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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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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284 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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304 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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341 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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592 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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2k views

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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420 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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74 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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270 views

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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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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683 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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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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151 views

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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567 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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651 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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530 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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154 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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989 views

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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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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444 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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3answers
165 views

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 ...
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How would one design a circuit to detect energy in the 3-140GHz ranges economically

We are looking to make something to detect RF frequencies in the SHF and EHF bands, from 3-140GHz, without requiring much frequency or amplitude accuracy. It would be ideally split into a few bands, ...
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527 views

Center Frequency Shift Bandpass Filter

I have set Tow-Thomas filter to get bandpass output. I want center frequency to be precise as much as possible. If there occurse center frequency shift in the lab, what are possible way to compensate ...
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968 views

How to find Vout for the following band pass filter

I have a problem finding the following Vout for this circuit. Is it possible to just use the following formulas that i have shown. I am just unsure due to the resistors. I assume that what i have ...
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332 views

UPDATED:How to do Band Pass Filter Analysis for the current circuit

For the following circuit i am having trouble finding the following respective cutoff frequencies as i am unsure on if i need to take in to account R3 for the high pass portion. Also for the low pass ...
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596 views

Understanding Parallel RLC circuit

I am currently going through the MIT 6.002 lecture videos to help prepare me for my upcoming electronics final, and I came across something that I didn't quite understand https://youtu.be/WT-qzgaKeGI?...
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95 views

Cascaded Filter Output Not Correct

I am simulating a speaker system with tweeter, woofer, and midrange speakers. I know my values for the components are all correct, but the output plot is a little off. The passbands should be a little ...
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187 views

Fourth-order bandpass filter Bessel - I can not solve the final part (math accounts)

With the previous gain function you calculated, design a Bessel fourth-order bandpass filter with center frequency \$f0 = 10 kHz\$ and bandwidth \$Bf = f0/10\$. I did the calculations with the ...
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Designing a circuit from a transfer function

I have this transfer function of a bandpass filter with 2 poles and 2 zeros: $$ H(s)= 10^{-0.8} \frac{\left( \dfrac{s}{10} +1 \right) \left( \dfrac{s}{100.000} +1 \right)} {\left( \dfrac{s}{100} +1 \...
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Are cutoff frequencies of bandpass and bandstop filters equal?

Consider the two filter in picture simulate this circuit – Schematic created using CircuitLab Are the cutoff frequencies (i.e. the two frequencies at which \$V_{out}=\frac{1}{\sqrt{2}} V_{in}\$...
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692 views

Bandpass Filter Design

I'm trying to split an audio signal ranging from 20Hz - 20kHz into five ranges of 0 - 250Hz, 250Hz - 500Hz, 500Hz - 2kHz, 2k-6kHz, and 6kHz - 20kHz. I've been trying to design the "Inverting Band ...
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700 views

Picking the right opamp

I've been designing some active bandpass filters and, while in simulations it works great with ideal op amps, I'm not sure how to go about picking an op amp from a distributor. Obviously there are an ...
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536 views

Bandpass Filter Attenuation?

I'm trying to split an audio signal into 5 channels, letting 5 different ranges through each filter (low, mids, highs, etc..). What I'm finding is that each bandpass filter has different levels of ...
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4answers
1k views

LCR circuit with squarewave input: Why does the output take a decreasing amplitude through each cycle?

I understand a square-wave will be made up of a sum of sine waves in the form $$\frac{1}{n}sin(nf_0)$$ So when a squarewave is input to a LCR circut designed to be a bandpass filter, it will ...
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4answers
256 views

Filter-Amplifier circuit for Low Voltage I/P circuitry

I'm designing my first ever circuit for a hobby project. I've a sensor that outputs in mV (1 to 2) and a controller with ADC. The ADC is 16 bits, VDDA = 3.0 V, Temp = 25 °C, fADCK = 1.0 MHz. Since the ...
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293 views

Op-Amp Input Bias Compensation for Multiple Feedback Filter

I'm adding an input bias current compensation network to the positive op-amp input of my band-pass multiple-feedback filter. I'm setting the source impedance for the positive input pin equal to that ...
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1answer
262 views

Problems with implementation of a band-stop filter on an MCU (dsPIC) using fixed-point arithmetic

I'm trying to implement a band-stop (notch) filter on a microcontroller dsPIC33EP64GS506 to filter out a 100 Hz component from ...
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2answers
952 views

Band-pass filter doesn't work

simulate this circuit – Schematic created using CircuitLab I designed this as it would pass frequencies between 400-600 Hz. But it passes every single frequency anyway. What is the problem?
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452 views

Need help on-parallel resonant circuit vs. bandpass filter!

These two types of circuits, parallel (LC) resonant and bandpass filter (i.e. some resistance connected with parallel resonant circuit in series). Please tell me when to use which one and what are the ...
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87 views

How could I design a circuit for a solar panel so that it only produces output from a red laser?

I'm designing a little laser tag system with some arduino's as a little project for Christmas break and I'm having trouble figuring out how to make my solar panel receive information from my laser ...
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3answers
253 views

Order of the filter

I can't seem to figure out the order of the filter. With the knowledge i have, "The order of the filter depends on how much change there is in the (20x)dB/decade in the amplitude response." If it ...
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742 views

Second Order Bandpass Filter vs Second Order High Pass and Low Pass in Series

Is using a second order bandpass filter less effective than using a second order high pass filter and a second order low pass filter one after the other? I tried a bandpass filter to filter out ...
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794 views

Advice on 4th-Order Bandpass Filter

I am trying to design a 4th-Order bandpass filter with the following specifications; centre frequency 30 MHz, bandwidth 5 MHz and of course minimising loss. I present my current design below which I ...
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5k views

The Cutoff frequency of bandpass filter

Given: Center Frequency f0 = 2.2KHz Q factor = 5 The problem I'm facing is this: How do I calculate the 2 cutoff frequencies of this band pass filter? I'm confused because my question says "The ...
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1answer
375 views

Sallen-key second order bandpass filter low frequency response

I have designed a Sallen-Key bandpass filter with a centre frequency of 5000 Hz, a Q factor of 2 and an H0 of 5. I am trying to figure out why it responds as seen here to square wave with a ...
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5k views

Designing a multi-stage BJT amplifier

For my final lab this semester, I've been tasked with designing a multi-stage amplifier that serves as a receiver in a laser tag set that we've been building over the course of the class. I've ...