AWR2243: Question about 1.0V of customer's board

Hi Chris,

                      I believe you meant LP87524. can you please advice on the point of measurement?

In general, for PMIC its reference design needs to be strictly followed. 

Regards

Abhed

Abhed,

Yes. It is 1.0V output from LP87524. Sorry for typo.

Customer measured the capacitor under AWR2243. On MMWCAS-RF-EVM customer detected C133. 

You can ignore the high noise in lower frequency due to spectrum analyzer itself.

Thanks,

Chris 

Thanks for the confirmation Chris. Can you confirm on the Revision of the TI EVM, as C133 seems to be on 1.8V and not 1.0V.

Also, is the captured snapshot is during chirping?

Abhed,

I checked with customer again and they corrected that they detected on C139. They referred to MMWCAS-RF-EVM revD schematic.

Yes. The detection is during chirping.

Thanks,

Chris

HI Chris,

               Thanks for the update. From reference layout perspective the PMIC EVM and 4Chip EVM cascade EVM should be followed as closely as possible.

The indicated snapshot is indeed noisy and such ripples should not be there. If it is observed then there can be several reasons for it. The filter placement. Is there a high IR loss for the specific power rail. The decaps placement. 

Try to debug it with switching one TX ON at a time and also slightly increasing the decap value. 

Abhed,

Thanks for your reply. Pls find my feedback below.

Abhed Misra said:

The filter placement.

As I mentioned in previous post, customer puts the LC filter close to AWR2243 instead of PMIC output (how TI EVM designed). Does this cause the issue?

Abhed Misra said:

Is there a high IR loss for the specific power rail.

Customer followed the PMIC design on EVM totally.

Abhed Misra said:

The decaps placement

Customer puts them under AWR2243.

Abhed Misra said:

Try to debug it with switching one TX ON at a time and also slightly increasing the decap value. 

Customer has tried to add 220uF capacitor, but no improvement.

Continuing communication on mail.