Questions tagged [active-filter]
An active filter is a type of analog electronic filter that uses active components such as an amplifier.
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LTC 2065 is not working between 2 V - 4 V power supply
I'm having a problem with the LTC2065 operational amplifier design. I use a 3.3V supply as I show in the picture, and after boosting my input signal I make it oscillate at 1.8V using a 1.8V virtual ...
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unfamiliar notch filter configuration [duplicate]
This is a configuration of the notch filter that I saw in some design. It is very different from the Active Twin-T notch filter configs that show up on a quick google search. Any idea what is going on ...
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Analysis of an RCL Filter Utilizing a Potentiometer as R
I am trying to calculate the parameters ζ, Q, Fo, Gain (dB), and BW of this circuit. I am confident in the following equations:
Fo = 1 / (2 * π * √(L2 * C1)) ; Q = 1 / (2 * ζ) ; BW = Fo / Q
R2 = R5; ...
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How can I determine if a Sallen-Key filter will be stable using LTSPICE and analytical expressions?
I am trying to determine if a Sallen-Key filter that I designed will be stable. In order to do this, I am trying to simulate the filter in LTSpice and measure its open-loop phase margin.
The filter is ...
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Butterworth filter not getting as much gain as expected
Using the Analog Devices Filter Design Tool, I have created a band pass filter for a 1MHz input with 20dB of gain. I have implemented the circuit in LTSpice with the expected behaviour, however when I ...
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Is there a reason to use different sets of resistor values in the 2 stages of a butterworth LPF?
I needed a LPF for my design so I used Filter Design Tool from AD to generate one. The generated circuit includes 2 sets of resistors of different values, which I find inconvenient. Is there a reason ...
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What op-amp can I use in this output filter recommended design?
I'm working with the Cirrus Logic CS42448 codec and would like to implement an active filter output to differential audio signals.
The output should be line level to be connected directly to external ...
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High pass filter doesn't get back original signal?
If you simulate this (from https://www.circuitlab.com/editor/#?id=3p73kzybb5r8):
simulate this circuit – Schematic created using CircuitLab
You see this:
The input is a combination of the ...
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I want to implement a 2-active crossover circuit with LM833 and amplify it using LM386 and now the problem is I couldn't understand the circuit [closed]
I can understand up to certain level that we used a buffer, low pass filter but I can not connect with circuit and coming to components we used 120 Ω, 6.8 nF for active crossover with power supply + ...
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HP filter for MHz pulses
I need a high pass filter for my measuring setup and I'am a total newbie to analog filters. I have weak hf pulses (0.5-1.2 MHz, 10 mV) superimposed on lf sine wave (8-40 kHz, up to 5 V), I'm ...
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Calculate parameters of active high pass and low pass filter given for EOG circuit
The circuit is from here.
The opamps are : OPA2335 (dual channel because of horizontal and vertical electrodes.)
I don't exactly understand how to calculate R and C values based on the 0.5 high pass ...
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2nd order active low pass filter
Apparently the voltage of the inverting input to the op-amp in the 2nd order active LPF should be equal to \$v_2\$. Would anyone be able to explain why this would be the case?
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Why are active filters preferred over passive filters?
This question was asked to me in an interview. I replied that passive and active filters both have their merits and demerits :
Unlike passive, active filters provide mechanism for gain adjustment
...
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How to compare these parameters through a cost function?
I am comparing three filter designs based on different criteria. Basically my question is about what is like the best way to compute like a number, or figure of merit to evaluate this criteria.
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Calculated gain of inverting active high pass filter doesn't match simulation
I tried to find a solution in other threads, and I did find similar topics but nothing really helped me answer my question. I have a circuit, see here:
simulate this circuit – Schematic created ...
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How to design a Deliyannis-Friend biquadratic section?
I have opened a question yesterday regarding a mistake I am not finding in my Deliyannis and Friend design algorithm: Deliyannis-Friend design: where is my mistake?
Although I am still trying to find ...
