A filter modifies signals based on their frequency.

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Analytical design of bandpass filter: MATLAB function documentation

I am trying to "design" a blackbox bandpass filter (butterworth or chebyshev) based on parameters such as \$f_{min}\$, \$f_{max}\$, bandwidth(BW)/Q-factor, and etc, using Visual Basic. However I am ...
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51 views

Why does this State-Variable low pass filter overheat when turning up resonance?

I am trying to build an audio-frequency state-variable resonant filter. Power supply is ±15V. The circuit contains three TL072 op-amps and three LM13700 OTAs. It receives audio input from -2.5V to ...
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1answer
33 views

Electret microphone filtering

I am coupling an electret microphone to the input of an audio codec which does all the amplification, so all I need is biasing and filtering. I picked up the circuit from a colleague and I'm having ...
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2answers
67 views

Phase Shifter: why is simple RC circuit's output 0 when phase is 90 deg?

I am rereading an electronics book (Fundamentals of Electric Circuits; Alexander) that says that the circuits or have the total impedance Z = R + jXc and that the phase shift is given by ...
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2answers
36 views

Why would an 8-order LPF switched capacitor has a least steep roll-off curve (max7405)?

As far for my understanding, a higher order LPF will have a steeper roll-off curve. Something like below would happen if we increase the number of order for the LPF: Normal LPF frequency response ...
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1answer
30 views

How to calculate the oscillator capacitor value for a switched capacitor (MAX7405)?

I would like to use an 8-order LPF switched capacitor: MAX7405 datasheet The cut-off frequency can be set by simply connecting an external oscillator capacitor, Cosc. I would like to design a 50Hz ...
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1answer
50 views

Why is the cut summed in a graphic equalizer?

I would think a basic graphic equalizer could function as such: a bank of filters, each with their own connection through a potentiometer to a summer (such as an op-amp summer). However, I've run ...
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3answers
37 views

Need help deriving cutoff frequency of output (collector) RC network

According to the book I'm studying, the cutoff frequency for this circuit is given by $$f_c=\frac{1}{2\pi(R_C+R_L)C_3}.$$ I tried to derive it by solving for the frequency at which \$V_{out}\$ is ...
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24 views

EMC/ Mains line filtering

I have an application which uses a PCB to control a big AC fan (approx 1300VA) and a cartridge heating element. Since the application will be operated on regular mains, there needs to be some form of ...
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3answers
63 views

Op Amp : Gain Bandwidth Product and LP Filter

What will happen if I use an op amp as a buffer amplifier for signals with frequency greater than Gain Bandwidth Product. More specifically : 1) Say I have a signal with 2 frequencies : a) 2 MHz and ...
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111 views

Switched capacitors using MOSFETs in filter design

I'm designing a State Variable Filter design using switched capacitors to control cut-off and resonance. Simulating this using idealized switches yields excellent results. See attached schematic ...
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2answers
72 views

Differential filter design

simulate this circuit – Schematic created using CircuitLab I have faced a problem in understanding, the following circuit. But after deep search, I expect to be Differential Low Pass ...
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59 views

State Variable Filter analysis

I'm in the process of making my own adaptation of the classic State Variable Filter (SVF) in the analog domain. Reading up on this article. I discovered that they use superposition to get the ...
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1answer
36 views

Bandpass Filter Balanced Ports?

I have a question regarding bandpass filter. What is unbalanced port and balanced ports? I noticed that outputs of balanced ports are connected to RF_P / RF_N of Zigbee IC. What are RF_P / RF_N?
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1answer
76 views

What signal will come in?

