Questions about power bypass capacitors and explanations when using an external DC power source

RE: Questions about power bypass capacitors and explanations when using an external DC power source

ketiljo — Fri, 08 Sep 2023 09:47:16 GMT

[quote user="yk4224"]1) What I would like to ask is... You said not to use a series resistor (small value)... Can you tell me why?[/quote]

There will be increases rippled because of the voltage drop across the resistor.

[quote user="yk4224"]2) If the VDD Bypass is increased to 22uF (Ceramic), will there be a side effect?[/quote]

A large cap is not a problem.

[quote user="yk4224"]3) Is there a good capacitor value to add to the VDD stage to remove power noise (harmonic components, etc.) generated during 2.4Ghz RF operation?[/quote]

The radio has the highest current draw. There's no RF noise on the VDD pin so you only need to handle the power supply ripple.

RE: Questions about power bypass capacitors and explanations when using an external DC power source

SHMoon — Wed, 06 Sep 2023 01:26:41 GMT

hi, Simonr

As you said, I plan to tune the Power Filter while measuring with an instrument.

Add to,

1) What I would like to ask is... You said not to use a series resistor (small value)... Can you tell me why?

2) If the VDD Bypass is increased to 22uF (Ceramic), will there be a side effect?

3) Is there a good capacitor value to add to the VDD stage to remove power noise (harmonic components, etc.) generated during 2.4Ghz RF operation?

RE: Questions about power bypass capacitors and explanations when using an external DC power source

Simonr — Tue, 05 Sep 2023 11:56:41 GMT

You should not use a series resistor for this purpose at least. From your description it's hard to say what the best setup here would be, as it depends on the battery, the capacitors, and the resistors, etc. so we would recommend that you set up a test rig where you can connect this and do some measurements to find the best setup.

Best regards,

Simon