IWR6843: Asymmetric behavior of detection

Silvia

Part Number: IWR6843

Hello,

Our customer's sensor has different behavior of detection on its left and right side. (Test by mmwave out of box demo)

The precision of one side seems to be poorer than the other side. And the precision of both sides are worse than TI EVB.

They use IWR6843 and the same antenna design as TI EVB.

How to solve this problem by software? (Not changing CFAR or cfg)

Can calibration help? If yes, how to do software calibration?

Thanks.

over 4 years ago

0 CHETHAN KUMAR Y.B. over 4 years ago

TI__Mastermind 25835 points

Silvia,

Could you please highlight the difference between two boards? There are various factors that could lead to this situation.

Is it possible to quantify the results i.e. out of box demo and compare it with TI EVM results?

You could refer to get high-level guidance on the manufacturing aspect of mmWave design.

https://www.ti.com/lit/an/spracg5/spracg5.pdf

Thanks and regards,

CHETHAN KUMAR Y.B.

0 Silvia over 4 years ago in reply to CHETHAN KUMAR Y.B.

Prodigy 215 points

Hello CHETHAN,

The difference between two boards is that the manufacturer is different.

The design remains the same.

Thanks.

0 CHETHAN KUMAR Y.B. over 4 years ago in reply to Silvia

TI__Mastermind 25835 points

Silvia,

If the only difference is the FAB then, Fab related changes need to be analyzed. Below are some pointer to check:

Which TI EVM design is used for the fabrication?

Material choice is also important, In the stack-up we specify the material type.

While Ordering material for example R04835 material, it should be "lopro" type. i.e. RO4835lopro otherwise performance degradation is expected. Or RO3003 material, RO3003 Rolled Cu material should be used, If you use Regular Cu/ or Ed Cu then performance degradation could happen.

Please see below FAB notes, For the Antenna and transmission lines etching tolerance is very important, If it's not followed as per below guidelines Antenna performance would be degraded. You could perform PCB antenna Traces and are they meeting the below expectation or not.

Please do verify Antenna dimensions etched are within +/-1mil dimension. This is the acceptance criteria that need to be established with the FAB vendor.

/cfs-file/__key/communityserver-discussions-components-files/1023/Antenna_5F00_dimensions_5F00_IWR_5F00_60GHz.pdfimensions

Also Via position (L1-L2) also should be within +/-1 mil variation.

Below fabrication notes taken from the PCB layout :

Thanks and regards,

CHETHAN KUMAR Y.B.

0 Silvia over 4 years ago in reply to CHETHAN KUMAR Y.B.

Prodigy 215 points

Hello CHETHAN,

Thank you for your reply.

But the mass production is completed, is there any software method to balance the behavior?

Still, we will check these points with the manufacturer.

Thanks.

0 CHETHAN KUMAR Y.B. over 4 years ago in reply to Silvia

TI__Mastermind 25835 points

Hello Silvia,

Antenna Radiation pattern cannot be modified with software. You could compare Antenna radiation pattern with TI EVM Antenna radiation pattern provided in the Antenna database.

https://dev.ti.com/tirex/explore/node?node=ANS49gohN4gX2.NvHAAGGQ__VLyFKFf__LATEST

And you could compare to what extent the deviation is present. Sometimes, it may be possible this deviation may not effect the some of the end application that is being targeted.

Thanks and regards,

CHETHAN KUMAR Y.B.

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IWR6843: Asymmetric behavior of detection