AWR6843: Requirement for crystal frequency tolerance

Hello Kei,

        Tighter frequency tolerance specs are always better for the mmWave system,  AWR6843/IWR6843 developed and tested with +/50ppm spec limits and later for AWR1843 these specs were relaxed upto +/-200ppm. 

Thanks and regards,

CHETHAN KUMAR Y.B.

Hello, CHETHAN,

Thank you for your answer. I understand.

I have additional questions.

Do you have any ideas what radar characteristics is affected by large freq torelance?

Also, are there any risks to use 200ppm crystal for 6843?

Regards,

Kei

Hello Kei,

     Yes there are adverse effect on large frequency tolerance, There are PLLs and Synthesizes in the mm-Wave sensors, uses these frequency as reference for clocking, If there are large frequency tolerance then there could be issues in the frequency planning within various sub-systems and violation of timing margin could be a possibility.

Also reference frequency for 60GHz-64GHz/76GHz-81GHz are derived from these crystals. If there are frequency deviations then, there could be "out of band emission" from the mmWave sensor could be possible, 

Also there are other peripherals high speed interface such as LVDS clock frequency stability are derived from this, Frequency deviation of this interface would pose challenge w.r.t. to inter operability of other capture interfaces.

And some of the peripheral in the device, which doesn't have source synchronous clocking such as UART, CAN interfaces rely on the tighter clock tolerance specs to interface with external entities. Large frequency deviation causes issues in interfacing with the external peripheral and some time it depends on timing margin available on the receiving devices would limit the number of devices that we could operate with.

Hence always tighter clock timing margins are better for the sensor. 

Thanks and regards,

CHETHAN KUMAR Y.B.

Hello, CHETHAN,

Thank you for your answer. Now I understand adverse effect on large frequency tolerance.
Can I use 200ppm crystal for AWR/IWR6843?
The adverse effect to use 200ppm crystal for AWR/IWR6843 is same as AWR1843?

Regards,
Kei

Hello Kei,

    Thanks for the confirmation, Yes upto 200ppm crystal could be used for AWR/IWR6843. 

Thanks and regards,

CHETHAN KUMAR Y.B.

Hello, CHETHAN,

Thank you, I understand.

Do you have any plans to change the frequency tolerance in the datasheet of IWR/AWR6843 from 50ppm to 200ppm?

Regards,
Kei

CHETHAN,

Thank you for your reply. I understand.

Regards,
Kei