Questions tagged [filter]

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

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93 views

What are non-reciprocal bandpass filters?

I am not an electrical engineer. I have come to know about a term called as "Non-reciprocal Bandpass filters" which seems to be useful to me. Here are some links to the papers (unfortunately ...
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3answers
419 views

How does load resistance affect RC low pass filter?

I am building a low pass filter. This is the equation I'm using to calculate what frequencies I want to pass though, but I have a couple questions on details. $$ f_c = \frac{1}{2\pi RC} $$ What goes ...
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1answer
118 views

Transfer function and characteristic equation

I have the following network (page 805, example 14.5, Agarwal & Lang, Foundations of Analog and Digital Circuits): The associated transfer function for \$i_z, v_z\$ is \$ H(s) = \frac{I_z (s)}{...
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1answer
64 views

How to take my differential filter and design it for a different frequency and impedance?

I have a board with this differential PI filter: simulate this circuit – Schematic created using CircuitLab Say it's designed to pass signals with frequency X and bandwidth B1, and now I want ...
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2answers
83 views

Is LC filter at ESC input a good idea?

A wall climbing robot's controller board distributes power to a 150W brushless suction motor, 2x 30W brushless wheel motors and precious digital electronics (Intel NUC + STM32), the latter is ...
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1answer
64 views

How would I test if my low pass filter works on a remote FPGA?

I am making an example low pass FIR filter design to go on an Intel FPGA. I have an idea about how I'll test it via simulation (by having the input be a sum of sine waves, and the cutoff frequency be ...
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1answer
84 views

Is it easy to siphon power from a powered antenna?

I have a property which is in a bit of a hole. My driveway goes up to an elevation above my house where semi-local TV signals are present. When they were still in local business, I bought a powered ...
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4answers
158 views

How to Filter Harmonics in Wideband VCOs

I have a need for a RF signal generator, but I figured it would be a fun project to design a crude one myself. The main technical challenge I'm stuck on is how to filter out the harmonic content ...
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46 views

AC LC Filter for a Solenoid - Unexpected Behavior

I've been working on a circuit that uses a microcontroller and an H-bridge with 34VDC supply to control a variety of low voltage loads including 24VAC solenoids at 50/60Hz (SHEPWM waveform to knock ...
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2answers
174 views

Band-pass filter vs. Serial Low-pass+High-pass filter - Is there a difference?

Is there a difference between a band-pass filter (BPF) and tying a low-pass filter's (LPF) output to the input of a high-pass filter (HPF)? It seems to me that they should do the same thing---or ...
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1answer
58 views

I/O panel filtering for shielded room

We are looking into setting up a very basic shielded chamber inside a small room at my company to be able to perform some basic relative radiated EMC measurements. We will buy a somewhat cheap ...
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1answer
57 views

Smooth signal using a capacitor [closed]

This is a full wave bridge rectifier I have read that if you put a capacitor parallel to the load resistor instead of DC pulsed signal we get a more smooth DC signal. However I am unable to ...
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1answer
120 views

Where do we place a Pi filter?

I have used pi filters in the past with the USB powers and it worked great. This time I need the pi filters to smooth out the 24V supply from a regular SMPS power adapter. There is a load switch/fuse ...
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1answer
48 views

RC low pass filter difference with RC high pass filter

This is a low pass filter: simulate this circuit – Schematic created using CircuitLab This a high pass filter: simulate this circuit If we add a load resistor to the high pass filter it ...
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2answers
192 views

Dipole antenna circuit diagram

I have this circuit : simulate this circuit – Schematic created using CircuitLab I am trying to build a radio and I need to build a band pass filter . How do I do that?
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1answer
28 views

Camera - Auto Night Vision “Mode” (ON only when dark)?

I am wondering how night vision "mode" could be automatically switch on & off in commercial CCTV? Something like this: https://www.youtube.com/watch?v=ilaXGtsx-DU (video demonstrate CCTV ...
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61 views

Removing output of low pass filter when turning off power

I'm constructing a presence detect circuit using a pulse modulated signal of 5 kHz and an infrared transmitter and receiver. The 5 kHz signal drives an infrared transmitter through a 3904 NPN ...
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1answer
68 views

DC filter for a spectrum analyser - cut off frequency

Most of the available spectrum snalysers do not want a DC component to their 50 ohm input. But how low should the cutoff frequency be? Also which parameters indicates that clearly in the datasheets? ...
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1answer
90 views

L-C-L vs Pi network

I am playing with a simple high-pass phase shifter implemented as a Pi network in Sonnet Lite with a center of 146MHz and discovered something by accident that I would like to understand: By mistake, ...
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2answers
75 views

Is this differential RC filter needed on a reference voltage?

