank you.

DS90CR288-Long Cable with attenuation-DS25BR100-short cable with small attenuation-AC capacitor-Oscilloscope(50ohm)
Oscilloscope is triggered by clock from DA90CR288 with boosted by DS25BR100 in similar transmission line as above.
Data has very large jitter but clock jitter was not so large.
I tried all of setteing of DS25BR100.

Best regards,

Hi

I have some questions about the setup and measurements.

What is the clock frequency?

Post pictures of the clock and data signals before and after the DS25BR100.  You are probably better off to try the DS25BR110 it has more levels of input equalization to try.  Unfortunately, even the maximum datarate is ~ 600 Mbps, the DS25BRxxx products are optimized for datarates between 1.5 - 2.5 Gbps so less equalization gain is available to help.

Regards,

Lee

Hi Lee,

Clock frequency of DS90CR288 is 25-40MHz which means that data rate is 150Mbps-300Mbps.
Do you have another recommending signal conditioning devices for longer transmission?

Best regards,

Hi

I would try to use the DS25BR110, it is the best 2.5Gbps equalization we have.  The optimal datarate is much higher than the CR288 is producing, but it is the best integrated equalizer I have for this application.  Another option is to build a high pass filter (passive CTLE) which is designed to work at ~ 100MHz.

Regards,

Lee

Hi Lee
Thank you.

I also tried DS25BR110 by DS25BR100EVK.
Output amplitude is enough.
Is unacceptable jitter due to transmission line attenuation lager than capability of the davice?

TI don't have another optimized one for lower data rate?

Best regards,

We do not have an equalizer optimized for lower datarates.

What is the attenuation of the cable at the nyquist frequency between the CR288 and DS25BR110?

What is the part number of the cable?

What is the cable length?

What does the waveform look like at the DS25BR110 input?

Thanks and Regards,

Lee

Hi, Lee

Differential insertion of nycquest frequency(140MHz) of our maximum target datarate (280Mbps) is 15dB.

Attached are input waveform and equalied by DS25BR110 in maximum EQ setting in lower datarate in 175Mbps.

Cable is our orignal one which can be used in half of lengh in channel link I.

Best regards,

 

Belows are waveform pictures.

Thank you.

Hi

At 140 MHz the DS25BRxxx equalizer just does not have enough gain for this application.  The peak gain of the DS25BR111 is close to 15 dB, but this gain is achieved at a frequency of ~ 1.6 GHz.

The only other parts which could work at this datarate were originally developed for video applications.  Have a look at the following device.

www.ti.com/.../DS15EA101

Regards,

Lee

Hi Lee,

Thank you for your advice.

Is DS15EA101 operated only both in DC balanced data and above 150Mbps?

I will use it for extending data from Channel Link I.

I want to apply clock line and data may not be guranteed for DC balanced data.

Best regards,

 

Hi Lee,
Thank you for your comment.

In the assuming application I will use shielde twisted pair and signal groud is conneted between driver and receiver.

Do we have any issue or concerning for locating DS25BR110 next to DS25BR120 in the middle of transmission line?
It is for the purpose of boosting more than DS25BR100 put in the same location.

I think that locating DS25BR110 in the just before reciever and DS25BR120 in the just after receiver is assumed usage. I would like to locating signal conditioning device only 1 portion not separated potion.

Best regards,