TUSB1002A: Issue with receiver jitter tolerance test

Yi Fan Chiang

Part Number: TUSB1002A

Hi,

I have a system that failed receiver jitter tolerance test for USB3.2 gen 2.

It managed to pass Tx compliance tests for USB3.2 gen 2. No issue with USB3.2 gen 1 for Tx compliance and Rx jitter tolerance tests.

The estimated channel losses are shown in figure below. The Tx and Rx EQ were set to 9.0dB and 5.5dB respectively.

Any idea on how to improve the receiver jitter tolerance? I don't have the equipment for USB3 testing and rely on third party lab to help out on the compliance test. Hence, trial and error method is not easy for me.

Thanks.

Regards,

Yi Fan

over 4 years ago

0 Malik Barton57 over 4 years ago

TI__Guru 64326 points

Hi,

I would first verify with the third party that the test setup has been recently calibrated. This is a common source of errors. Next I would decrease your RX (CH2) EQ to 3.6 dB. How much loss can your PCH receiver recover?

0 Yi Fan Chiang over 4 years ago in reply to Malik Barton57

Prodigy 20 points

Yes, the test setup is calibrated within a year. The PCH receiver can accept about 21dB loss currently (the CTLE setting in PCH is configurable).

I'll get the Rx EQ adjusted to 3.6dB and try again.

Thanks.

0 Malik Barton57 over 4 years ago in reply to Yi Fan Chiang

TI__Guru 64326 points

You can also request test host to enable CTLE EQ from the BERT itself to ensure no errors are caused by the TX signal path instead of the RX signal path.

0 Yi Fan Chiang over 4 years ago in reply to Yi Fan Chiang

Prodigy 20 points

Tried to adjust the Rx (CH2) EQ to 3.6dB. The result for long channel is worse than before. Short channel result are better for low frequency Sj but worse for high frequency Sj.

Is there any filtering requirement for the redriver supply? Currently, its power is sourced from a switching regulator instead of LDO.

Thanks.

0 Malik Barton57 over 4 years ago in reply to Yi Fan Chiang

TI__Guru 64326 points

Hi,

Any noise or ripple on Vcc should be less than 100 mV (VPSN). Is the CTLE function of the BERT enabled?

Interface

Interface forum

TUSB1002A: Issue with receiver jitter tolerance test