Self demodulating amplifier

[gagir]

Trying to filter a <l00Hz modulated signal, I have across serious filter
design.

I looked to PLL's and a lot is telecom.

Any good reading on instrumentation demodulation would be appreciated.

Eric Girard

 

[Bob]

Trying to filter a <l00Hz modulated signal, I have across serious filter
design.

I looked to PLL's and a lot is telecom.

Any good reading on instrumentation demodulation would be appreciated.

Eric Girard

A little more information on what you are trying to do would be helpful:

What kind of modulation is it (e.g. AM, FM, PM)?
What are the carrier and modulation frequencies?
What other signals are present that you want filtered out?
What do need for a result (a measure of the amplitude of the modulating
signal or the signal itself)?

A lockin might be what you mean by a demodulation instrument. Try:

http://www.thinksrs.com/html/applicationnotes.html

http://www.thinksrs.com/html/technote.html

http://www.thinksrs.com/html/sr830.html

Bob

 

[gagir]

For process monitoring I need to filter out photodiode noise of the same
amplitude as the modulated signal.

Since the process is modulated at 0 to 100Hz I want to see if a resonant
filter would demodulate to have phase and amplitude info.

Would switch capacitor filters cause phase jitter?

Or would a lowpass with a high Q would be better?

Readings on that.

Thank you for your links.

Eric Girard

 

[gagir]

Yeah you are right, just try it...
I will be going with a LTC swiched filter an will see.

gagir