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Questions tagged [band-pass]

Bandpass is an adjective that describes a type of filter or filtering process; it is to be distinguished from passband, which refers to the actual portion of affected spectrum. Hence, one might say "A dual bandpass filter has two passbands." A bandpass signal is a signal containing a band of frequencies not adjacent to zero frequency, such as a signal that comes out of a bandpass filter.

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Parallel RLC bandpass filter Bandwidth incorrect

I have been trying to create a bandpass filter with the cut-off frequency at \$\mathrm{200Hz}\$ and \$\mathrm{4800Hz}\$ I have managed to get the centre frequency to \$\mathrm{2500Hz}\$. The bandwidth ...
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Passive band-pass filter conceptual analysis

I'm trying to chain a high-pass filter and a low-pass passive filter together to form a band pass filter to illustrate how you can combine filters together, but I'm having issues trying to understand ...
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Are these two circuits the same?

Are these rwo circuits the same considering the right hand sides of them where it is parallel for the C&R and C&L(meaning the way i should obtain the frequency response? And for the longer ...
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Ultrasonic transducer actual bandwidth for filtering

I have a pair of ultrasonic transducers with a "Thick Resonant frequency" of 975 kHz ±30kHz according to the data sheet. I did a frequency sweep test where I could see that they performed best at a ...
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67 views

Easiest way to find transfer function of a lossless ladder filter after we finish design?

I have completed my Lossless Ladder BPF design, but I don't know how to find the transfer function of the resulting circuit without going through the slow and rigorous process of getting resistances ...
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133 views

How do I create a working bandpass filter in LTSpice?

I am attempting to create a bandpass filter in LTSpice. I am fairly new to the program, which is probably contributing to my difficulties. The filter I am creating needs to have a center frequency of ...
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57 views

Designing a Band Pass Filter

I need a band pass filter that only accepts frequencies from 1000 to 1400 Hz and then toggles the transistor. It has to work from .1 Vpp to 1 Vpp and rejects anything else. I have been testing this ...
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154 views

Designing 4th order Butterworth Multiple feedback bandpass filter

I'm trying to design a 4th order Butterworth bandpass filter using Multiple feedback topology. The design requirements I am trying to achieve for this filter are; Q factor = 10, Av = 11, fc = 100kHz ,...
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What is the difference between a Sallen-Key Band pass filter and a band pass filter?

Am currently doing an assignment on sine wave generation and am using a sallen key band pass filter - i am unsure what the difference between the band pass filter and the sallen-key band pass.
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Parametric Equalizer with State Variable Filter

I'm new to this forum but hope to get some answers to a project I'm working on. I'm trying to build an parametric equalizer with several bands (5 Bass-Bands, 3 Middle-Bands, 3 High-Bands). In the ...
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85 views

Digitally selectable filter

I have asked a similar question but I did not get an answer, as it was too specific. So I will build on it but make it a bit more broad spectrum. I would like to make a digitally selectable BPF using ...
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Butterworth bandpass - higher roll-off than expected

I am looking into filters, and i am using FilterLab and MATLAB's Filter designer. I know that i need to make a bandpass filter, with a roll-off of about 48 dB/octave. This is quite high, and i would ...
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Semtech LoRa sx1276 transceiver IC: modifying its reference matching network

After reading the following post: sx1276 Understanding matching network and having some followup questions, I wondered if I could just remove all the passives (optimizing PCB real state) and go from ...
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Transfer function of a bandpass

i was doing some homework and one thing I had to do was to derivate the transfer function of a given bandPass. I have done it myself but i dont know if it is correct nor if i followed the right path / ...
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First-order analog active bandpass filter with variable center frequency

I've thought about designing an active first-order bandpass filter with variable center frequency and fixed bandwidth, using OpAmps, as a project for an Applied Electronics class. My first try was to ...
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Active band pass filter that looks like a sallen–Key topology filter

I was using the Analog Devices design Wizzard in order to design a band pass filter with theese characteristics: Gain : 23 dB Passband: -3dB at 15 KHz Stopband: -40dB at 40 KHz The filter has 4 ...
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243 views

Calculating Phase/Time Delay induced by a 2-pole Bandpass filter? ie. Group Delay?

