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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Very high frequency band pass filter

I designed a band-pass filter. I set the center frequency to 90 MHz. When I do an AC analysis, I see the filter graph I want, but the transient analysis results are not what I wanted. I'm giving a ...
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How to choose digital potentiometer bandwidth for filter?

We want to use a Digital potentiometer for an active bandpass filter. But we do not know how to choose the bandwidth of the potentiometer. The center frequency of the filter will be 90MHz. Should I ...
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PSpice and calculations don't add up for an active band pass filter

I designed a basic active band pass filter and used these equations to come up with a center frequency of 29.9 kHz: $$f_0 = \frac{1}{2\pi\sqrt{(R_1||R_2)*R_2*R_3*C_1*C_2}}$$ In PSpice, it looks like ...
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LC Topology for band-pass filters

I, as a beginner, am looking to design a passive band-pass filter for a crossover speaker system. This project that I am doing has the following specifications: The filter should be a Butterworth ...
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1answer
65 views

Frequency response of a low-pass, band-pass, and high-pass adder circuit

I'm doing a project and one of the steps consists of filtering a signal through a low-pass, band-pass and high-pass filter. All the filters are Sallen-Key with a passband gain of 1. The pass-band ...
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1answer
63 views

Difference in Bode plot with table and Bode plot in Matlab

I am trying to generate a Bode plot for a transfer function of a high pass circuit. It's part of a solution to another question but this is the part that is confusing me. I have a transfer function: ...
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180 views

What is the transfer function of this bandpass filter?

I have this bandpass filter for which I'm trying to get the transfer function. The amplifier is not idead and has an open-loop gain of 100k and a gain-bandwidth product of 10MHz. I tried everything ...
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2answers
104 views

Constant failure in bandpass filter simulation

some of you probably remember my last question, but I like to reiterate: I created a bandpass filter with the help of the online tool FilterWizard, which should block below 30 kHz and above 300 kHz; ...
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58 views

Is there a way to further optimize this band-pass filter?

Is there a way to further optimize this band-pass filter created by FilterWizard so that it completely blocks below 30kHz and above 300kHz? I played a little with the numbers and found that (in this ...
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117 views

Why is my active passband filter (LP and HP Butterworth filters in series) not working?

I did each filter alone and they work fine, but when they are made together to form a bandpass filter with the same components I used they don't work. The output on the oscilloscope is a very weak ...
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1answer
188 views

Why is my narrow bandwidth multiple feedback active bandpass filter oscillating?

When I put the following narrowband active bandpass circuit on a breadboard, using a MCP601 single-supply CMOS op-amp, it just oscillates at about 339 kHz with a Vpp of about 1.36 V at a supply of 5 V....
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129 views

What's the difference between these two Sallen-Key bandpass filters?

I am thinking about using a Sallen-Key bandpass filter for an audio project I am working on. While trying to understand the circuit, I came across two similar, but slightly different circuits. The ...
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How to calculate multiple pole active filter manually?

For example I want to make a 6-pole multiple feedback topology active bandpass filter that have the specifications of 0.25 db chebychev , that the range of the filter is 2000 hz to 3000 hz. I already ...
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2answers
252 views

Building a band-pass filter using an op-amp

I am quite new to op-amps but have looked at them in college and have done my own research on them. I am trying to use an op-amp to build a simple band-pass filter which has an in-band voltage gain of ...
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How do you combine 3 existing band pass filters to make a triplexer with 50 Ohm ports?

I have designed 3 microstrip band pass filters that each have a good 50 ohm match at the target frequencies (2 m, 70cm and 13cm bands) and I want to combine them into a triplexer to split one signal ...
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What is the difference between these two Active Bandpass filter circuits?

