Orin S-parameter files unsymmetric (unidirectional connections)

Autonomous Machines Jetson & Embedded Systems Jetson Orin NX
1

The Jetson Orin NX Series and Jetson Orin Nano Series Signal Integrity Simulation Application Note (Ver 1.5, Release date 2023/01/27)
contains several S-parameter files.

We looked into the files for PCIe,
UPHY\sparam\ondie_T234_P3767A03_UPHY2_Lane01.s16p
UPHY\sparam\ondie_T234_P3767A03_UPHY0.s64p
with the Hyperlynx Touchstone Viewer.

According to the frequency responses, in the first file there is transmission on 8 paths:
S(9,1),S(10,2),S(11,3),S(12,4),S(5,13),S(6,14),S(7,15),S(8,16),
but not in the opposite direction
S(1,9),S(2,10),S(3,11),S(4,12),S(13,5),S(14,6),S(15,7),S(16,8).

So it looks like there is only a unidirectional connection on these paths.
Similarly, in the second file above we see unidirectional connections on 32 paths.
Is this the expected result?

Other files
HDMI_DP\ondie_T234_P3767A03_HDMI_DP.s16p
CSI\sparam\ondie_T234_P3767A03_CSI_0_1.s24p
do not show this phenomenon. In them there are 8 resp. 12 bidirectional connections.

Best regards

4

UPHY’s on-die termination model is unidirectional and the valid path is only from on-die to BGA for TX, and from BGA to on-die for RX.

1 Like
6

Hi,
thank you for your answer.
I did not know that some on-die parts are included in the S-parameter file. This is not mentioned in the pdf.

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