Questions tagged [low-pass]
A low-pass filter lets lower frequencies through and blocks or reduces higher frequencies.
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Is it good to equalize input impedances in cascade active opamp filters?
In my design, I designed a first 2nd order high pass filter with a Sallen key cut-off frequency of 0.2Hz and an input impedance of 250kohm. Then, I designed a second-order Multiple-Feedback low pass ...
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what is the purpose of the additional resistors and capacitors in the reference design of the multiple feedback fully differential low pass filter?
What is the purpose of the additional resistors and capacitors added C14 R12 R14 R13 R15 C15 in the reference design of the .second order multiple feedback fully differential low pass filter?
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Trying to power a 12 V LED underglow system using PWM signal from dome light
I've learned a lot from the brilliant minds on this forum so far, and I think I've narrowed my original question a bit.
I'm trying to create an entry light effect in my car using my LED underglow ...
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strange phase behavior RC low pass filter
I have a low pass RC filter (R=12Ohm, C = 22µF) Which is showing some strange behavior in the phase shift. The cutoff frequency is around 600Hz, as calculated.
But the phase shift goes to -45° only at ...
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Non-standard low-pass filter design
While experimenting with various low-pass filter topologies (audio application), I came up with the following design:
simulate this circuit – Schematic created using CircuitLab
It seems to ...
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Purpose of this resistor in a low-pass filter
I found this filter configuration on one of older soundcards:
simulate this circuit – Schematic created using CircuitLab
V1 here is the DAC output with a positive voltage offset.
What is the ...
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How much gain I am getting and with the 2 stage transistor amplifier attached with a Global NFB [duplicate]
This is just a direct manual solving directly subtituting values in a formula with disregard to temp etc.
Sorry for the incomplete information here are the goals of this:
"gain of 100≤Av≤130 and ...
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Is this transistor amplifier with low pass filter correct? How should I measure the gain and frequency range?
My goal is a gain of 100-130 and a frequency range of 1-10 kHz.
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Differential DAC filter capacitor options
The standard output filter for a DAC with a differential voltage output looks this way:
simulate this circuit – Schematic created using CircuitLab
However, some DACs have this filter ...
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RC-filter transfer function confusion
simulate this circuit – Schematic created using CircuitLab
I have a question about the transfer function of the above RC-lowpass filter. If I switch places of the capacitor and the resistor to ...
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Sallen-Key filter with input signal attenuation
I want to reduce input signal amplitude before it gets to the low pass filter by 6dB. I could use MFB topology for K<1, but that would invert the phase. Is there a solution that keeps the phase? ...
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Trouble understanding resulting bode plot while getting hands on filter design
Recently tried to get hands on filter design, I tried to design à simple low-pass RC filter as shown here.
simulate this circuit – Schematic created using CircuitLab
Cutoff frequency must be \$\...
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Non-constant active filter gain
I designed an amplifier using an instrumentation amplifier and an operational amplifier. Here, I used a 2 Hz high pass and 100 Hz multi feedback low pass filter, but I could not get the efficiency I ...
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Problems with output signal of a 2nd order low pass Sallen Key filter for an electret microphone
I'm having problems with a small circuit based on the amplification of a audio signal received by an electret microphone. It goes to a 2nd order Sallen Key low pass filter circuit with an ...
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LTC 2065 is not working between 2 V - 4 V power supply
I'm having a problem with the LTC2065 operational amplifier design. I use a 3.3V supply as I show in the picture, and after boosting my input signal I make it oscillate at 1.8V using a 1.8V virtual ...
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lowpass prototype to bandpass filter
Bandpass filter with a center frequency of 10 rad/sec and bandwidth of 20 rad/sec here, wo= is mentioned as geometric frequency that's why I am confused.
The solution in which picture is correct?
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Resonant circuit in class C amplifier
Questions
What is the better option when maximum efficiency of class C amplifier is needed:
LC circuit between VCC and drain of amplifier + low pass filter
RF choke and low pass filter
simulate ...
