I have designed two PCBs that one of them mounted on another. The top PCB includes BC127 at the top right corner of it and the bottom PCB includes several audio circuits outputting audio to a headphone. I should mention that the audio circuits are independent of the BC127 (BC127 used for communication purposes). The communication is based on BLE.
Problem: when the module powered on and it starts to advertise I hear a ticking noise on my headphone. When it connects to a supervisor device the noise becomes even worse.
When I bring a copper layer near the antenna, it suppresses the noise. Is there anyone that has similar problem? How can I fix it?