Questions tagged [low-pass]

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

Filter by
Sorted by
Tagged with
0
votes
1answer
24 views

What does 'succeeds' and 'precedes' symbols mean in design of a peak detector circuit?

I am looking into the design of a peak detector circuit for demodulating an amplitude modulated wave. The circuit is a diode 'detector' connected to a low-pass RC filter. I have been given the ...
0
votes
2answers
22 views

Overall Q of a fourth order LPF and higher order LPF cascaded

If I end up cascading low pass filters to derive higher order filters, how should i calculate the Q of the overall filter? For example if i have the following transfer function $$ H(s)=\frac{1}{(s^2 +...
0
votes
3answers
83 views

Modelling a low-pass filter on LTSpice to filter an input square wave at 50kHz to obtain a sinusoidal output at 50Hz

I'm trying to create a filter that filters the output of an inverter at 50kHz PWM (from reading the comments, I'm not sure if I should be calling this the switching freq?) to a sinusoidal one at 50Hz ...
0
votes
0answers
18 views

Given a constant R,C, and the input voltage at any time, what is the output of a low pass rc circuit?

In other words, what is the transient response Vo(t) of any arbitrary input signal for a continuous voltage input Vi(t) for a low pass filter? We can make some assumptions: A for any given Vo(t), ...
0
votes
2answers
45 views

Plotting a bode gain plot with the slope in Excel

I am not an expert in Excel, and therefore, I want to know if there is a way of including the slope (dB/decade) in a bode gain plot in Excel or any free software (that allows to first input the ...
1
vote
2answers
45 views

How do I calculate the DC output of this specific low pass filter?

Hi! I am having some trouble understanding how to calculate the DC output of this low pass filter. Also are my calculations correcet that the transfer function of the filter is: $$\frac{R_{\text{8}}*...
0
votes
2answers
71 views

Help deriving the transfer function of an LC circuit?

I have the LC circuit below. I believe (but I'm not certain) that this is a 3rd order filter. Since there are two capacitors and 1 inductor. The circuit is a passive low pass pi filter. The ...
1
vote
5answers
108 views

Why are the theoretical and measured frequency responses off a low pass filter different?

The calculated/theoretical value for the cutoff frequency was different to the measured. What is the reasoning behind this other than measurement errors? It should be noted that this was a simple ...
1
vote
3answers
37 views

Demodulation/filtering of a binary signal

I'm simulating an amplitude modulation system on Matlab and have got to filtering the demodulated system. The original data to be sent was a 1x100 set of binary data. Which was then applied to a ...
1
vote
2answers
41 views

How to find the cutoff frequency using Simulink (from the scope)?

R=1000 ohm C=0.1uF I need to find the cutoff frequency from the scope and to show it matches the theory \$f= \frac{1}{2pi*RC}\$ In this case it's 1591Hz. How do I measure it?
0
votes
1answer
27 views

Help deriving a 2-port representation of an RC filter circuit?

I have the circuit below. Its a basic RC filter circuit with source impedance 50Ω from a signal generator, and load impedance 1MΩ||20pF from an oscilloscope at the output. The input voltage V2 is a ...
0
votes
1answer
45 views

What does 'passband phase' and 'stopband phase' mean?

I've been provided with a Bode plot for an RC filter circuit with a cutoff frequency of 10kHz. Im asked to find the stopband and passband phase from the graph. I'm confused how these can be just a ...
2
votes
2answers
77 views

Is there any module that controls power supply with variable voltage by PWM input? [closed]

I am stuck for a few days already at finding a solution for controlling a motor. We can easily find a motor or LED on the market. However, those modules for motors do not have a built-in regulator as ...
1
vote
0answers
37 views

Single ended to differential driver low-pass filter

I am taking a single-ended source, using a SN75ALS191 driver to convert it to a differential signal. This differential signal will travel over twisted pair cabling several hundred feet, to a single ...
1
vote
2answers
83 views

Attenuation - two stage RC low‐pass filter

I am having trouble with finding the attenuation and bode diagrams for this circuit below. This circuit is two stage RC low-pass filters. I have been trying to find resources on how to do them with ...
0
votes
1answer
28 views

Find the output for the series (RC) low pass filter

How can I solve this problem? Sorry if it is too simple but I learn from home due to COVID-19 and can not get in touch with my teachers
0
votes
1answer
44 views

RC Laplace and time domain

Another basic question to understand. It is well known that the transfer function of a low pass RC filter in Laplace domain is \$V_o(s)/V_i(s)=1/(1+sRC)\$. Now sticking to this format and taking ...
2
votes
3answers
223 views

How to calculate phase shift of a low-pass filter's output?