Both are bandpass filters. The circuit in figure 1 is easy to understand and I can calculate the gain and cutoff frequency without any problem. Regarding the configuration in figure 2, I would like to ...
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1answer
58 views

Apply S-Domain Notch to Time Signal

I have a signal in time domain which shows an 8Hz oscillation. I've designed a notch (band-stop) filter in frequency domain (S domain) to filter this 8Hz oscillation. Notch design parameters are Width,...
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3answers
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Help identify ECG signal acquisition using AD2

I have recently got into electronics. I have access to an Analog Discovery 2 (AD2) kit with signal generator and oscilloscope functions. I have been trying to teach myself how to use this equipment ...
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Getting an error in Proteus while simulating the following circuit

I have built a circuit with a series of bandpass filters to detect specific frequencies. While simulating the circuit on Proteus, I was getting the following error. I tried looking for a solution to ...
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713 views

Cutoff frequency of RLC band pass and band stop filter

I have found in a website that the cutoff frequencies of a series RLC bandpass and bandstop filters are: $$ f_c = \sqrt{\left(\frac{R}{2L}\right)^2+\frac{1}{LC}}\pm\frac{R}{2L}. $$ This is the link ...
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How to properly design LC bandpass filters?

A little disclaimer. Electronics is a hobby to me so I learn it on my spare time. This leads to certain knowledge gaps that professionals might not have. I want to build a good filter using SMD ...
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1answer
256 views

Is the resonance frequency actually at the center of the passband of a bandpass filter?

Assume we have the following circuit It is a band-pass filter. There is something I don't get. We know the the resonance frequency is given by \$ f_{Resonance}=\frac{1}{2\pi\sqrt{LC}} \$ and we know ...
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223 views

Signal is always attenuated by passive bandpass filter

I'm trying to build a passive bandpass filter with the cutoff frequencies of 0.001 Hz and 10 Hz. It seems that my signal is always attenuated. Why?
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326 views

Why does a buffer amplifier change the behaviour of a bandpass filter?

Why does the implementation of a buffer amplifier separating the high-pass and low-pass filter of a bandpass filter affect the transfer function of the bandpass filter? I thought the point of a buffer ...
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Is it possible to acheive a band pass filter with a pass bandwidth sufficient to discriminate AM radio channels, without using an inductor?

I am wondering if it is possible to make a filter circuit that has a high enough Q/small enough pass bandwidth to discriminate AM channels, which are spaced 10 kHz apart in the ~1000kHz range - so ...
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75 views

Designing a band pass filter using given specifications

I am trying to design a band pass filter using the below emitter follower circuit : The Specifications for the filter include : $$ Z_{in} = 16k\Omega \\ \text{Current gain} = 35dB \\ \text{3dB ...
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Is the system linear, time-invariant and causal? Does the decomposition property hold? Sallen Key bandpass filter

I have this ordinary Sallen Key bandpass filter: - simulate this circuit – Schematic created using CircuitLab I'm being asked, if the system is linear and/or time-invariant and/or causal. ...
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1answer
123 views

Band-pass op-amp structure with parallel diodes in feedback?

It's been a while since I've done analog circuit theory, and I'm trying to interpret the 2nd gain stage sub-circuit in this schematic for a guitar pedal: I'm not sure if I'm approaching the circuit ...
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69 views

RLC band pass filter — getting the correct phase

Consider the RLC band pass filter circuit: I’m trying to construct this circuit with a maximum of the transfer curve at \$f=5-6\$kHz and bandwidth \$\beta=2\pi \cdot 2\$kHz and so I have chosen a 88k\...
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Coupled Line Bandpass Filter

I am trying to design a microstrip bandpass filter in ADS with a center frequency of 2.4GHz and a fractional BW of 10%. My results from the schematic look great: When I move to the layout and EM ...
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68 views

Filter Q factor with 4 pole filter question

I am designing something related to a vocoder and I need 10 filters with certain specifications and I am confused about the required Q factor. The specifications of the 10 filters that are needed are ...
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2answers
141 views

Why do 2 different online active filter calculators give way different GBW requirements for the same frequency range?

I am confused about 2 different online active filter calculators giving different GBW requirements for the same frequency range. One calculator is giving GBW requirements in the kHz range while the ...
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1answer
62 views

How does this notch filter work? [duplicate]

I am trying to learn filters. In the following circuit, the author says that negative and positive feedback are used. I couldn't understand what the circuit parts do. Actually I got the negative ...
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1answer
184 views

Variable band-pass filter for splitting audio signal into separate signals (high and low freqs)

I've been wondering for quite some time how to create a sort of audio splitter. The idea is to get an audio signal (e.g. guitar) at the input, and have two separate outputs, one with the input's low ...
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2answers
572 views

Detect an IR signal with a photodiode to use it with a microcontroller

I am trying to detect an IR signal with a photodiode to connect it to my STM32F411 and use it as a trigger signal. The signal I send are two pulses at 500 kHz which looks like this: I am using a ...
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Bandpass filter obtained by complementary transformation of lowpass Sallen & Key: what went wrong?

