Active RC-filter Basics

#221 In this video I continue looking at filters, by exploring how the basic RC filter can be enhanced by using active, amplification, elements. I look at the various limitations that are brought on by the amplification element but also the benefits and some of the special configurations that can be implemented. Active elements will allow the creation of all the types of filter response, but also will allow easy possibilities to tune the filter response.
Filter series:
Ep1 - Intro : • Intro to Filters
Ep2 - Passive RC Filters: • Passive RC Filters
Ep3 - Active RC Filters: • Active RC-filter Basics
Ep4 - More Active RC Filters: • MORE Active RC Filters
Ep5 - Introduction to LC Filters: • Introduction to LC Fil...
Further reading:
www.analog.com/media/en/train...
archive.org/details/donlancas...
www.ti.com/lit/an/sloa024b/sl...
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[@lethmax3132]

I keep coming back to this channel for all my LTSpice tutorials/guides. So detailed and always filled with real world applications. Thank you!

[@BalticLab]

2:51 "Based on how lucky you are [...]" -> Fundamental Theorem of electrical engineering right there! 😀Great video!

[@PetreRodan]

nice timing :)
I just implemented the simplest non-inverting buffer circuit and used a 11MHz bandwidth opamp (OPA140). everything working fine except that I can't use it for any signal above a few hundred kHz apparently due to the 'low' slew rate - my voltage swing is 0-14V at the input and unfortunately quick transitions get attenuated more than I would like. time for a redesign unfortunately. thank you for the great video!

[@remember2023]

Yep, thats the reason why I always calculate all the necessary data such as, slewrate &gain bandwidth product before selecting an opamp :D

[@anuragmahajan5919]

Thanks! I always learn something new from your videos, I didn't know we have rail to rail input Opamps too

[@mr1enrollment]

Fesz: within this discussion of filters,
it would be informative to include phase delay and group delay as a topic.
Otherwise - yet another thumbs up video. thx!

[@jotnarymir1393]

Yep also slew rate will limit frequency range sooner then bwp. Leared that the hard way. So make sure you pick an op amp with slew rate high enough for application. Oh and make sure capacitor are film or cog types to minimize any capacitance changes and thus changes to cuttoff frequency.

[@rubenhidalgocarrillo]

Hello. And welcome back!

[@bob_mosavo]

Thanks, FesZ 👍

[@bingcheng8419]

Good content! Vibrant red shirt though😅

[@mmh1922]

Well done, thank you.

[@SuperHaptics]

Awesome like always

[@andrewmcfarland57]

All my surplus quad package op amps just got a lot more useful. 🙂

[@FesZElectronics]

There is always an interesting project just around the corner

[@Graham_Wideman]

9:02 "Corner frequency of 1.59 kHz." If we didn't pay attention to the preceding algebra, we might look at that odd number and idly wonder where it came from. "Ah, probably there's a factor of pi/2 somewhere..." but wait, that should be 1.57. Hmmm. Well how about cube root of 4 (=1.587, seems legit!). But actually 1.59 comes from 10/(2pi). It's odd that this 1.59 is so close to those other irrelevant possibilities. Those digits even show up quickly in pi: 3.14 159 265 etc... also irrelevant but slightly mysterious! FesZ -- nice video explanations as usual!

[@arijitdey8316]

Really good man i really follow you

[@johnwest7993]

Thank you.

[@phillipneal8194]

Your explanations are great ! Thank you. So, if I need to create a 20 meter pass band filter, how should I do it ? Lt-Spice and then what ? How do I choose good capacitors, resistors and op-amps. Good in terms of quaity and resistance to heat, etc. And what is gain ? Is that just voltage in , which I should be able to control programmatically or via a potentiometer ?

[@dhuwarakesh6608]

I tried a band pass filter with lag lead combination(unity gain phase shifter)and resistive feedback from stage 2 to 1,performance is highly dependent on the tolerance of components,is there any high Q bandpass filter with somewhat relaxed component tolerance

[@originalmianos]

I think at about 16:50, the input impedance of an op amp is very high and the output impedance is very low, not high

[@andymouse]

16:50 is right at the end but the bit I think you mean is 4:10 and he is talking from the filters point of view and is correct can't find another place he talks about ! :)

[@hedleyfurio]

I placed an L ( 10uH ), C ( 10uF ) filter on the output of a small POE switch mode power supply , in the hopes of reducing ripple , BUT in fact it significantly increased the ripple ?? total mystery any tips ?

[@anuragmahajan5919]

What about the resonant frequency of the LC filter, is the ripple frequency near that frequency?

[@hedleyfurio]

@@anuragmahajan5919 Thanks , I will check on the scope

[@rjordans]

Adding some series resistance to the capacitor can help reduce the q of the filter. High quality gives a bigger resonance peak

[@andymouse]

Thats high ish frequency you might need to add some lower capacitance there.

[@erikdenhouter]

Could it be that the way you connect your scope is a problem ? Fesz learned me that for PSU ripple, it is of most importance to keep the ground connection to the scope (to the probe) as short as possible, preferably one centimeter. Use the little spring that comes with a lot of probes.
Look at 6:15 czcams.com/video/vzhEt3t5VXw/video.html