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Differential Mode EMI Filter Design for DC Power Input Noises
https://www.murata.com/en-us/products/productdata/8796777775134/ENFH0008.pdf
https://www.digikey.com/en/products/detail/murata-electronics/BNX022-01L/1825573
Hi everyone, I try to understand this ...
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Connecting low-pass filtered output of one comparator into a second comparator
I have the following situation: I have a signal with periodic, short (~2ns), ~1.5V pulses spaced ~10-20ns apart. I would like to detect when the pulses disappear, i.e. when there is no pulse for ~1us ...
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Trying to make a glorified aux splitter, but it won't work
I have a project due in a couple of months, and decided I want to make a aux splitter where you can control the volume of left and right on two inputs and get a single output, kind of like a mixing ...
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How to improve the performance of my low pass filter design
Goal:
I am designing a low-noise, 8-pole, low pass filter to use in the output stage of a lock in amplifier. The filter needs to attenuate wide-band noise and a doubled carrier frequency in the range ...
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Are RC /CR - Highpass filter the same?
I‘m quite new to electrical engineering and one of the tasks is to showcase and plot an CR high pass filter. I am familiar with RC HP filters but this is new to me. Just changing the order of the ...
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Can't derive transfer function of RC filter with load
I am trying to go along with an example on a simple RC filter with load in a book called Practical electronics for inventors.
simulate this circuit – Schematic created using CircuitLab
Although ...
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Is there a reason to use different sets of resistor values in the 2 stages of a butterworth LPF?
I needed a LPF for my design so I used Filter Design Tool from AD to generate one. The generated circuit includes 2 sets of resistors of different values, which I find inconvenient. Is there a reason ...
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Transient analysis of the low pass RC filter
I have designed a low pass RC filter and trying to simulate using transient analysis. I can't figure out the magnitude of the input and output waveform. What's the time delay between the input and ...
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Ideal Low Pass Filter shifted is still ideal Low Pass Filter?
maybe a stupid question.
But let us say we have a ideal LPF filter like this:
$$H\left(j\omega \right)=\begin{cases}1&-\omega _m<\omega <\omega _m\\ 0&else\end{cases}$$
If I shift it , ...
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Problem with analog passive lowpass filter
I designed a lC low pass filter and instead of getting a frequency response of lowpass, I got a strange frequency response as mentioned in the figure below.
Does anyone have an idea ?
The circuit:
...
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How do we get the gain and cut off frequency values of the active low-pass filter?
I'm trying to find the gain and cut off frequency values myself. But I can't get the same result when fiddling with the formula. The last screenshot is from my own solution. Where am I doing wrong?
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Why do my high and low pass filters look like high pass filters in LTSpice plot?
I am new to this and trying to learn about designing analogue audio filters. I looked at a couple of tutorials online that gave examples about how to implement and simulate high and low pass filters. ...
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2nd order active low pass filter
Apparently the voltage of the inverting input to the op-amp in the 2nd order active LPF should be equal to \$v_2\$. Would anyone be able to explain why this would be the case?
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Using the same ultrasonic transducer for Tx and Rx in distance measurement
Goal:
Measure distance to surrounding objects using 5 automotive grade
ultrasonic transducers mounted to different points on a small robot.
Requirements:
Multiplex the drive and receive pulses so ...
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Why do I a get different cut-off frequency in LTspice?
I have built a low-pass filter circuit according to the multifeedback topology using the values for the resistors and capacitors calculated with the help of this website.
According to the website, ...
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Multiple feedback design methodology
I am having trouble finding a step by step approach to the MFB filter. I came across a tutorial from Analog Devices but I am struggling to find what is the reasoning behind their equations, and can't ...
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How can I only let a specific frequency pass in an AM receiver?
I wanted to create an AM receiver and I know partly how to demodulate the signal. I know I need to use a low pass filter to get the low frequency audio signal, but I don't know how to only get data ...