I'm simulating a basic low-pass RC filter in Proteus, and I need to find the phase shift of the output at varying frequencies. I've plotted a frequency response graph which shows the phase against ...
2
votes
0answers
38 views

Strange leak problem in simple tone control circuit

I built the following circuit (physically): V1 is my audio signal and the circuit is a simple tone and volume control. When both the volume and the tone pot are turned all the way down (so each wiper ...
0
votes
1answer
44 views

Low pass filter vs integrator

Context: I am programming a flight controller for an autonomous drone. I want it to be able to hover in place so I am working on a PID controller for the throttle to keep vertical velocity at 0. (...
0
votes
1answer
37 views

Dielectric absorption in capacitor (audio crossover)

I want to understand the selection of a proper capacitor type for a simple audio crossover (passive lowpass filter before woofer, passive highpass filter before the tweeter). Various blogs more or ...
0
votes
2answers
53 views

Can a differential ADC's low pass RC filter be simplified to use less components

I am making a circuit using an ADS1115 analog to digital converter to read an AC signal using the differential mode of the IC, the datasheet recommends that I add a low - pass RC filter: Can the ...
0
votes
2answers
59 views

Low pass filter offset voltage question. LM358, INA129

I am designing a low-pass anti aliasing filter. I have set my cutoff frequency to be at 500Hz, and my sampling frequency at 1000Hz, but I'm not that far yet. I designed a 4th order butterworth low-...
2
votes
2answers
57 views

How to calculate RC (in 2st RC lpf) that satisfies fc in real circuit

I'm designing a two-stage RC LPF (Low-Pass Filter) and I want a cutoff frequency \$f_c=1000\mathrm{Hz}\$. So, I choose \$R_1=3\mathrm{k\Omega}, R_2=33\mathrm{k\Omega}, C_1=4.7\mathrm{nF}, C_2=47\...
0
votes
1answer
57 views

Series first Vs Shunt First Filter Design

Im reading Practical Electronics for Inventors by Paul Scherz and Simon Monk and it says that when designing a LPF Butterworth (passive), when the output impedance seen by the filter is greater than ...
1
vote
1answer
55 views

Weird RC time constants for possible debouncing

I am modifying a CTK-450 keyboard (manufactured by CASIO) into a MIDI controller. Going over the schematics, I found the way the keyboard CPU reads the keystates, which is rather simple. They are ...
0
votes
3answers
136 views

How to choose R and C to reduce noise on analog input of arduino?

I'm not terribly proficient when it comes to hardware, so please bear with me. I've tried to google around to figure out how to choose values for a low pass filter to reduce noise on a potentiometer. ...
0
votes
0answers
28 views

Fitting to attenuation and phase shift curves for a low-pass and high-pass filter?

I'm sure this is something super basic, but I'm struggling a lot. I did a lab for my circuits class where we took a low-pass filter and high-pass filter circuit, and we recorded the input/output ...
2
votes
3answers
145 views

Why does the capacitor need to be small in RC filter circuits?

Hi there, in this example, it mentions that "One should choose R2 to be as close to 100kohm (to make the C2 small)". My question is: what are the reasons for C2 to be small? Other than the fact that ...
0
votes
1answer
70 views

how to design a low pass filter for square waveform

I have square wave signal of 100KHz with few high frequency ringing from 555 timer.when i tried to use a 100KHz first order rc low pass filter,i got a sawtooth waveform because the 100KHz square will ...
8
votes
6answers
2k views

Decoupling Capacitors: What happens to the DC on the cap once noise is introduced and it shorts?

simulate this circuit – Schematic created using CircuitLab I've been using decoupling caps for a while now and I understand their purpose in keeping DC signals clean since capacitors allow high ...
0
votes
3answers
234 views

Differences between 2nd order low pass filters

I don’t know how to design filters, but I need a second order low pass filter. I searched them on the internet and found two schemes. One is Sallen-Key, and the other I don’t know what is called. ...
0
votes
1answer
62 views

Determining values to convert square wave to sine wave at low frequency

For a project I am working on, I have a 1Hz square wave coming from a real time clock, and need to convert it into a sinusoidal wave to pulse LEDs. After some googling and playing around with ...
0
votes
2answers
218 views

Low pass filter not working properly

This is the pass band that I'm using to filter some EMG signals through electrodes. When I test it with multisim it works really well as you can see, but when I test it with real equipment (...
2
votes
2answers
222 views

How does a RC Lowpass filter work?

