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Questions tagged [filter]

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

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0answers
46 views

50hz notch filter attenuating at 0hz

I built a twin-t notch filter to attenuate at 50 Hz, but it attenuates at 0 Hz. Here is my circuit diagram: R3=15.1kohm R2=r1=31.0kohm c1=200uf c2=c3=100uf r4=100kohm When I gave a 1 Hz to 100 Hz ...
2
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3answers
80 views

How to add a low pass filter to this non-inverting amplifier circuit?

I've come up with this simple circuit as an amplifier before an 8bit ADC which receives audio signals. R2 is actually a variable resistor (pot.) of 100k. The circuit also biases the signal to VCC/2 ...
0
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0answers
42 views

implementing FIR filter on 20 bits data [on hold]

I am new to digital signal processing, And I am currently working with DSPIC33F. I used Matlab design Filter to extract the coefficients of the filter. My Problem is within my Data because it is ...
0
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1answer
71 views

how to reduce the amplification of second order notch filter

I build a second order notch filter.it is centered at 50hz. When I gave a sine wave signal with a sweep from 20hz to 80hz.The signal's input amplitude is 1v and the signal's output amplitude is like ...
1
vote
1answer
51 views

How to choose an inductor for a LCL filter?

I am trying to make a voltage generator. I used an inverter and it is controlled by a PWM signal. I used a LCL filter to filter the output signal since it is rich in harmonics but in the choice ...
0
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0answers
26 views

FIR Filter Transition Coefficient

Design a length L=40 linear-phase FIR filter using frequency sampling design with an optimum approach. Use the transiton coefficient table given in Proakis and Manolakis. My M is 39, how can I use ...
2
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1answer
40 views

Pi Filter Grounding for RF sampling ADC

I am working as an intern at a start up. We have got a project for Data Acquisition system in which we are using three RF sampling ADCs. ADC is ADC12DJ3200 from TI which has 6.4GSPS sampling rate ...
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0answers
16 views
1
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1answer
33 views

EMI LC pi-filter design guide [closed]

I would like to design an EMI input filter for my battery powered BLDC motor driver, but have never done anything like this except for some simulations in college I can barely even remember anymore. ...
12
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6answers
2k views

Why does increasing the sampling rate make implementing an anti-aliasing filter easier?

From an answer to a question regarding sampling rate and anti-aliasing filter I read the following: The closer you get to the theoretical minimum sample rate, the more difficult the analog filter ...
0
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1answer
36 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 ...
0
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2answers
96 views

What is the “dt” in the complementary filter equation and how do I find out the “dt”?

I am trying to implement a complementary filter in my system but I do not quite understand what "dt" means and how should I find out the "dt" in the complementary filter equation. I found the ...
0
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0answers
52 views

Selecting RC filter components for half wave rectifier

I have a circuit where Input is a Sine pulse of 40V Amplitude and the circuit is as shown: After redtifier diode , there is a RC FILTER. I have used a tantalum capacitor and 0603 resistor. I was ...
0
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0answers
39 views

220 volt ac to 12 v dc converter without voltage regulator

I want to design Additional RC Filter. My input is 220V AC and I want to observe 12 V DC output. I am designing 100 Hz with a full-wave bridge rectifier. My question how can I find the output of ...
1
vote
1answer
63 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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0answers
19 views

Attenuation factor

In A.C. Circuits if R=2k ohm and c=2 micro farad what is the frequency at which the attenuation factor A drops by 20% of its maximum value? In the attached picture my attempted to solve the question . ...
0
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1answer
61 views

Filter transfer function

I've the following filter circuit: simulate this circuit – Schematic created using CircuitLab The transfer function can be written as follows (I think): $$\frac{\frac{1}{\text{sC}}}{\frac{1}{\...
1
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0answers
33 views

How to Low-Pass PDM Output Data

I have a PDM-Mems Microphone which provides me with 101010 data, the Microphone has a Clock of 3Mhz. I read the manual about how PDM is generated, but I haven't worked with digital filters yet and in ...
0
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0answers
21 views

PSPICE Error in Second order High-Pass Sallen-Key Filter

As part of a class project, I'm trying to filter pulses with noise by implementing a High-Pass Sallen-Key Filter with the resistors replaced with transconductance amplifiers (schematic shown below). ...
2
votes
1answer
48 views

How to determine the best resistance for a weak signal Twin-T notch filter?

I am designing a 50/60 Hz Twin-T notch filter for a weak (biomedical) signal output from an instrument amplifier (InAmp) to be chained to another active low pass ...
0
votes
1answer
65 views

Calculating sampling frequency off of estimated stop band attenuation

I'm trying to calculate what I will have to set my microcontroller's ADC sampling rate at in order to sample a band of 500kHz to 1.6065MHz without aliasing. Some constraints here are that I have to ...
1
vote
4answers
128 views

Is there a preferred order in which to apply (analog) filters in a chain?

I'm working on a project where a very weak signal need to pass through a bunch of filters. However, I am seeing quite a lot of different ways in which the order of the various filter stages are ...
1
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1answer
60 views

Multiple feedback single supply

I've been trying to get a multiple feedback lowpass filter to work. With this schematic. The filter works in the simulation but when i try to build it, it gives no output. The op amp used to build ...
0
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2answers
68 views

Does this Sallen and Key filter work on a single supply and does the input offset matter?

This is the schematic for a Sallen and Key from the Doepfer Musikelektronik website: simulate this circuit – Schematic created using CircuitLab I intend to run this in a synth, the oscillators ...
0
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2answers
65 views

Can the OpAmp be safely removed from the Twin-T notch filter?

