Custom switched capacitor filter when phase is known appnote

[juanfhj]

Hi. I want to make a bandpass filter a 100 kHz signal with the condition that the phase of the signal is known. I thought I could do this with a custom switched capacitor filter based on the LMF100, but not configured as a general purpose switched capacitor filter, since the phase would be an input to the filter.

Does that have a name? Do you know of any related application note? Thank you

juanfhj
Grad student
Universidad EAFIT
Colombia

 

[keith1200rs]

I am not sure, and I wouldn't call it a bandpass filter, but what you describe sounds like a synchronous detector. Boxcar integrators, multichannel scalers and lock-in detectors also spring to mind, but it depends on exactly what you aretrying to do. All those techniques are for recovering small signals from noise.

Keith

 

[juanfhj]

Magnetic tracker help (was Re: Custom switched capacitor filter)

It's for a virtual reality magnetic position tracker, like those of polhemus . You can check it out in YouTube - Captura movimiento feria createc 2007 monterrey

I happened to write about it in Circuit Cellar 133 back in 2001. Now I'm trying to revamp it. As you can tell from the video, it has the problem that the user must be "immersed" in the field. I want to have the user external to the field, and to achieve this I need to filter out noise which currently makes this unfeasible.

So I wanted to make a custom filter for the tracker, knowing that the phase of my magnetic fields are known.

For a rough draft see

tracker_draft_2010-10-26

Thanks, Juan