How to eliminate or reduce RFI to the sensor output

[madokaaukawa]

Hi all,

Basically, I designed the circuit which using a chemical sensor to detect harmful gas. The circuit is working fine. However, when I use walkie talkie to simulate RFI and test the circuit response, it has big problem. When the walkie talkie is toggled (on/off), the sensor output shoot up quite a bit (like increase 500mV) even worse, and drop down after 2-3 sec. There is no harmful gas actually. I tried many ways to reduce it. like relayout the circuit, copper pour with GND signal. It is not helpful.

Please help

Thanks in advance

 

[godfreyl]

It sounds like you need a low pass filter at the input of your circuit to prevent the RF getting in. Is there any shielding e.g. is it in a metal box?

 

[madokaaukawa]

There is no shielding. The sensor need to be exposed to outside in order to sense harmful gas
So, a low pass filter at the input of the circuit, you mean the input of power? It has decoupling cap

Thank you

 

[etmabreu]

And a low passa filter on the output signal too.