| Electronics > Projects, Designs, and Technical Stuff |
| OpAmp for high-Q inductor in ultra-narrow band notch filter in controller applic |
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| ricko_uk:
Hi all, I'm trying to filter out a "single" frequency (200 KHz). i.e. a ultra narrow band pass filter. It works quite well using a simple high-Q LC filter but with the inductor and capacitor tolerances it is hard to tune it to that exact frequency and I need it to be very precise. I have a microcontroller on the board so ideally I want to be able to tune it for the highest amplitude. I know that op-amps can replace inductors. So I think I should be able to adjust (through a digital pot) the resistor in the op-amp circuit that simulates/replaces the inductor. Would such solution work? Can I get a very high-Q response by replacing the inductor with a op-amp circuit? If yes, how? Many thanks :) :) |
| awallin:
the notch center frequency might help here... kHz, MHz, GHz ?? |
| dzseki:
Also if you exactly know what you are looking for consider lock-in amplification instead of high-Q filtering. |
| ricko_uk:
Hi Awalling, 200 KHz is the Frequency. Thank you |
| ricko_uk:
Thank you Dzseki, I googled for hours to find a lock-in amplifier IC or schematic but couldn't. Do you have any pointers for a simple solution? As I mentioned in the reply above the carrier freq is 200KHz and I do have the original clock available on the board as sinewave (I can also make it square wave). Many thanks :) |
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