Why this design of Sallen-Key Filter is Lowpass? What is the transfer function? What is the best way to explain the lowpass nature of this Sallen Key second order filter intuitively? These questions are addressed in this example.
Thanks for watching. Glad that you liked this filter analysis video. For more analog design examples please see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt
Thank you again for watching. I hope you also like the Full-Wave Rectifier op amp circuit ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html and ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html which is a programmable Differential Equation Solver Analog computer. 🙏
Thanks again for watching. I hope you also enjoy the new amplifier circuit examples: Op Amp Amplifier with Electronic Gain Control ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NoNgQpbj77Y.html How to find Gain of Feedback Amplifier Example with JFET & BJT Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-NB1-mYglXsY.html Op Amp Analog Computer Differential Equation Solver ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Push-Pull Power Amplifier with Darlington Transistors ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-866MYibo8yE.html
You are welcome 🙂. Thanks for watching. Glad that you liked this Analog Sallen-Key Filter analysis video. For more analog design examples please see ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope you enjoy these additional Circuit examples as well. 🙋♂️
You might also like the Sallen-Key Analog Filter Design Tutorial ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KwUnQXbk7gM.html . I hope it is helpful and interesting. Thanks for watching 🙋♂️
An amazing video, but I have a rather silly problem. I didn't really understand why we could use the concept of virtual ground there , where you wrote v+=v-. Because, I have been taught that in case of positive feedback, we can't use virtual ground. Can you explain this? Thanks
My pleasure! Here is a more detailed video Tutorial that might be helpful: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KwUnQXbk7gM.html which is the Sallen-Key Filter Design Tutorial: Low-pass and high-pass Frequency Response, Damping Factor This design works because negative feedback will be far more dominant than the positive feedback in the circuit. Therefore will force Op Amp to operate in linear region where virtual short is valid. For more Analog Filter examples please see: Band-Pass Sallen-Key Filter Design ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lsM09pcrRVE.html Universal Analog Filter Design ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-2J-0msXZE2o.html Butterworth Analog Filter Design with Op Amp ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SIMg5TOIgrA.html Laplace Transform Example and S-domain circuit analysis: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ps8N5TPM_qU.html Op Amp circuit Bode Frequency plot ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-BLVzuuqAlZs.html Bode Plot, Frequency Response, Transfer Function ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vZFkPeDa1H8.html I hope these additional examples are useful as well. 🙂
Thanks for watching. For more Op Amp circuit Examples pls see: Sallen-Key Differential Filter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-bLOn2qcYtyU.html Sallen-Key Analog Filter Design Tutorial ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KwUnQXbk7gM.html Analog Circuit solving Differential Equation ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ENq39EesfPw.html Triangle Oscillator circuit ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JF5Up_cuL9k.html Sallen Key Filter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-yHBsKTAn3VA.html Full-Wave Rectifier ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DJJMNU-CYcg.html Transfer Function of Analog Filter ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-LYARYxwUJgc.html And Diode-Amplifier VTC is analyzed in ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-vpGZkafxMJM.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HeZRtnRXpEI.html presents a circuit with op amps and feedback loops to design an analog computer that solves a second order differential equation. For more analog signal processing examples see: ru-vid.com/group/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt I hope these Circuit engineering and analysis videos are helpful.
Much appreciated Sir 😊 (vx-vin)/r1+(vx-(vo/k))/r2+(vx-vo)/(1/sc2)=0..(1) (vo/k)/(1/sc2)+((vo/k)-vx)/r2=0..(2) Vx=? And then Substitute into the second equation （1）
Thank you so much for this video! I have a doubt, the op-amp circuit I'm trying to solve does not have the R3 to ground but only the (K-1)R3 connected to Vo. Is this configuration familiar to you?
You are very welcome. Glad that video is useful. Yes, as discussed in the following two videos, what you mentioned is a variant of this Sallen-Key design. Please see: Sallen-Key Filter Design Tutorial Video: LPF, HPF Frequency Response and Damping Factor ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KwUnQXbk7gM.html and Band-Pass Sallen-Key Filter Design ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-lsM09pcrRVE.html I hope these additional videos are helpful in answering your question.
@@STEMprof thanks for the reply! i checked the videos you mentioned, however my circuit is not either of them. mine is exactly as the one shown in this video, but without the R3 to ground. it is similar to the LPF shown in ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KwUnQXbk7gM.html but with a resistance connected between negative input terminal and the output. does this make sense? apologies if I am being unclear.
@@phylmath No problem. Yes, I understand. But the resistor connecting output of op amp to negative terminal (without any other connection) does not matter for op amp because practically no current flows to or from input terminal of op amp. So you can short the resistor as if op amp output is connected to input negative terminal similar to my additional op amp videos (links in my earlier message). I hope this helps.
@@STEMprof Understood. So it would then essentially become a simple low pass filter. Thank you very much again. I work on power converters for particle accelerators at CERN and your videos have helped me greatly in understanding and appreciating these purely analog control circuits from the 70s. Hope you keep posting more videos!
@@phylmath Glad that my videos are useful. Please say hello to your colleagues at CERN enabling remarkable particle discoveries. 🙋♂️ Sure, next video will be about Electronic Gain/Attenuation Control that has many applications. I hope you find it useful too. 🙂
Watch minute 8:45 - 10:00 to see the S-domain input-output transfer function of this Salley Key LPF. One can find the DC gain (K) by setting S to zero corresponding to DC or zero frequency. To further help, here are two related filter videos: Sallen-Key Filter Design Tutorial: LPF, HPF Frequency Response, Damping Factor ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KwUnQXbk7gM.html Butterworth Analog Filter Design with Op Amp ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-SIMg5TOIgrA.html
