ECE4450 L19: Single-Pole OTA-C Filters (Analog Circuits for Music Synthesis, Georgia Tech course)

[@baddriddimworkshop]

Hi, i just wanted to say thank you so much for sharing all this work, i dont understand half of it generally but still, all thisnhas been very usefull. when you try to by your self, you usually try to pick bits here and there to create your own inteligible realm of things, well this place has been a great red fruit field ever since i discovered it. So thank you so much sir. (a nice intro to using ota's can be found in Boscorelli's book "the stompbox cookbook" witch has much more inside than the title would suggest btw)

[@Lantertronics]

Thank you four kind words!

[@boogdish]

Regarding the negative feedback being taken after the buffer you asked at 6:30. In addition to the current considerations, doing it this way includes the buffer in the negative feedback loop and so the OTA's output will then adjust for faults in the buffer itself. The downside would be a situation where you're saturating/clipping the buffer and your OTA becomes even more distorted.

[@boogdish]

Also, I watched your lectures 11-12 years ago and it was great then, but these videos are so much easier to follow and watch, thank you for doing this.

[@Gameboygenius]

Good on you, Fred! That ω𝒸 title was well deserved.

[@superpie0000]

keep posting these, they are helping me wrap my head around analog synthesis

[@Lantertronics]

More to come someday!

[@snnwstt]

Nice out of the box thinking. I am not used to music synthe(ty)sis, but I am sitll strongly amaxed by the different point of view. And that, is the vocative, the different point of view. Sorry for the noice that I brought. Your vids are really interesting, to me.

[@duckythescientist]

I'm continuing to really enjoy these lectures. Thanks again!

[@wsc112782]

Thanks so much for sharing this, I've been working with the SSI2140 and really needed this accessible explanation.

[@jimgibson9811]

Much appreciated

[@krishna34674]

6:25 you take it from there and it make things more liner, the sound difference is pretty apparent at high Q settings. Jfet buffers sound different to high impedance input opamps and I've always wondered why.

[@hlw8051]

Best one yet

[@AnalogDude_]

i see OTA Low pass filters where the feedback of the output goes back to the non inverting pin of the OTA combined with the input signal, while OTA Hi-pass filters use the inverting feedback configuration .. as in your video.

[@MasterMindmars]

P E R F E C T

[@MrTiddles666]

Thanks for the video. I am a little confused at your explanation for using superposition to calculate the inverting configuration since Vout is not an independent source. If you assume it is, I end up with V- = (Rsm/Rbig+Rsm)[Vin+Vout] which doesn't help get to the final fc equation. Given that the filter circuits in the other videos all depend on the inverting configuration I think a more thorough explanation would be very helpful. thanks ever so much for these wonderful videos.

[@Lantertronics]

The equation you have is correct; all you need to do is write Vout = -V- (gm /(sC)), solve that for V-, substitute that into the equation you wrote, and then solve for Vout.

[@Lantertronics]

You can use superposition with dependent sources (unlike what most textbooks say), you just have to be very careful. You have to include all the terms that contribute to the controlling variable before solving for it. My colleague Marshall Leach wrote a paper on it: leachlegacy.ece.gatech.edu/papers/superpos.pdf

[@jinjaninjaboy]

Hi guys, can you recommend somewhere to start with his lectures, or is there entry requirements in order to watch all of these?

[@Lantertronics]

Here's the main ECE4450 playlist: kzbin.info/aero/PLOunECWxELQS5bMdWo9VhmZtsCjhjYNcV To replicate the order I cover material at Georgia Tech, watch "Introduction" lecture, and then watch the 5-part "50 Years of Music Synthesis" lecture. Then, you should take a detour and watch everything but the first lecture in my "ECE Design Fundamentals" playlist: kzbin.info/aero/PLOunECWxELQTn3DQYYB4qaEC9KRK5mHNK That will review some basic circuits concepts I use throughout the course. Then you'll be ready to watch the "Voltage Controlled Amplifiers: Operational Transconductance Amps" lecture and the rest of the ECE4450 lectures in order.

[@peternotpeter]

Just a question because I admittedly don't know the answer, is choosing an inverting or non-inverting purely a design preference or does it change the characteristics of the filter?

[@Lantertronics]

I think it often depends on what else the filter is hooked to and what the goals of the designer are. Like if someone wants the entire filter to be non inverting, they'll use an inverting version if some other system they need to use is inherently inverting.