If you have a two-pole Butterworth bandpass filter described by a particular Q value (Q>0.5) and a resonant center frequency "f", is there any equation that will tell you the phase/time delay induced ...
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Predicting decay time of a resonant bandpass filter?

In a typical resonant bandpass filter, resonance is set as none at 0 and full at 1, such that the filter rings infinitely at 1 and not at all at 0. If there is a two-pole resonant bandpass filter, ...
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152 views

whats the difference between a cascaded band pass filter and a normal band pass filter (Audio visualizer)

simulate this circuit – Schematic created using CircuitLab currently im building an audio visualizer i would like to know what is the difference between a cascaded 2nd order band pass filter ...
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75 views

components used to make a butterworth filter

I doing some amateur radio experimentation and want to create a bandpass filter. I believe that a Butterworth filter would be good because it has a flat frequency response in the pass band. My center ...
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Band Pass Filter Equivalent Components

I am designing a very simple first-order RC band pass filter with cutoff frequencies \$f_l = 0.5 MHz\$ and \$f_h = 4.5MHz\$. I have it pictured below (I'm using 5Spice): This filter acts the way I ...
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345 views

I need to design a bandpass filter by cascading passive high pass filter and passive low pass filter

I have a low pass filter with 3db cut off frequency of 200Hz and a high pass passive filter with 3db cut off frequency of 2kHz. I need to design a cascaded band pass filter which will isolate ...
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Band Pass Filter for musical note separation

I have a school project that i need to separate musical notes with filters at least i thought that i can do it with band pass filter, here are the results These are the resistor and capacitor values ...
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226 views

Quality factor limit for 2nd order RC passive band-pass filter

simulate this circuit – Schematic created using CircuitLab I'm designing a 2nd Order passive RC band-pass filter and found that the quality factor is given by: \$Q=\frac{\sqrt{C_1C_2R_1R_2}}{...
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67 views

Loss due to impedance matching in a filter

I have a quite basic question, after starting to re-read some RF theory. If a voltage source has a resistance of 50 ohms, and the equivalent impedance of a connected bandpass filter and its load are ...
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73 views

Impedance calculation

How can I calculate this band-pass filter input impedance? I know from the datasheet that the Ri and the R0 of the ampop are 2M\$\Omega\$ and 75 \$\Omega\$ and the Gain at the central frequency is 30 ...
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Natural frequencies of a bandpass filter

I have the following frequency transform used to design a low-pass prototype out of a bandpass specification mask: $$\omega=\frac{\omega_0}{B}\left(\frac{\omega'}{\omega_0}-\frac{\omega_0}{\omega'}\...
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159 views

How to calculate the gain of a RLC tank filter?

I'm supposed to create a passive bandpass filter to select a reasonably sinusoidal 750 Hz signal from a 250 Hz square wave. Since we have very limited choices for the inductor (0.03 H) and capacitor ...
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158 views

Determine by the order of transfer function what kind of filter

How can I determine by looking at the following tranfer function, that is this the transfer function of a band-pass filter: $$\frac{1}{as^3+bs^2+cs+1}$$
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145 views

Is it possible to filter a frequency?

I have built and tested an active band pass filter, with the intention of creating a speed detector, whose lower and upper cut off frequencies are 48 Hz and 1591 Hz respectively. During testing I ...
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174 views

What bandpass Q factor do I want for 12dB/octave roll off?

