DS160PR810EVM-RSC: DS160PR810 Gain Setting Challenges

Hi Sandhya,

The configuration seems fine to me. Can you tell us more about the signal you are sending to the redriver from the DSO? Pictures of your output observations would also be helpful if you have those on hand.

Best,

Evan Su

From the DSO, i sent 60MHz with 0dBm amplitude. When i added the gain to redriver (3dB to 18dB), still am getting 0dBm as an output.

Hi Sandhya,

60 MHz is much lower than the frequencies of PCIe signals, so I wonder if the device CTLE would not seriously affect the signal shape or amplitude. Can you explain where you found the 3 dB and 18 dB gain values? The only settings I would expect to change the observed signal amplitude of a low-frequency signal are the Driver VOD (options from 0 to -6 dB) and DC Gain (0 or +3.5 dB).

Best,

Evan Su

Hello Evan,

I tried the same test for 1 GHz also.

In Sigcon Tool using EQ index values, we can add the gain(we can boost the signal gain)for individual channels. 

In the datasheet they have provided gain values for each EQ index value.

Until now, this was my understanding. Correct me if I am wrong.

Thanks
Sandhya

Hi Sandhya,

The gain values in the datasheet tables you shared are the magnitude of the frequency response of the amplifier at certain frequency points (8 GHz is relevant for operation at Gen 4 speeds, 4 GHz is relevant for operation at Gen 3 speeds). They can be interpreted as a rough measure of how much compensation can be provided for the degradation of high-speed signals, but do not reflect the magnitude of the waveform as a whole.

Best,

Evan Su

Hello Evan,
To further address the signal strength improvement for individual channels, could you provide specific recommendations for achieving this goal? Additionally, I would appreciate your insight on whether the setup I provided aligns with the objective of enhancing signal strength. 

Best regards,

Sandhya

Dear customer,

I am following up on this issue. However, the relevant engineer is out of the office and you can expect a response to your thread by Jan 2nd.

Thank you.

Hi Evan,

Could you also provide insights into the cause of this error, if possible?

Regards,
Sandhya

Hi Sandhya,

1). This could be GUI issue where - for some reason - window driver has timed out and cannot talk to the DS320PR810 device.

2). For your measurement, please note the followings:

a). Make sure there is close to 100-ohm termination at TX side of the DS320PR810. This termination allows RX side of the device to enable its termination on your RF source.

b). Please use about -25dbm power at your RF source. This will enable the device to operate in its linear region without compression.

Regards, Nasser

Hello Nasser,

For your information, I am using DS160PR810 device.

I will check the measurements and let you know.

Regards,
Sandhya

Hello Evan,

Do you have any test data report or any device test reports of the evaluation board? We are unable to diagnosis whether the redriver gain is applying or not.

Thanks
Sandhya

Hi Sandhya,

I don't think we have such materials for the DS160PR810. Section 3 of the User's Guide shows a functional test setup, which is the primary purpose of the EVM. Checking electromagnetic characteristics is only a limited backup when debugging. As I have said before, the efficacy of the EVM and the devices on it should be primarily demonstrated through achieving success in a functional environment with a root complex and endpoint, especially one where enough pre-channel or post-channel loss is added such that the root complex and endpoint have trouble linking up properly without the EVM.

Can you tell us again what your overall technical intentions are for this project (add-in-card, motherboard, cable, etc.)? The testing with the EVM should reflect the location and purpose of the redriver.

Best,

Evan Su