This is a very typical (text-book) example of an active Twin-T notch filter with adjustable Q. However, after having posted THIS question, one of the commenters pointed out that there is a design ...
3
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1answer
68 views

RC Frequency to Voltage Converter

I'm an electronics engineering student and I want to state that this question is not my homework, it is a tiny part of my project (PWM encoder) but I couldn't pass it. I'm trying to make a "frequency ...
0
votes
1answer
66 views

What's the conduction angle for a full wave rectifier with filter capacitor?

Shouldn't the conduction angle for a full wave rectifier with filter capacitor be twice that of a half wave rectifier with filter capacitor? The conduction angle for a half wave rectifier with filter ...
2
votes
2answers
74 views

Wrong frequency response - LTSpice

So I have this simple OP-AMP circuit that is supposed to be a low-pass filter for which I made the calculations so it passes all frequencies below 1591 Hz (approx). The values of the components are in ...
3
votes
2answers
119 views

Why use an opamp for the variable Q feedback in a Twin-T notch filter?

In the following circuit, for a Twin-T notch filter, the author is using an additional inverting op-amp for the T-filter "feedback", that is connected to a potentiometer (pot). Image credit: here ...
4
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2answers
101 views

1960's video showing early computer design & simulation of a low-pass filter circuit?

I ran across this IBM computer aided design and simulation software demonstration from the 1960's in the video The Incredible Machine (1968) The gain vs frequency plot shows what looks like the ...
0
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3answers
72 views

How to regulate a flyback transformer to have output of 100mv or 200mv ripple?

I see spellman/bertan hv power supplies achieve this but are expensive. Is there a circuit that can regulate cheap flyback transformer's voltage ripple just as well? I've seen some circuits referred ...
1
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1answer
26 views

Handling Phase Shift with ANC

I've been working on a circuit to do active noise cancellation, but I'm worried about controlling the phase. Here are my assumptions, and I'd love some help understanding 1)what of my assumptions are ...
0
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0answers
47 views

Problem with driving inductive loads with inverter

Newbie here. I've got this old line interactive type UPS which cannot drive any inductive load. I suspect the issue is with inverter side of the cct as there is no issue when the commercial supply is ...
0
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4answers
46 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 ...
1
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0answers
87 views

High pass shunt filter

I have a DC motor, which is used as an electromagnetic brake. However I want to leave certain frequencies uninhibited, so I thought this should be possible by adding a shunt filter on the DC motor ...
0
votes
1answer
38 views

Filter power supply for video signals

I'm drawing a board with an MCU (running at 32 MHz), some serials and an analog video section (mux and amplifiers). I kept the video section physically separated from the digital one: i.e. it's placed ...
0
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1answer
60 views

What is the purpose of the capacitor in this circuit?

Is the purpose of the capacitor, C1, to filter out any possible DC component that the input signal has?
1
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1answer
44 views

Differential (Subtractor) op amp with low pass filter

is it possible to have a subtractor circuit with a low pass filter in it? My thought is that I would have the possibility of doing that if I add a capacitor in parallel with R3. Is it actually ...
12
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1answer
208 views

Troubleshooting a faulty filter circuit in a PAL CRT display

I have an old CRT monitor (Phillips CM8833) which I am attempting to repair. When displaying a composite PAL signal, it only shows a black and white image, but it is still able to display RGB signals ...
1
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2answers
74 views

Discarding divergent sensor data from running average

I'm building a inductive vehicle loop detector. By measuring the frequency of a LC-oscillator where the cars will pass over the inductor of the LC-Oscillator. If the cars pass over the inductor the ...
0
votes
1answer
45 views

How to implement a dirac delta as input signal for this system

y[n] = b0x[n] +b1x[n-1] I have this MA filter in matlab as following ...
0
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4answers
41 views

Is there a standard definition of LPF stop band starting point in terms of dB attenuation

Below illustrates a LP filter bands: I can say that the transition band starts at -3dB. But the transition band ends at some point and there the stop band starts. In this example it is -70dB they ...
0
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3answers
40 views

Pulse distortion low pass filter and group delay

What is really meant by pulse distortion? I have come across several paragraphs which mentions the cause of the pulse distortion is group delay. But doesn't a LP filter still distort a pulse even ...
0
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1answer
57 views

Regards Band Pass Filter with AmpOp

I've tried to solve this contest question regards the band pass filter (find the frequency at low-pass and high-pass filters) the picture below: My attempt: I consider that the first stage is 2 low-...
0
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2answers
80 views

Why won't my IIR filter work?

I have a cascaded IIR filter that has a sampling frequency of 1kHz and consist of a highpass filter with a cutoff frequency of 0.8Hz and a lowpass filter with a cutoff frequency of 5Hz. I have ...
2
votes
2answers
196 views

Understanding the exact meaning of dB/decade in a Bode plot

To make the question clear I will ask this with an example. Let's say we have a LP filter with a -3dB attenuation at cutoff frequency of 1kHz. And lets say we are given the steepness of the filter as ...
1
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0answers
25 views

Realizing a prototype filter in ADS or any other simulator

I'm trying to design a stub-filter, and I'm stuck on realizing the filter design using Richard's transformations and Kuroda identities. I'm building a 5th order Chebyshev LP-filter for 2.6 GHz pass-...
0
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2answers
117 views

How can implement a low pass filter with this PWM signal? (Deadstop Fan won't start error)

I want to low pass the signal to the fans in this circuit. PWM frequency is 35khz and I calculated that I would need C = 10 µF and R = 10 Ω But no matter how I place my capacitor and resistor, ...
0
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1answer
38 views

Cascaded RC Bandpass filter loading problem?

So I calculated the Highpass stage output impedance to be 22kohm and the input impedance of the Lowpass stage is 430kohm when f=5khz, still in the output I am getting half of my supply voltage despite ...
4
votes
1answer
103 views

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, ...