Sorry for what may be a dumb question. I'm used to thinking about low and high pass filters in terms of db/octave (e.g. 6db for passive RC filter). Whats the equivalent Q factor for a bandpass ...
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221 views

LC band pass filter

I'm looking at implementing an LC bandpass filter, where I want upper and lower cut off frequencies to be 1254 Hz and 48 Hz respectively. Based on the pictures I've added - from http://www.radio-...
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AC voltage through a capacitor

I've built a band pass filter to detect speed using a radar motion detector (IPM-165 http://nic.ath.cx/PDF/sensors/radar/CDM324-doppler/InnoSenT/InnoSenT_application_note_III_11_06.pdf). Using PSpice ...
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Analysing a band pass sallen key filter

I'm trying to understand the transfer function of the band pass sallen key filter, which looks like: With the following circuit: How can I analyse it to get the transfer function? Thanks for any ...
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219 views

Twin-T filter decay rate (drum circuit)

I'm building a Twin-T active bandpass filter as shown on this schematic: simulate this circuit – Schematic created using CircuitLab My aim is to build a simple drum-like synthesizer that ...
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66 views

Grounding oscilloscope probe effects

I have built an active band-pass filter on a breadboard with the use of an MC33078p op amp. Gain is 32 on paper. When I apply the AC signal to the circuit, 18.1mV P-P and 660kHz, the oscilloscope ...
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Band-pass and LM358 based rhythmic light

I was asked by a friend to build a simple circuit to have a light flash depending on the bass of a song (mainly techno music). This is my idea: The circuit works on 9V to be powered either by ...
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Pole/Zero plot is the same for passive and active (w/ gain) bandpass filter, why?

I have designed an active inverting bandpass filter, and when comparing its pole zero plot to a passive bandpass fitler with the same cutoff frequencys, the pole zero plot is exactly the same, even ...
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526 views

Deriving Bandpass Transfer Function

I'm designing a bandpass filter and have been doing some reading on it. I found a transfer function describing the circuit (which apparently all formulas describing this circuit are derived from): $$...
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6answers
434 views

Can a filter change the frequency of the input signal?

I am given a square wave with Vmin = 0V and Vmax=5V , T(period)=8ms and duty cycle 25%. I am asked to find the properties(low cutoff , high cutoff , bandwidth) of a band pass filter that will make the ...
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84 views

Band pass filter , component values

The input of the band pass filter is 30Khz triangular wave of 1Vpp. I want the band pass filter to allow 27k-33k Hz . I have used these values based on the formulas I found online for this band pass ...
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4answers
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Completely different circuit response with 1000kΩ than with 1MΩ resistance

I have the following circuit (a band-pass filter) and I cannot understand what's the difference of a 1000kΩ resistance to a 1MΩ as seen here: With R223 = 1000k, my circuit outputs the expected ...
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320 views

triangle wave form to sine form through band pass filter

Why and how does this active band pass filter change a triangle form to a sine form? I know that the band pass filter consists of a low pass and a high pass , so it cancels out some frequencies , but ...
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445 views

Band pass filter , circuit analysis

So I have found the circuit for a band pass filter. I know its function and what it does, but I haven't understood yet why its components are placed were they are. Why are the capacitors and the ...
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1answer
341 views

Transfer Function Of Multiple Feedback Bandpass Filter

I am trying to figure out the transfer function for this bandpass filter (images below). I am sorry for badly drawn circuit. The operational amplifier is an ideal op amp. I'd like to know if I ...
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129 views

Why is the gain of this LC two-port network infinite?

Consider the following two port network, where a voltage is measured across the output terminals (no current), and the input is connected to an AC power source: Calculating the voltage gain of this ...
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LTSpice Transconductance Amplifier Simulation

I'm trying to simulate a band-pass transconductance amplifier in LTSpice, which looks like this: I used the recommendations of this post - https://electronics.stackexchange.com/a/278870/87695 - and ...
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251 views

How to pass a square wave through transfer function in MATLAB?

I am currently trying to create a band stop filter which attenuates frequencies between 2000Hz and 8000Hz. I have got the transfer function but now I am struggling to find the documentation on how to ...
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349 views

How to determine the RLC values for a bandstop filter

I've been looking through the vague online documentation for designing a basic bandstop filter. I have the two frequencies which I want to attenuate but I cant seem to find how to calculate the values ...
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Why do inductors like these do not work

I was trying out a series RLC band stop filter on hardware but for some reason it was not working, I later figured out that the culprit was the inductor after testing both inductor and capacitor via ...