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Sallen-Key LP design algorithm
I am facing this design from Analog Devices:
Image source: Analog Devices - Mini Tutorial MT-222, Sallen-Key Filters
I don't understand how they reach the value for the coefficient m. I did a sanity ...
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Multiple feedback design methodology
I am having trouble finding a step by step approach to the MFB filter. I came across a tutorial from Analog Devices but I am struggling to find what is the reasoning behind their equations, and can't ...
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Multiple feedback filters: Deliyannis? Friend? Rauch? Which one is which?
I am somewhat confused regarding the MFB filter naming custom. In the literature, I read of the Deliyannis form, the Deliyannis-Friend form, the Rauch form, and people seemingly confuse them.
There ...
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How to achieve the lowest noise configuration from a differential setup
I want to be able to capture a differential output from a shunt resistor. The shunt resistor differential voltage will range from 2.5mV to 50mV at 50Hz.
My initial idea was to send this signal through ...
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Determining values for active low-pass output filter for DAC
I'm trying to use a PCM1780 as DAC for my audio circuit. The datasheet shows the following recommended output schematic for this DAC, for which I'm trying to choose component values (because they do ...
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Multiple feedback band-pass filter issue in LT Spice
For a school project, we are tasked to make a band pass filter with a center frequency of 1000 kHz, 1 MHz. Everything works fine below 1.1 MHz. In the picture below, a sine wave with a frequency of 1....
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Wrong frequency response of an active HPF filter
I am trying to simulate an active high pass filter on OrCad, but the frequency response of it looks like a band pass filter, does anyone know why ?
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2nd order high pass filter with two real poles
I want to implement an active analog high pass filter, which behaves as a high pass filter implemented by a capacitance, an inductance and a resistor in the following way:
simulate this circuit &...
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Adding an active low pass filter to circuit changes voltage from 2-3V (0.5v amplitude) to 'dc' 2.5v but doesn't when separate
I have circuit that contains a summing amplifier as well as other components previous to it. I am trying to add an active low pass filter to limit frequencies above 50Hz. It works perfectly on it own, ...
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Power meter integrated in a circuit
I am constructing an electronic circuit that requires a power meter with a voltage signal output that represents the changes in power in a resistive load. It is crucial that the phase of this signal ...
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What is the correct way of amplifying the output of an active filter?
I have been trying hard to implement a narrow band pass filter using operational amplifiers.
Here is the circuit:
So far, I was able to get correct result in spice simulations, but when I put the ...
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Design an AGC circuit for microphone using JFET
At the beginning of the circuit, I designed a 20Hz to 20kHz second-order Butterworth bandpass filter circuit, and then I tried to pass the filtered signal through an AGC circuit to achieve a smooth ...
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Transfer Function of Multiple Feedback Bandpass Filter in a specific format
I've been trying to study the Multiple Feedback Bandpass Filter.
I managed to find the transfer function and the natural frequency of oscillation.
$$\frac{V_\text{out}}{V_\text{in}}(s) = \frac{2\...
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Design of a band-pass filter with automatic gain control using a JFET
I have implemented this circuit which is supposed to do AGC and filter out the signal between 20 Hz-20 kHz, but it seems have some problems. The bandpass filter works well, but the agc circuit doesn't ...
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Why Is There a Parasitic Sine Wave at My Signal
I am trying to build an EEG device (following the openEEG open source design). I amplify the small EEG signal with an AD620AN intrumental amplifier, then pass it through a high pass filter to ...
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Narrow band band-pass filter design with LM358 op-amp
I am trying to design a narrowband band-pass filter with an LM358 op-amp, single supply 0-5 V. My requirement is a gain of 30 dB at center frequency 4 kHz and 20 dB attenuation at 3 kHz and 5 kHz.
I ...
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How to get the DC gain out of this? [closed]
The question is:
In the filter circuit shown, R1 = 10kΩ, R2 = 10kΩ, R3 = 4kΩ, R4 = 6.8kΩ, C1 = 5.3nF, and C2 = 5.3nF. 1 nF = 1 nanofarad = 10-9 farads. What is the DC gain of this filter? Calculate ...
