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I have set Tow-Thomas filter to get bandpass output. I want center frequency to be precise as much as possible. If there occurse center frequency shift in the lab, what are possible way to compensate this shift?

Tow Thomas Filter

If we take R2=R3=R=R4 and C1=C2=C,

Q = R1 / R , ω0 = 1/(RC) , H = -R1/R

where Q is quality factor, w0 is center angular frequency and H is center frequency gain.

I thought one possible compensation, to target a higher/lower frequency to get desired center frequency. But this is very cumbersome, since it requires to change at least 3 resistors.

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    \$\begingroup\$ First identify the cause of the frequency shift. Is it dependent on supply voltage, or temperature of some of the components? \$\endgroup\$ – Brian Drummond May 20 '17 at 10:54
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    \$\begingroup\$ Temp and supply will affect GBW which in turn affects f as well as C. Use plastic or NPO caps only unless PTC Ceramic are needed \$\endgroup\$ – Sunnyskyguy EE75 Mar 12 '18 at 13:55
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Your assumptions provide the answer.

If we take R2=R3=R=R4

But, of course, there is no need to do that. Specifically, you can make small changes to R2 to vary the center frequency without making appreciable changes to other characteristics. So, for instance, you might replace R2 with two resistors in series: a fixed R2a and a variable R2b. Setting R2a to 90% of R2, and r2b to 20% of R2 will allow an adjustment range of about +/- 5% around the nominal.

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