So I've been trying to understand how an RC lowpass filter works, and I think I got it, but I just need some clarification. My understanding: So an RC Lowpass filter in a nutshell is just a voltage ...
0
votes
0answers
25 views

adding rc filter to cheap sub

I bought a cheap computer Sub to repurpose it as a selfmade gaming vest. The circuit has 2 amplifiers on it, one for the normal unfiltered sound that goes to the 2 speakers, and then the output of ...
1
vote
1answer
83 views

Synthesizing this simple analog notch filter?

I want to synthesize this simple analog audio filter which is a notch: The inductor with resistor creates a simple one-pole low pass filter with the cutoff frequency at: fc = 1/(2pi L R) The ...
0
votes
0answers
198 views

Lowpass Audio Filter on FPGA

I am trying to establish a low-pass filter to Audio Demo code of Nexys A7 board. I have implemented a filter however I hear just a noise. If you share your time, I will be happy. I have added the ...
0
votes
1answer
48 views

How does adding a capacitor change the frequency response of this inductive LPF?

I know that a simple circuit like this in an ideal case will have a frequency response of a single pole LPF, where the cutoff frequency is given by: cutoffFreq = 1/(twoPi*L*2R) This is reviewed here....
0
votes
2answers
141 views

Low-pass cutoff frequency definition (-3dB vs. filter design)

For low-pass filters, we usually define the cutoff frequency as the frequency at which the gain drops by -3dB. Another definition, however, comes up in filter design as one of the parameters that ...
0
votes
2answers
78 views

Does any practical RC circuitry exist which will perfectly cancel out a pole?

Firstly, some basic theory…. The transfer function of a simple low pass filter is:- This transfer function has one pole. The gain goes from 1 to almost zero as frequency increases and the phase goes ...
0
votes
3answers
149 views

Design of second order low pass filter using passive RC components and opamp

I have an RC low pass filter connected to the non inverting terminal of the opamp. There is a feedback resistor from output of opamp to its inverting pin.Then an RC low pass filter is placed at the ...
0
votes
1answer
174 views

Is this transfer function impossible with a low-pass Sallen-key filter?

I was given this transfer function and instructed to use a Sallen-key cascaded with a 1st order filter to achieve it. $$H(s)=\frac{628^3}{(s+628)(s^2+628s+628^2)}$$ The first order transfer function ...
0
votes
4answers
57 views

Trouble designing a low pass filter

I was trying to design a simple 3rd order low pass filter by cascading 3 first order low pass filters along with an amplifier at the end. The transfer function is straightforward: $$ H(j\omega )=4\...
6
votes
3answers
2k views

Why is inverting op-amp behaving like a low pass filter?

can anyone explain why this circuit behaves like a low pass filter despite having no capacitor in the feedback loop?
0
votes
1answer
19 views

Configuring TI TPA6138A2 for Single-Ended PWM Inputs

I'm looking to use the TPA6138A2 to ground-center, LPF, and amplify 2 PWM inputs (between 0 and 3.3 V). My desired LPF cut-off frequency is 18 kHz and I would like to use a digital potentiometer for ...
0
votes
2answers
16 views

Should Passive LPF/HPF Component Selection Depend on Ability of Input to Source Current?

When choosing R and C for a passive LPF or HPF, should you take into account the input's ability to source current? I'm currently working on a passive HPF for an input that can supply up to 10 mA @ 3....
0
votes
0answers
23 views

Combine High and Low-pass filters to create 2-way crossover

I am in a bit of a dilemma. I was given 2 Bose tweeters (8ohm) and a Bose woofer (2ohm). They came with a build in amplifier which I want to get rid of as it makes the system unnecessarily large. I ...
0
votes
1answer
37 views

How to Cascade Filters and Audio Volume Control

I am trying to output PWM from an MCU, filter it with a LPF to form an analog signal, cascade an audio volume control that allows for smooth control between silence and a somewhat amplified signal, ...
0
votes
1answer
39 views

Choosing RC values for Active LPF to match signal input impedance

I am design a basic 1st order Active LPF with unity gain and am new to this field. How do I make sure that I choose my R and C values to match the input signal impedance or does this not matter? What ...

1
2 3 4 5
8