BLUENRG-MSQTR chip shuts down randomly in the presence of 1.62 GHz RF

Hi,

We are using the BLUENRG-MSQTR chip in a PCB assembly design that also has a 1.62 GHz transmitter on the board. Our PCB schematic and layout are as least as good as to what is recommended in the application notes. Particular attention was made for co-location of RF transmitters and receivers.

We have a problem.

When transmitting 1.62 GHz RF from a separate transmitter on the board, using an external 32.768 kHz XTAL for the low frequency oscillator on the BLUNRG chip, the chip shuts down randomly and frequently (ie: no BLE RF output, typically after several seconds). We then change to the internal 32.768 kHz oscillator via a register setting, and the chip shuts down much more rarely, but the problem still occurs. We also notice the application of test leads or wires etc exacerbates the symptoms. So the issue is one of RF being coupled into the BLUENRG chip.

The power supply lines seem clean - no disturbances on the DC supply lines.

We can drive 1.6 GHz on a second isolated board and when it is brought physically close to the first board with the BLE chip, the BLE chip stops transmitting. So this is coupled.

Does anyone have a similar experience? Or know of an issue with these chips that causes it to shut down? Any hints?