I am considering the following lowpass Sallen & Key filter: My components are the following \$R_1=10 k\Omega\$ \$R_2=10 k\Omega\$ \$C_1=150 nF\$ \$C_2=1.65 nF\$ Now I have performed a ...
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Can I change a frequency band of an EQ board?

Is it possible to change one of the frequency bands of this EQ board? In particular, the low frequency adjuster is 100Hz and I want to make it 60ish Hz. My understanding is that i need to meddle with ...
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1answer
78 views

Why won't the bandstop filter work in this circuit?

This is the EMG circuit I designed. The cut off frequency of the bandpass is 20-3k Hz. This somehow worked already. But the bandstop filter doesn't show. Why is this? This is the freq-vout graph and ...
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2answers
170 views

Modifying an op amp filter to use single supply

I'm having much difficulty modifying a "state variable" bandpass filter from being dual supply to single supply. (https://www.electronics-tutorials.ws/filter/state-variable-filter.html) Here ...
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1answer
65 views

Not getting expected band pass filter response

I am trying to make a LTE signal repeater and trying to filter all other signals except the band 3 (869 - 894 MHz) This is what I am getting: This is the circuit: ...
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1answer
310 views

KHN biquad: why does LTSPICE plot a wrong phase plot for bandpass filter?

I'm studying the KHN biquadratic section and its outputs to obtain a lowpass filter, a highpass filter and a bandpass filter. I simulated the filter using Mathematica and obtained the following plots, ...
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2answers
280 views

Band-pass filter vs. Serial Low-pass+High-pass filter - Is there a difference?

Is there a difference between a band-pass filter (BPF) and tying a low-pass filter's (LPF) output to the input of a high-pass filter (HPF)? It seems to me that they should do the same thing---or ...
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255 views

Does it looks like a bandpass matching network?

I am trying to understand this receiver and figure out what does this L-C network is. I read about matching networks and found this example, I am curious if it is the same thing. is it? In the ...
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217 views

3 band audio equalizer circuit transfer function

I am trying to find the transfer function of part of a 3 band audio equalizer circuit that amplifies low frequencies but I am confused about the topology. Here is the topology: I was under the ...
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1answer
180 views

Why does this high pass filter behave like a band-pass filter on Multisim AC Sweep simulations?

I have this high-pass filter schematic and its AC Sweep simulation. Until the break through the end, the graph is right, but I can't see why the graph breaks on the right hand side and the filter ...
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77 views

Low-pass (band-pass) filter for op amp circuit

I have a circuit that amplifies a one-shot inductive trigger pulse of about 1.3Khz (@780 micro sec period) from about 10-200mV to about 3-4V. Between C1 and R3 there is a 0.13uH inductor coil with 11 ...
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211 views

Design an active bandpass filter to get 1.5MHz peak frequency and 300KHz band

I have this question in Linear Circuit Analysis course where I need to find the values of R1, R2, C1, C2, of the given bandpass filter circuit in order to get a peak frequency wp = 1.5 MHz and a ...
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105 views

How do I check the stability of Multiple pole feedback Bandpass filter?

Is it possible to find stability measures like Phase Margin or Gain Margin for Multiple feedback Band Pass Filter? The circuit is as shown below,
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298 views

How can I model an optical filter using python?

Say I have an RGB LED which transmit intensity modulated signals, at one symbol transmission I want to send a symbol with all three chips.. Can I just model three bandpass optical filters like RF ...
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1answer
531 views

Using active BPF to convert a square wave into a sine

I have an inverter that converts 24 V DC to a 48 VAC peak-to-peak square wave with a frequency of 55 Hz. I am then going to use a step-up transformer to output 120 VAC to power some rocket valves that ...