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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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Low capacitance value capacitors in LC bandpass filter

I am going to try to build a Butterworth LC bandpass filter. However, using some online calculators result in some very low value capacitors (sub-1pF). I am thinking that the performance will not be ...
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Band pass filter implementation using 741 op amp

My assignment for a school project on Circuit Theory, is to construct a Band Pass Filter at least 3rd order with a stop band around 20kHz. First things first, I need to design the circuit. I have to ...
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Why is superheterodyning better than direct conversion?

What is the advantage of having the extra stage of IF, extra local oscillator and extra filtering stage and amplification. It just seems like more work and circuitry. Surely the direct conversion to ...
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Tradeoffs for creating higher order butterworth filters

I am working on a bandpass filter to filter the output from a hydrophone. This is my first time designing a filter and using a cookbook from TI, I built a 4th order Butterworth filter with two partial ...
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103 views

How to generate this kind of filter?

I've been trying to understand this exercise proposed by my teacher. He asked us to find a combination of 2 ideal filters to generate a filter within the conditions of the image below. (That means, ...
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RC bandpass filter using two port network parameters?

So my assignment is about exploring two port networks and the use of the 4 parameters, now one of the tasks is to design a bandpass filter with cascaded high pass and low pass filters, now I am really ...
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46 views

Why Deliyannis bandpass filter with high Q does not have the expected transfer function bode plot

What i need is to design a delyiannis band-pass filter with Q enhancement technique. The theoretical analysis of this technique is referred here in pages 107-112. For those who don't know how to ...
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45 views

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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74 views

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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72 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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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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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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243 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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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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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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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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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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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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456 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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286 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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91 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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75 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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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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199 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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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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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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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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263 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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1answer
68 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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279 views

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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725 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
526 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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87 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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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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374 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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516 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 ...