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Questions tagged [filter]

A filter selectively processes input signals in frequency- or time-domain.

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Second order stable filter for RLC circuit

I have the above circuit which is described by the following differential equation: \${d^2y / dt^2+1/RC*dy/dt = 1/RC*du_1/dt + 1/RC*du_2/dt + 1/LC*u_2} \$ where \$y=V_c\$. What I want to is to ...
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Created this Filter Amplifier Circuit; How do I connect this load while maximizing gain?

*Filter Circuit on Left, Load on Right. To give some background, that load is supposed to replicate a long 12V power line (with other stuff on it) on which we will be sending AC signals on. The gain ...
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1answer
43 views

RLC bandpass filter

I am working on a circuit: simulate this circuit – Schematic created using CircuitLab My goal is to find \$ \omega_0, \beta, \$ and \$\varrho \$ The way I approached this problem was to ...
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High order Filters (\$\ge\$2nd order) Explanation

I am not understanding the outcome I have been getting with High order filters. It doesn't make sense to me. Ill explain it in cases and where I don't understand something. Case 1: R1 = R2 = 5.6 ...
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3answers
156 views

How is this a High Pass filter?

Might be a dumb question, but isn't this a Low Pass filter? If not can someone explain me how it is a High Pass filter? This is the link for the complete document: http://www.circuitbasics.com/design-...
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1answer
33 views

Q: Amplifier's Output filter not having the Correct Cut off frequency

I am trying to design a output filter, a simply one (First order) just to play around with and for some reason when I run the simulation of it its not the correct Cut off frequency which it was ...
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1answer
51 views

What are the practical problems for designing low freq. chokes or EMI filters

The power line filters like commercial RFI or EMI filters usually composed of R L and C passive components and they don't usually work below under kHz frequencies. What makes it difficult or a ...
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1answer
70 views

How to get 50 Hz sine wave from inverter bridge driving PWM pins of MCU

I am using this circuit to see the sine wave coming from a DsPIC Pins to check the shape of sine wave created from my sine table. PWM frequency is 18 kHz But the sine wave does not seem to be ...
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4answers
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Why are there so many vias on this board?

I was looking at the MMZ09312BT1 development board layout, and I was curious about all the holes they have on the board. Are these vias? What is their purpose (I heard somewhere that they are meant as ...
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1answer
34 views

How to bias(voltage offset) unity gain buffer

First post so sorry for any bad formatting. I'm trying to figure out how to bias my signal going through a non-inverting op amp with a gain of 1. Because I want a gain one just 1, it would just be a ...
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2answers
50 views

Bode Phase Plot of RC High-Pass Filter

I have been trying to understand Bode Phase Plot of RC High pass filter. I know that from my engineering that voltage lags behind the current passing through the ...
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0answers
26 views

Relay Contact noise Filtering

I am trying to filter relay contact noise when the relay contact goes from normally open to closed. The relay part# 833H-1C-C-12VDC.The relay contacts are made out of Silver Tin Oxide AgSnO2 I am ...
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1answer
50 views

VHDL unranged integer input ports bad practice?

I'm designing a customizeable interpolation filter and I'm looking for the best way to pass the coefficients (rather supporting points) to the filter. Below you see the current implementation. ...
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2answers
50 views

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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1answer
56 views

Lowpass Filter and Attenuator

I am designing a circuit to power a brushed DC motor. The motor will be given 24VDC, modulated with PWM. I would like to have an analog voltage sense capability for use with my Atmel ATmega328P @ 3.3 ...
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2answers
99 views

Simulating and Building a Multiple Feedback Band-Pass Filter

I have a distorted signal, and only want to allow frequencies between 95kHz and 105kHz. The input voltage is at 300mV peak to peak. Thus, I need a Pass Band of 10kHz and a Central Frequency at 100kHz....
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1answer
104 views

Can a Single Supply Powered Op-Amp Handle Negative Input Voltage?

I have an input sine wave at 300mV peak to peak. I want to filter this sine wave to eliminate noise and distortion. I am planning to use the LMx58-N op-amp family, powered using a single supply: 3V ...
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2answers
58 views

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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23 views

Is the use of this IEC filter proper for the this application?

Here is the IEC module which has filters. The question is about using the IEC filter on the very left side in the below Figure. Below from left to right there will be a power flow. Right after the ...
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18 views

Rate matching in LTE or NB-IOT

I understand well the use and function and implementation of Viterbi decoder, but what is the function of rate matching block ?
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2answers
124 views

High Pass Filter Design from Transfer Function

I need to design a circuit that implements the following transfer function: \$G(s)= G\frac{s+z}{s+p}\$ where, G = gain, p = pole and z = zero.
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0answers
51 views

FFT and filtering

I'm trying to simulate a square waveform passing a bandpass filter using LTspice. Something unexpected showed up on simulation and I need some help on explanation. When I used a square 5V input, my ...
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1answer
32 views

Measuring pulsating current using current sensor

I am measuring the current of the ignition coil using the hall effect sensor(ACS712)Datasheet. But the output of the hall effect sensor is pulsed analog signal. At zero current the output voltage is 2....
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1answer
68 views

Placement of feedback line on DC DC converter, before or after cap? (and dropout problem with LT8390)

I am using an LT8390 DC to DC converter, I have a highly inductive load and it is causing dips. The dips are shown here (and about a 6V drop for 7ms): I need to get rid of the dips, which I will ...
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0answers
47 views

Using an active bandpass on a very small signal

I am trying to design a active bandpass filter for an electret microphone (the output will then be read through a microcontroller to control some LEDs) (Image source - Electronics Tutorials) I want ...
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2answers
75 views

What is Log-Domain Filtering?

