A low-pass filter lets lower frequencies through and blocks or reduces higher frequencies.

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The bandwidth Ω of a low-pass signal f(t) ↔ F(ω)

I'm not sure about the answers to the two parts of this question: The bandwidth Ω of a low-pass signal f(t) ↔ F(ω) is defined by the constraint: $$ \frac{1}{2\pi } \int_{- \Omega }^{\Omega } ...
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50 views

H-bridge output filtering

I'm driving A4952 motor driver with about 25khz PWM signal, with a simple coil connected as a load between OUT1 and OUT2. VBB is variable, testing with 15V but changing it doesn't alter the results. ...
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5answers
551 views

What is the purpose of this simple 1 capacitor 2 resistor high pass filter?

I have seen the standard high pass filter with the -3dB cutoff frequency = \$ 1/2\pi RC\$. simulate this circuit – Schematic created using CircuitLab However I have seen this particular ...
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1answer
85 views

For a low pass filter, derivephase of the transfer function, Vout/Vin

simulate this circuit – Schematic created using CircuitLab I have calculated the magnitude: \$ ||H(j\omega)|| = \dfrac{1}{\sqrt{1 + {(RC\omega)}^2}} \$
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2answers
101 views

Simple LP filter - calculate cutoff frequency

If I am correct to calculate cutoff frequency in this LP filter I have to sum up the impedance of resistor and capacitor, right? simulate this circuit – Schematic created using CircuitLab ...
2
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1answer
55 views

Why is this LPF design passing frequencies above resonant in such magnitudes?

It's been a while since I have worked with filtering so I decided to simulate a circuit to see what I had forgotten. I used MultiSim for my circuit simulations but will present the design using the ...
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5answers
440 views

Difference: Low Pass Filter and Large Capacitor?

When working with microcontrollers it is recommended to place filter/decoupling capacitors between a supply pin and ground. I understand the purpose of this implementation, namely that voltage across ...
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3answers
192 views

Question about RC charge-discharge curve

I found the following image on electronics-tutorials.ws: Isn't this wrong? Shouldn't the voltage rise faster during the first 2T than that it decreases during the next half period? I think so ...
2
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2answers
167 views

Dedicated digital filter

I have built a DDS (0-80MHz) with an FPGA (XC3S400) that I can program it for making almost any wave form (limited frequency by the wave form complexity). After weeks of struggling with making a ...
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213 views

Unexpected behavior of the Sallen-Key second order filter

I met an unexpected behavior when I simulated under Multisim (National Instruments) the Sallen-Key circuit given on the image below. The circuit is designed to receive a 1.8kHz modulated sin wave ...
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2answers
587 views

How to Calculate Complex Low Pass Passive RLC Filters?

I have designed a FPGA based DDS and now I want to add a low pass filter to its output. Previously I was working on a project based on AD9850 DDS(0-50MHz) and I had a commercial module for it that had ...
3
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2answers
404 views

What is the transfer function of n-cascaded RC filters?

Is there an explicit formulation for n-cascaded RC filters? The resistor and capacitor values are not necessarily same. Assume that: \$ R_i \neq R_j \$ and \$ C_i \neq C_j \$ for \$ i \neq j\$ and ...
2
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1answer
82 views

Why is there a lower limit on amplification for this filter design method?

I'm designing an active low-pass filter for a differential input. The input is on a ±100V scale and needs to be scaled down to the standard ±10V scale. I found this application note which describes ...
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2answers
93 views

how to set rc passive low-pass filter?

I have got a analog signal that include some unwanted ac noise. the noise amount is about 0.5 mv. I want to use passive rc low-pass filter but i don't understand which frequency that i need to pass. ...
0
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1answer
85 views

Confusion about filter transfer function

Today I got confused about Low pass filter transfer function. Let's assume we have a simple low pass RC filter . It is well known that at f=fc we expect -3dB (0.707) drop in Vin. Everyone knows a LPF ...
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150 views

Is this correct for non-inverting op-amp?

Do 0.1 uf and 100 k ohm act as low-pass filter in here?
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2answers
284 views

What are best values of a Low/High pass RC filter?

Cutoff frequency of a RC filer is obtained from well known equation: 1/(2 pi RC). This is one equation with 2 variables. for example R=100 , C=10 has the same result as R=10 , C=100. Which value is ...
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3answers
435 views

Why do RC circuit voltages decay *slowly* rather than instantly?

