BLE test frequency drift failure

[Fiske]

I have purchased a BLE module using nRF51822. I have used Agilent N4010A to test the RF characteristic of the module. For first log of the BLE moudle (300 pcs), all 300pcs modules can pass the BLE RF spec. However, for second log of the BLE module (same model number), the measured freuqncy drift is around 60kHz to 70 kHz that fail the 50kHz BLE limit. For first log of modue. the frequncy drift is less than 20kHz that pass the BLE limit. I have loaded same DTM firmwre to these two log of modules. Please tell me the possible caused of this issue. For example, crystal failure or load cap failure.

[bjorn-spockeli]

Which BLE module are you using?

[Fiske]

It is a custom make module that is only used by my company and our device is the first prodcut to use this module

[bjorn-spockeli]

Ok, but the module is produced by a third-party? Yes, I would check the crystal and the load capacitors.

[Fiske]

Yes, the module is produced by third-party.

[bjorn-spockeli]

It's hard to say whats wrong without seeing the layout, schematic and BOM of the module. My suggestion would be to contact the module manufacturer regarding this issue. Then they'll have to register a support case through our Mypage support system if they cannot find the cause of the frequency drift.

-Bjørn