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3dB Cutoff Measurement vs (Calculated + Simulated)
I am stumbling upon a very strange situation unless I did something totally wrong in my measurement setup. Speaking of it, I've installed an acoustic measurement tool (REW) and measured for testing ...
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Why is the cutoff frequency of this Butterworth low pass filter not at -3 dB?
This is a 15th order Butterworth low-pass filter. I am trying to compare the cutoff frequency in simulation graph with the one I have calculated which is 83.68 Hz.
All I know was the cutoff frequency ...
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Cut off frequency of a passive second order low pass filter
I was trying to do a simulation for second order low pass passive filter, and the equation of the cut off frequency is $$f_c=\frac{1}{2\pi\sqrt{R_1C_1R_2C_2}}$$
when I calculate it on the values of ...
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White noise percussion resonating capacitor
I'm breadboarding an analog drum module from some 70s schematics. Experimenting with noise filtering, I've achieved a cool "resonating" sound but the result is a bit too noisy for ...
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Effects of discretisation on bandwidth of low-pass filter
Consider a first order low-pass filter, with a cut-off frequency of (2π)*(8000). This filter will have a cut-off frequency at (2π)(8000), as well as a pole there.
$$
H(s) = \frac{1}{(\tau.s + 1)}
$$
...
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Adding an active low pass filter to circuit changes voltage from 2-3V (0.5v amplitude) to 'dc' 2.5v but doesn't when separate
I have circuit that contains a summing amplifier as well as other components previous to it. I am trying to add an active low pass filter to limit frequencies above 50Hz. It works perfectly on it own, ...
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How can I calculate the cut-off frequency of an RC filter?
I tred to calculate the cut-off frequency of the circuit below.
When I think of two resistors as parallel and calculate them in a built-in RC filter calculator, I found a 51.0112 Hz cut-off frequency. ...
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How is an RCD snubber different from an RC low pass filter?
The RCD snubber is used in flyback SMPS designs where AC-DC conversion is carried out. I know that a snubber circuit is used; its purpose is to filter transients. According to my understanding, the ...
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Class-D audio amplifier produces a sawtooth wave on the output, not sine
I am using a MAX9744 Class-D amplifier and want to get a sine wave in the output. Someone suggests using an LC low-pass filter for this, and in the datasheet of the amplifier, the values for inductors ...
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How to calculate the correct values of the coil and capacitor for an LC circuit and what type of capacitor to use?
I designed a complete H-bridge using four MOSFETs, to be able to control the supply voltage of a Peltier cell. I put a 1 μH coil in series with the Peltier to work as a small filter and I use an INA ...
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About PLL input frequency
I am working on a PLL design. I am at the research stage now. I am confused about the PLL input frequency range.
This frequency has to remain constant. If this input frequency stays constant, how can ...
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Calculate the formula of RC low pass filter
In RC filter, the low pass filter formula is
$$H(s) = \frac{V_\text{o}(s)}{V_\text{in}(s)} = \frac{1}{RCs + 1}$$
$$H(j\omega) = \frac{1}{j\omega RC + 1}$$
and the absolute value is
$$|H(j\omega)| = \...
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AC Op-amp integrator with DC Gain Control in LTspice
Our teacher explained to us that this set up allows us to produce the effect of a low pass filter:
I have indeed found useful formulas to achieve this.
The problem however is that when I simulate ...
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Need help with pulse sensor design modification [closed]
So I've got the below pulse sensor design. I don't understand why they filter before they amplify. I'd like to modify it in a way that I amplify the signal first, LPF second, HPF last. For some reason ...
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Delay for low-pass filter to give proper mean value of a periodic signal on LTspice
I noticed that I have a 4-5 seconds delay before the output of my low pass filter op amp gives the correct mean value of an input square wave. Is it normal for the delay to be that long and if so, are ...
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Second-order low-pass RC filter not working as expected
I am working on building a crossover filter for a set of speakers and I have started by designing a simple second-order RC low-pass filter on a breadboard.
Assuming the circuit is wired correctly (I ...
