We use nRF52840 chipset to design a BT module, and it went into pre-production now. But we found the RX sensitivity is not good. We need your help to confirm the RX sensitivity limit. Module HW&FW info is as below:
Chipset version: nRF52840-QIAA C00
SDK: nRF5_SDK_15.3.0
The sensitivity is nRF52840 Spec is as below picture, you can see there is only typical RX sensitivity value, no max value.
Below table are our 97pcs module RX sensitivity data, you can see the min value is close to the typical value in nRF52840 Spec. But there are two questions as below:
1. Some samples max RX sensitivity of high channel in all condition(1M/2M/S8/S2) are more worse than L/M channel, specially the delta of S8 high channel is up to 10dB(see the red box, H is -92 and M is -102).
We swapped new nRF52840 chipset on NG(not good) module which the sensitivity is -92dBm, then the sensitivity is back to -102dBm, it means the worse RX sensitivity followed NG chipset. Can you explain why some chipset high channel RX sensitivity is worse in S8/S2? From our understand, the delta of H/M/L limit should be lower than 1dB.
2. When we use 6-sigma to calculate the CPK=2.0, then we can get the sensitivity limit, you can see the ROW UCL value(blue box in above table). The Max limit is as below:
1M: -86dBm
2M: -86dBm
S8: -75dBm(out of BT SIG limit value -82dBm)
S2: -88dBm
Base on above data, we make a standard for factory production(see ROW Factory Requirement), the detail is as below table. PLS help us to confirm whether nRF52840 chipset can support this standard? If yes, can we improve the factory requirement? For example, the RX sensitivity limit is -86dBm in 1M, can we improve the limit to -88dBm even to -90dBm?
