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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42 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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58 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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55 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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97 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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52 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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39 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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311 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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39 views

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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32 views

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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68 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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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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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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78 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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118 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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157 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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97 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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53 views

Why does this high pass filter behaves like 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 filter behaves ...
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60 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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94 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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43 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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187 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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218 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 ...
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575 views

Low pass filter not working properly

This is the pass band that I'm using to filter some EMG signals through electrodes. When I test it with multisim it works really well as you can see, but when I test it with real equipment (...
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111 views

Design a Band-Pass Filter

Recently I came across an exercise which I can’t confirm myself If I’m doing it right. The question itself asked to Design a Band Pass Filter Properties: Lower -3db cutoff-frequency 500Hz Higher -...
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110 views

Equivalent model of my (real) transformer

I have created a transformer using a small cylinder (a tube) made of ferrite. The primary coil has \$N_{1}=5\$ turns of coil wire, while the secondary \$N_{2}=50\$ turns. According to a recent ...
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75 views

Equivalent circuit of a simple transformer?

EDIT: My question is: How can you translate the first circuit into one that uses simple (linear) electrical elements and, as a result, can be solved using mostly Kirchhoff's laws? I am trying to ...
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59 views

Noisy output on active bandpass filter PCB Design

I'm trying to design a 40dB active bandpass filter with a centre frequency of 130KHz and a passband of 80KHz. I don't really know much about filter design so I used the TI filter design tool to design ...
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sallen-key bpf giving low gain after coupled to differential input

I designed a Sallen-key band pass filter where the gain at center frequency is 45.6dB. After feeding it with a sine wave at the center frequency, it amplifies the signal by 45.6dB. However, after ...
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190 views

How does the formula for calculating Low and High Frequency in a Band-pass Filter occur?

Our professor told us that we should use the formulas below to calculate the F-high and F-low frequencies that our band-pass filter should have. $$F_\text{low}=\frac1{2π\,R_1\:C_1}$$ and $$F_\text{...
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843 views

Differential filters: high pass, low pass, band pass

I am looking to use a band pass filter in an EMG circuit design using the differential signals you receive from an op amp (differential/instrumentation). I have been looking for what is the proper way ...
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47 views

Is there a configuration where a circuit acts as Bandpass filter in one direction and Bandstop in other?

I am not an expert in electronics. Hence, I am looking for a broad conceptual answer. Is it possible to a directional Bandpass/Bandstop filter i.e. Bandpass in one port and Bandstop in another.
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297 views

What are the differences between active bandpass filter topologies?

I want to use a narrow band active bandpass filter but I found generally 2 topologies as seen below. What are the differences between them?
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241 views

Transfer Function Derivation

Where did the following transfer function come from? \$H(s) = -H_o\frac{\frac{\omega_o}{Q}s}{s^2 +\frac{\omega_o}{Q}s + \omega_o^2}\$ \$H_o\$ is the gain at resonant frequency. I'm told it ...
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333 views

Active band pass filter + offset

I'm trying to know the fr equation for the following op amp configuration: I have some capacitors values for specific fr frequencies: fr = 34Hz -> C = 33nF fr = 50Hz -> C = 22nF fr = 160Hz -> C = ...
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653 views

Audio Equalizer LTSpice Simulation

First, I'd like to say i'm not experienced on circuits, but i'm doing my best to learn. I'm trying to create an audio equalizer which is capable of amplifying low frequencies (20Hz-200Hz), mid ...
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286 views

Construction of a Band reject filter

I'm trying to construct something like the band reject filter on the bode graph below. I know that I could make this by using four different filters and adding them up (low pass filter + high ...
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102 views

Adjusting the gain on a 4th Order Butterworth Bandpass fIlter gain

I designed a bandpass filter with the TI filter designer tool but I initially designed with a gain of 40 dB. However, I'd like to reduce the gain to 20dB but I'm having issues doing trying to figure ...
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Designing an audio amplifier, problems with bandpass filter

I am trying to build a Audio amplifier for a university project, I think that most of my circuit is done but I have an issue with my filter as my sine signal is not symmetrical after filtering to ...
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507 views

Band pass filter bandwidth problem

I am trying to design a band pass filter that allows frequencies between 16,384Hz and 32,768Hz. Firstly I tried to make it using a passive RC band pass filter: Using the formula fc = 1/2πRC, the ...
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154 views

How to calculate cutoff freqeuncy of Bandpass filter, given an attenuation dB level (OTHER THAN -3DB)

I know that -3dB is the accepted standard, where the power of the signal is at 50%, and that upper and lower cutoff frequencies are calculated with regards to this value, and there are simple formulas ...
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74 views

Why is the input reflection signal very weak?

I built a PCB filter in Class "Band-pass" with center frequency of 2.4 GHz. The board has two SMA's (input 1 & output 2). S(1,2) looks like this: The frequency is good, However, the attenuation ...
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196 views

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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255 views

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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205 views

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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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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119 views

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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627 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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211 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 ...