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My low-pass filter is strongly attenuating very low frequencies
Problem
I have designed an active low-pass filter using Sallen-Key architecture. It is a 4th order filter (two 2nd order stages cascaded). Here is the circuit diagram:
simulate this circuit – ...
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TPA3116D2 amplifier with Sallen-Key low-pass filter on TDA2030
I have a 2 x 50 W TPA3116D2 (VHM-302) amplifier and a Pioneer TS-G1345R 35 W, 4 Ω speaker. When connecting them, there is no problem and the sound is good.
However, I wanted to build a low-pass filter ...
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How do the stages of this high pass filter work?
I am trying to understand exactly how the stages of this Moog high-pass filter work but I still have several things that I cannot quite figure out:
Q13 and Q14 form a push-pull amplifier, and are ...
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BJT Active low-pass filter frequency calculation
The left BJT of this circuit acts as a low-pass filter.
According to Simple transistors Low Pass filter, where I found this schematic, its cut-off frequency is 150 Hz.
How do we calculate this ...
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Issues associated with a single layer PCB for an RLC band pass filter
I have an issue the design of an RLC band pass filter with bandwidth ranging from 5kHz to 15 kHz. I simulated the given circuit in Proteus. It worked perfectly fine there. I then tested it on a ...
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4th order transfer function
I have a 4th order transfer function. Given transfer function is below.
If given transfer function had been 2nd order transfer function, it would easily be factorization of transfer function like:
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Active notch filter behaves like a low-pass filter
I'm trying to build an active notch filter centered at 50 Hz. I'm trying to wire it using a breadboard but I'm facing some problems with the output signal.
Before wiring the circuit, I tried to ...
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How is the value of constant \$\zeta\$ calculated in the next second-order low-pass filter?
I was given a couple of problems about active filters, but unfortunately I have a little doubt about the resolution; the problem states:
Design a second-order low-pass filter with a cutoff frequency ...
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Multiple feedback bandpass filter calculations are wrong when C1 and C2 are different values
I wrote a simple Python program to calculate a single MFB bandpass filter and I am getting different values for Q and bandwidth if the C1 and C2 are totally different values. If I check with a ...
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Analog filter gain in simulation is not as expected
I want to have a 1 stage analog active filter with a cutoff frequency of 26 kHz. I used the MATLAB analog filter design toolbox to create such a filter. The filter that was provided by MATLAB looks ...
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Meaning of 'Bessel Filter'
Question
I'll get straight to the narrow point ahead:
I'd like an expert's opinion on the appropriate use of Bessel when considering a specific 4th order bandpass design.
I don't mind a more general ...
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RC-OTA versus gm-C integrator in CT Delta-Sigma
In the book "Understanding Delta-Sigma Converters" of S. Pavan, R. Schreier and G. Temes they are stating the following speed comparison of the RC-OTA and gm-C integrator:
The impressive ...
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How to reduce oscillations in this active filter circuit?
I am trying to build an active filter that takes a tail pulse (~100 ns rise, 100 us fall) from a preamp and shapes it into a Gaussian to be read in by an ADC. I've come as far as getting a good ...
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Does max OP Amp Capacitive Drive Capability Matter with Active Filter?
I know that every OP Amp does have a limited capacitive load drive capability.
Even if not specified, it is always a good practice to use a series isolation resistor.
Anyway; when looking at an active ...
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What kind of filters can be used for filtering high amplitude signals? [closed]
I want to build a filter that only allows signals with big enough amplitude to pass. Where should I start?
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Active band-pass filter design questions
I am trying to design an active bandpass filter using a uA741 op-amp, and I am having trouble finding where I made a mistake. My math seems to check out, but when I test it in PSpice it doesn't work ...
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How does the GBW of an op-amp affect the position of the passband cut-off frequency in a low-pass filter?
Let's say I have a 2nd order low-pass filter in a Sallen-Key configuration (Chebyshev), and the cutoff frequency should be the frequency at which the phase shift becomes -90°, how will the GBW (gain ...
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