RF demodulation in my audio amplifier

[Eric_Hsu]

recently i designed an 250mW audio amplifier. my customer use it in digital cordless phone.
but my chip have poor RF immunity, when the phone is on, we can hear "buzz" in the speaker.
what can i do on the ic? anynone have experience in improve RF immunity in audio ic design.
btw: the chip i designed is in bipolar process.

 

[flatulent]

There are several things to try.

1. Keep the RF out of the chip. Use shunt capacitiors on the IO pins. Can you reroute the wires inside the phone? Put metal shielding around your chip. Change the location inside the phone.

2. More drastic is to redesign the chip. In your simulations, add the RF signal to each of the IO leads to see where the problem occurs.

 

[focusdeepwarm01]

Hi flatulent,
I think Eric_Hsu would be interested in how to redesign the chip~