Butterworth Filter Design with Capacitor Multiplier, Op Amp and Transistor
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- Опубликовано: 14 окт 2024
- A Capacitor multiplier is implemented using two operational amplifiers that allow scaling the cap value by a factor K that is controllable by a potentiometer (variable resistor). Then using the scaled capacitor, the rest of the presented circuit implements a 2nd order low pass filter (LPF). With proper choice of value K we can realize a second order Butterworth LPF. The voltage transfer function of the filter and its Bode plot and magnitude frequency response are discussed at the end.
Wow, really interesting capacitor multiplier!
Thank you
Thanks for watching. Glad that you liked the Capacitor Multiplier circuit in this Filter Design video
Hello Prof, I love your videos, they really help me understand OpAmp circuits. The only thing i dont really understand about opamps is that it sometimes feels a bit random how the rule V-=V+ is applied. For example In an Inverting Amplifier V+ is connected to ground, so why isnt V- also virtually shorted to 0V? Why does Vin „dominate“ over ground in this example? Obviously this circuit would be useless if V- was virtually shorted to ground but i don‘t know how you can tell for sure which voltage „dominates“.
I‘d really appreciate if you could explain it to me.
Thanks in advance and have a nice weekend.
Hello, thank you for watching. Glad that electric circuit design videos are helpful. Answering your question, op amp virtual short V-=V+ is practically valid as long as op amp is properly biased and operating stable in linear region of operation. As long as these conditions are satisfied then op amp circuit operates in such a way that tries to reduces the voltage difference between its two input terminals to zero meaning V+=V- . In such scenario, whatever voltage is forced on one input terminal it will be forced at the other input terminal as well as long as op amp is in linear region (not saturated).
I hope this is helpful. Have a great weekend 😎
Adding to my earlier response, here are few more operational amplifier circuit examples to further help with illustrating op amp virtual short and circuit analysis:
ruclips.net/video/Ba-66z4T2FA/видео.html
ruclips.net/video/zPnaCPOUw5E/видео.html
ruclips.net/video/UbeDKaPBlbA/видео.html
@@STEMprof Oh thanks so much that really helped! Only thing i dont fully understand is why the opamp goes to saturation with positive feedback. I know you mentioned it in one of the videos you recommended to me but i got a bit confused. Do you have any video recommendations on saturation specifially?
Thanks in advance and have a nice week.
@@essebrotmitwurst1698 thank you for watching and your interest. See if this example helps: ruclips.net/video/V3bJvlvYcic/видео.html and keep in mind that When op amp in a circuit is in positive feedback, then one input terminal keeps for example rising without the other one catching up. Therefore output of op amp goes to maximum voltage which is close to positive supply voltage.
@@STEMprof the Graph in the Video you recommended is really helpful in understanding how the circuit works! Thank you very much 👍🏻
Thanks for watching. For more Op Amp Circuit and Analog Filter examples please see:
Op Amp Analog Computer Differential Equation Solver ruclips.net/video/ENq39EesfPw/видео.html
Universal Analog Filter Design ruclips.net/video/2J-0msXZE2o/видео.html
How to find Bode Plot, Freq Response, Transfer Function of Analog Filters ruclips.net/video/vZFkPeDa1H8/видео.html
Analog Logarithm Computer ruclips.net/video/RpKEq5WyoLg/видео.html
Laplace Transform Example and S-domain circuit analysis: ruclips.net/video/ps8N5TPM_qU/видео.html
Op Amp circuit Bode Frequency plot ruclips.net/video/BLVzuuqAlZs/видео.html
Lowpass Butterworth Filter: ruclips.net/video/UzCjkwqy-9w/видео.html
Analog Computer to Raise Signal to power n ruclips.net/video/IUTlBH1UraE/видео.html
Triangle Oscillator Op Amp circuit ruclips.net/video/JF5Up_cuL9k/видео.html
Push-Pull Power Amplifier with Darlington Transistors ruclips.net/video/866MYibo8yE/видео.html
Op Amp Analog Computer Differential Equation Solver: ruclips.net/video/ENq39EesfPw/видео.html
Full-Wave Rectifier with Op Amp ruclips.net/video/DJJMNU-CYcg/видео.html.
Differential Equation Solver Analog Circuit ruclips.net/video/R3X5AYNZGEI/видео.html
Complex Sinusoid Oscillator ruclips.net/video/GXRhmwmS5Zk/видео.html
Sawtooth Oscillator Design ruclips.net/video/2eUsGPfqbW4/видео.html
Full-Wave Rectifier circuit example ruclips.net/video/DJJMNU-CYcg/видео.html
ruclips.net/video/5zHXTx-Vl20/видео.html Sawtooth Waveform Generator design with OpAmp, JFET, BJT
ruclips.net/video/HeZRtnRXpEI/видео.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: ruclips.net/p/PLrwXF7N522y4c7c-8KBjrwd7IyaZfWxyt
I hope these Circuit design and analysis videos are helpful. 🙋♂