Reading the report here, they use 'Log-Domain Integration'. It is said to be a type of 'Log-Domain' Filter, but googling it, there is just a bunch of reports/articles on it. Can anyone explain what ...
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1answer
82 views

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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0answers
36 views

System requirement in frequency domain

Hi Can any one help understanding and interpreting figure 6a and 6b (page 6) in the paper attached down bellow : I need to identify first the transfer function of each plot and then interpret system ...
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3answers
136 views

Inverting OpAmp with voltage divider in feedback loop

Last week I was looking for a programmable gain amplifier (PGA) with high gains (> 100V/V) and low noise. As far as I know most of the PGA integrated circuits out there are just (inverting) amplifier ...
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1answer
68 views

Detect phone call termination

I am designing an automated telephone circuit that will work with the PSTN line. I already had a question to detect the incoming ring signal. Now I want to detect whether the opponent person in the ...
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2answers
50 views

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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0answers
46 views

Digitally selectable filter for the ST7580 [duplicate]

For the ST7580, it uses PSK or FSK to send a signal over power lines. In the design guide the example is designed for an FSK or PSK signal to be transmitted at 80 kHz see page 23 for reference to the ...
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2answers
91 views

What is the application of capacitor between Vcc and GND [duplicate]

This is a schematic mo ATmega328P used circuit. It has paralleled two 100nF capacitors between Vcc and GND. (C8 and C9) What is the function of this two capacitors and why they are paralleled?
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1answer
21 views

SAW Filter input power restriction

I have front end module (915MHz freq band) in circuit Which is having 30dBm output power. Between This FEM and antenna I have to insert filtering circuit. I came across few SAW filters from Murata, ...
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47 views

Low pass filter: Robustness and time constant

It is known that the transfer function of a low pass filter is given by \$ F(s) = \frac{1}{1+ \lambda s} \$. It was mentioned in a lot of places that Increasing \$\lambda\$ increases the time ...
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2answers
77 views

Is there a circuit that can create dispersion?

I'm wondering if there's a circuit that would create dispersion effects. Essentially, I'd like to create a circuit which can do the following: Spread out a high frequency pulse. For example, put in a ...
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4answers
868 views

Detect ring signal using a low pass filter

I created 2 boards communicating each other like an intercom system. One of them has a button to send a ring signal to the other. The ring signal consists of PWM signals created by an MCU. I want to ...
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0answers
54 views

Distortion from high pass filter

I've got a big problem. And it's very URGENT(it's the project for my exam). I need a high pass filter at the output of a differential amplifier that cuts off the DC voltage of this stage. So I ...
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1answer
41 views

Datasheet Notation for Filter Parameters

I've been reading through the LTC1264-High Speed Quad Universal Filter Building Block datasheet but I'm having some trouble deciphering the meaning of some of the variables used in the equations for ...
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1answer
62 views

loop gain, open loop gain of op amp in inverting configuration (feedback capacitor)

I was trying to understand the 2nd answer from this post here, with the circuit of the post shown below. The 2nd answer has equations including open loop gain I wasn't able to understand (1st ...
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1answer
48 views

Is there an analog circuit or filter that can produce constant phase shift over a specific bandwidth?

I need to match the phase of two signals coming from a pair of transducers over the 10Hz to 4 KHz range, the difference between the two transducers is really close, however one of the transducer lags ...
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1answer
42 views

If you were to add “DC offset” with a clamp, can you easily remove it afterwards?

I don't have a circuit right now, but let's say you wanted to add DC offset to a signal (ex. to prepare a signal for an Op amp stage) but then afterwards center that signal on 0v. Is this possible ...
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1answer
60 views

What's this amplifier filter configuration?

I've come across an audio amplifier circuit that contains this following configuration: I recognize R1,C1, and R3 to be part of a first order high pass filter, but I'm not sure what C2 and R2 are for....
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43 views

How to change signal from 16,7 - 22,1 V to 0 - 3V and clamp for adc

A device that I want to extend and am reverse engineering uses two wires for power, 2-way digital communication and 2-way analog speech (say mainly 50 - 300 Hz). I haven't yet worked out all of the ...
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1answer
34 views

Filtering Audio Signals in MATLAB

I'm trying to apply a filter to an audio signal in MATLAB and having some trouble processing it. So far, I have a transfer function that describes a K-weighted filter, and I am able to create a bode ...
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1answer
84 views

Sallen-Key filter for PT100 RTD measurement

I am going to build temperature sensing system using PT100 sensor (and later Raspberry PI 3). I refer my work to Microchip note AN687 Precision Temperature-Sensing With RTD Circuits. On the page 4 is ...
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1answer
28 views

Current waveform in Class B amplifier

For a class B amplifier which has a LC filter at the output, gives Pure sinusoidal Voltage and current waveforms. But if we check back the waveform at Drain, waveform for drain current remains clipped ...
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1answer
83 views

How to calculate voltage ripple in a BLDC filter module?

Hi I need some calculation for my thesis. A found this picture on the internet. My project is almost the same. It's a pi filter for a 3 phase BLDC. The peak current is 60A. It runs from 12V car ...
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1answer
57 views

Non inverting amplifier oscillations [closed]

The point of this circuit is to take a 300 to 400 kHz 5Vpp square wave signal and convert in to a sinewave of the same frequency amplified with a gain of 2. The filtering before the op amp seems to ...
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1answer
76 views

What kind of filtering does this op-amp perform?

I am using a heart rate sensor whose schematic is provided here. The circuit uses an operational amplifier (towards the right of the figure) which among other things, does a filtering operation. I ...