I have a simple setup as shown, I would like to know what kind of RF signal will come in? Since the filter is configured around 2.4GHz, will all ISM (WiFi, Bluetooth, Zigbee, etc.) come in? The ...
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3answers
93 views

Active Band Pass Filter Design

I'm repairing some instrumentation equipment and I've come across a filter I do not fully understand. It seems to be a band pass filter and the only documentation that came with this device was an old ...
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1answer
93 views

Switch mode power supply connected to the diesel generator makes bad voltage oscillation

GEKO diesel generator has 60 kVA electric power. Our switch mode power supply connected to this generator via passive filter DL-50EA3 and 6-pulse bridge rectifier (see the schematic). In this ...
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3answers
174 views

How to know whether the bandpass filter is stable

I am designing a bandpass filter using MFB. However, I do not know whether my filter is stable or not. Can anyone give me some criteria or methods to evaluate the stability of the filter design?(still ...
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40 views

Twin T Network to equivalent T or Pi Network

How do I convert this Twin T network to Equivalent to T or Pi network? I tried using the star delta conversion but just get confused with nodes and loops.
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1answer
178 views

Voltage drop in RC filter

There is something I'm struggling to understand about passive RC filters: When considering a simple low pass RC loop, what exactly is the gain/output at DC and low frequencies? I've been assuming two ...
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36 views

8 IR sensors and 74HC4051 multiplexer where to place low pass RC filter?

So I've got 8 IR sensors like these Then I connect them to multiplexer. And arduino will run mux's selectors through the loop.. Something about 5-10 times per second(read every sensor 5-10 times ...
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47 views

Görtzel in VHDL?

I would like to detect dtmf signals with görtzel in VHDL. I couldn't find any examples written with VHDL, would you give me some tips? Where shall I start looking for, is there already an existing one ...
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1answer
135 views

How to calculate voltage divider time constant?

A cheap and easy way of interfacing a 5V device with a 3.3V device is to use a simple voltage divider. I've read using a voltage divider to convert a fast-changing signal (such as serial lines) can ...
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2answers
35 views

Guitar Tube Amp RC Filter frequency fluctuation

In a simple LP or HP RC filter, is there a scenario where the centering frequency can fluctuate? So say the filter is a low pass and its set to pass everything up to 800hz, is there a situation where ...
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1answer
105 views

How can I keep my sinusoid in phase with its input after filtering?

A section of a circuit I'm working with makes a sinusoid from a square wave by passing it through an 8th order filter (MAX293). Up until now, everything was ok, but I was told recently that the input ...
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89 views

RC Low pass filter [closed]

I have a question in my EC subject like: Assuming there is a series RC circuit connected to a sinusoidal voltage source with a peak-to-peak value of 8V & frequency of 10kHz and a DC offset of 2V, ...
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98 views

Why does my Inductor Get Warm? (Inverter Output Filter)

I have a H-Bridge based Inverter that modulates a 350VDC source into 220V RMS @ 50 Hz. Right now I'm working at just 70VDC but my output inductor is getting quite warm. Here is a schematic: The ...
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78 views

LM13700 OTA VCF resonance

I built a variable state VCF from Ray Wilson's book on analog synths. It works well except the resonance: turning it up should yield oscillation, instead it just doubles the gain of the output signal ...
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1answer
292 views

-3dB on filters, just approximated?

I have been told that -3dB is when you get half the power or equivalently the original voltage divided by the square root of 2. Nonetheless, doing the calculations I get 3.01029dB. I figure this is ...
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138 views

High pass filter seems not to work

I have designed this basic RC high pass filter circuit in LtSpice IV: It should have cutoff frequency around 10 kHz. When I perform the ac small signal analysis the output is as expected. But if ...
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369 views

Why should I use digital filters for bandpassing rather than simply manipulate signals in frequency domain and then recover them into time domain?

I'm quite a novice for signal processing and I know this question may be too broad. But I would still like to hear hints from experts. I was taught to use butter ...
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2answers
94 views

Reducing jitter and improving speed of accelerometer output

I'm not sure if this is an EE question or a StackExchange question due to the programming involved, but anyway here goes: I just built a tilt sensor for my tractor's front loader. I wanted something ...
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3answers
80 views

Circuit analysis of active LP-filter with 2 OP amps

So this is our diagram: We want to find C1, C2, R1, R2 so that our frequency cut-off is 1kHz. We also need to have R2C2 = 2 * R1C1. So, my first instinct is to: Use KCL nodal analysis Set C1 ...
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206 views

Converting Inverter Output from Square Wave to Sin Wave

I bought a UPS, it has output of 220v AC, the problem is the output is square-wave, which causes distortion on TV/LCD, is there circuit that can take this Square-Wave as input, and output Sin-Wave? ...
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213 views

Why is Direct Form 2 (Digital Filters) equivalent to Direct Form 1

According to Wikipedia : The alternate Direct Form II only needs N delay units, where N is the order of the filter – potentially half as much as Direct Form I. This structure is obtained by reversing ...
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45 views

Is the frequency cut-off the same for these two AC coupled circuit?