Let's take the simplest RC circuit imaginable: simulate this circuit – Schematic created using CircuitLab Now I think I properly understand why the voltage rises slowly after the leading ...
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0answers
158 views

Active low-pass butterworth filter design

I have a project on filtering out frequency above 2.5 KHz. The filter should be low pass butterworth. I am confused here as there are two cutoff frequencies I need to use. 1st cutoff freq. 1KHz and ...
0
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1answer
750 views

Arduino Motor Shield R3 Current sensing

I am trying to use current sensing functionality of Arduino Motor Shield R3, the shield is based on L289. The values that I read seem to be very noisy. I am using Arduino UNO A0 analogRead() function ...
0
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1answer
136 views

estimate SNR improvement due to filter bandwidth of low pass filter

I facing a problem in GSM simulation. I am having a perfect GMSK modulated (I can assume that GMSK filter is 200kHz or 270 kHz band limited) signal in Tx path adding AWGN of 6dB SNR (Noise 6dB below ...
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1answer
231 views

Active low pass filter giving constant output regardless of input

I have a sensor that gives me an output between 1 and 4V, and I wanted to filter out noise present on the output to give me a more stable and accurate reading. I set up an active 2nd-order ...
5
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463 views

How to recognize the type of analog filter given its topology?

Having trouble to tell what kind of filter (Low-Pass, High-Pass, Band-Pass, Band-Reject(Notch) are present given a topology in cascade. In the following picture I see 3 stages, is this ok? (2 active ...
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2answers
561 views

low pass filter design for accelerometer

I find the following code for a simple implementation of a low pass filter. #define alpha 0.1 accelX = (acceleration.x * alpha) + (accelX * (1.0 - alpha)); I have been experimenting with the value ...
2
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1answer
113 views

Filtering High Frequency Channel Noise

I have a signal that should have this theoretical shape: The signal I am receiving experimentally has the following shape: And here is a plot that better shows the shape of the waveform (I have ...
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2answers
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How do I calculate the correct resistor, capacitor for a low pass circuit?

I'm looking through an article on www.allaboutcircuits.com and www.electronics-tutorials.ws in an attempt to learn more about how low pass noise filtering on for example a circuit that needs to supply ...
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3answers
443 views

Eliminate hiss and noise

ATTiny is generating PWM based tones with 32kHz sampling rate. Then I've created R-2R DAC and then trying to amplify it for the speaker. I need to make low pass RC filter, to cut PWM hiss during ...
2
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1answer
606 views

Flash an LED to music

Im trying to flash an LED to music. I have tried to follow this article and calculate values but cannot get it to go. Basically what i think i need is: audio in through a low pass filter (isolate ...
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3answers
760 views

80's Cassette Line to Microphone Level for iPhone

This is a followup question to this one: Using an iPhone as a cassette recorder for 80's home computer I'm trying to record from an 80's home computer (a Microbee) into an iPhone. Although I ...
9
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3answers
2k views

Understanding the AVCC pin wiring on ArduinoLeonardo (low-pass filter?)

The Arduino Leonardo has an interesting difference with previous boards: the AVCC pin of the ATMEGA32U4 is connected to +5V through a MH2029-300Y ferrite beads and to GND through a 1uF capacitor. In ...
2
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2answers
229 views

Recommended placement and routing of an RC Low pass filter

What are the recommended placement and routing techniques for the following RC low pass filter circuit: I made an initial placement and routing that's shown below: Actually it's randomly placed ...
3
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1answer
539 views

Low Pass Filter Design [duplicate]

Possible Duplicate: Injecting a communication signal over DC power supply lines I have a pretty simple circuit, but I need to send an output PWM signal through the same place I'm getting my ...
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1answer
1k views

Filter Design with Opamps Query

While I was reading about filter design, and going through the schematics, the following 2 questions popped up in my mind and I could not find a satisfactory answer to them: 1) A first order low pass ...
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2answers
591 views

Design a 1 GHz lowpass filter

I want to design a 1 GHz low-pass filter. I have tried to find a COTS lowpass filter at such high frequencies but I can't find one. Hence, I have decided to design one using microstrip lines. So, ...
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829 views

100W Low Pass Filter

Currently I have a 60W amplifier for the 400-500MHZ band with a 50Ω impedance. In order to prevent jamming other frequencies I will need a low pass filter to block any frequencies above 500MHZ. I just ...
2
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2answers
1k views

How to correctly simulate this filter?

I am trying to design a low-pass filter for a 24V, DC, 10A power line to suppress EMI, RF interference and noise in a bus. There is no ground(chassis). I am trying to simulate this filter that was ...
5
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1answer
201 views

TI Application Report - What are those additional resistors in the low pass filter

I was searching some documents and tutorials online for filter design. Then I stumbled upon this TI application report. The following is referring to section 2, figure 7 and figure 8 of the paper. I ...
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3answers
447 views

Do I have a ground loop or another problem?

Okay, I know this is an electronics Q&A site, and this question is mildly computer related. But I've got this problem with my VGA monitor, a graphics card and a computer. The problem is the video ...