I have drawn two circuits that I believe behave similar. Do they both have the same cut-off frequency? Is there any pro/cons of the two circuits, except the one is inverting and the other is not? ...
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78 views

Confusion over binary radix usage and formatting through FIR filter (and circuits in general)

Im having a bit of a hard time trying to get my head around binary radix's. Specifically when it comes to use them in a circuit. On their own I can understand them fine. For example, 2s compliment, ...
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199 views

Time delay: digital low pass filter VS analog low pass filter

I am new on digital filter, hopefully I can get some intuitive insights here. So, here is the question: A low pass filter with 5Hz cut-off frequency is to be designed. The signals presented have ...
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3answers
201 views

SNR improvement from placing analog filter ahead of digital filter

We have designed a PCB containing a data collection circuit for a customer, and their external expert presents this "helpful suggestion": Question about signal averaging vs. longer integration ...
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2answers
99 views

Does slew rate of an op-amp affect a low pass filter?

Lets say we have an active low pass filter with an OP-AMP. Does slew rate of this op-amp affect the filter? what will change? From what I understand, since the op-amp is charging and unchanging the ...
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70 views

Interface two Ethernet (10 Base) devices without 4 twisted pairs cable (Common ethernet cable) and 10 Base-T Filter

I'm autumn and recently working on a project that wants to connect two IC with part: ENC28J60 (that connects microcontrollers (with SPI interface) to Ethernet and LAN Networks) directly in a PCB board ...
2
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1answer
86 views

Light Organ — Need help with LED grid

I'm building a light organ for a school project. I've got a crossover to separate the frequencies, now I need to make an LED grid. The input will be an constantly changing analog signal (whose ...
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77 views

Demanding design on bandpass filter/ Notch filter with gain

I have posted a related question before, which can be found here: Very low noise high pass filter design However, since a different stage is to be considered, I started this new post. We are not ...
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26 views

Microstrip lines- 50 ohm line for designing filter at 3.6 GHz [duplicate]

I have a question regarding microstrip lines... why do we use 50 ohm line as a standard?? please answer and attach necessary links. Thanks
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2answers
107 views

why does passive RC filter create THD?

I am trying to make a fourth order passive RC low pass filter. I simulate it in Multisim but find that the filter creates THD. And the higher the order of the filter, the larger the THD. I can`t ...
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1answer
262 views

designing LC filter for linearizing PWM output

I have designed an h-bridge to run a TEC element. The circuit outputs output current is 4A output voltage is 4V Runs on PWM with frequency 5kHz Load resistance is 75Ω I wanted to linearize the ...
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74 views

Need comments on low noise band-pass filter design

I am a beginner in filter design. This is the bandpass filter and its central frequency is 2kHz. Would you please give me some comments on this design?
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Why too many capacitors in parallel for Vdd supply net? Can't we just add all to replace with one big capacitor?

I have given the image of Basys-2 board's power regulator IC and filters connected to it in schematic. This is just an example but this is pretty much a similar filtering design for most of the supply ...
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4answers
256 views

Very low noise high pass filter design

We are trying to design a high pass filter, which mainly goals are: very low noise. Low noise is the first concern. suppresses 1kHz by around 50dB and passes 2kHz. Gets rid of DC Dont care on other ...
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116 views

100kHz active filter design

I am designing a basic 100kHz active bandpass filter using opamps (LF353). I am only interested in receiving the 100kHz frequency (might drift a few kHz) from my input signal. I have used a basic ...