What is the use of the differential RC filter at the end of this op amp (at least I'm seeing R100+R98+C28 as that)? P3_3V_REF is a reference voltage for the 4 ADCs in the TMS320F28377D-EP MCU. An ...
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1answer
163 views

How Do You find The Cutoff Frequency of a Low Pass Filter?

A lowpass filter exists around R1,R2,R3 and C2 but how would you find the cutoff frequency? I think that you have to first find the Thevenin equivalent circuit and this is what i got: RTH = (R1//R3)//...
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1answer
64 views

Butterworth and Chebyshev filter problem

Find the minimum order Butterworth lowpass filter whose attenuation isn't bigger than 2 dB at 5 rad/s and has 10 dB at 8 rad/s, 20 dB at 10 rad/s, and 40dB at 30 rad/s, then do it for Chebyshev filter....
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1answer
129 views

LTSpice provides incorrect bode plot

I want to replicate this structure in LTspice where the components 1, 3 et 4 are resistors with the same resistance R and 2 et 5 are two capacitors and opamp LT1356 this is the schema I made this ...
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30 views

Filtering Options for an RTL-SDR (DSP and Analog routes)

I have several related questions regarding filtering for an RTL-SDR radio. It's readily swamped by the very, very strong AM and FM radio stations local to me. So much so that your basic passive RC ...
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2answers
190 views

Importance of 2nd or 3rd order RC Low Pass Filter in noise/ripple filtering

I dont quite understand what importance does having a 2nd or 3rd order RC Lowpass filter do to filtering power rail noises. If the first stage filter only allows frequencies below 15.9 Hz arent the ...
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3answers
99 views

How can I overcome the distortion using in this circuit by using same products as we see in picture ? Or we can use 2n700 series, 3906 and 3904 bjts

Or we can use 2n700 series, 3906 and 3904 bjts. My aim is 10W, gain 100-1000 (adjustable), 50hz-20khz amplifier by using this basic components.
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27 views

Gradient based optimization for microwave filter design

In S. Amari's paper - Synthesis of cross-coupled resonator filters using an analytical gradient-based optimization technique(2000), for reducing a filter's unnecessary cross-couplings, the matrix \$[...
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0answers
25 views

Ripples in the passband of a SAW filter

In SAW Filters we have a phenomenon called TTE, Triple Transit Echos. How does this phenomenon render inband ripples different than in a Chebyshev filter? Am I also correct to assume that the ...
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1answer
80 views

Why does this high pass filter behaves like band-pass filter on Multisim AC Sweep simulations?

I have this high-pass filter schematic and its AC Sweep simulation. Until the break through the end, the graph is right but I can't see why the graph breaks on the right hand side and filter behaves ...
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0answers
47 views

Median Filter FPGA [duplicate]

I trying to build on my FPGA project median filter for 1-d vector, I need my median filter to be large, the Internet is full with references for 9 points median filter but didn't saw anything for ...
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4answers
250 views

Decoupling capacitors inrush current

My question relates to decoupling capacitors on power input rails. I see a lot of designs with MCU boards that use only decoupling capacitors and no chokes, beads, inductors, or resistors. Isn't this ...
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2answers
72 views

How can I calculate low and high frequency in my circuit?

How can I calculate low and high frequency in my circuit? I have used an 8-ohm speaker.
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2answers
68 views

Why is component spread a figure of merit for analog filters design?

Sometimes I read that in analog filter design, component spread is a figure of merit. The lower the better. What is the advantage (or disadvantage) of having a low (high) component spread? The only ...
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1answer
256 views

Second order differential equation implementation using OP-Amp

I am trying to implementat the following equation \begin{equation} x''+4x'+25=\sin(20t+36) \end{equation} using OP-Amp's. I tried to use state-space technique to implement it in the below circuit x ...
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0answers
114 views

27 points median filter

Edit: I successfully made it work, but the algorithm not efficient I taking the date coming in to my block, pipeline the data for how much points I need to median filter (for example 31), take all ...
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0answers
61 views

Low-pass (band-pass) filter for op amp circuit

I have a circuit that amplifies a one-shot inductive trigger pulse of about 1.3Khz (@780 micro sec period) from about 10-200mV to about 3-4V. Between C1 and R3 there is a 0.13uH inductor coil with 11 ...
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1answer
67 views

Chebyshev filter - theoretical vs simulation gain

Question is about the gain peak (or maybe more suitable would be growth) ocurring in higher frequencies (>20kHz) in Chebyshev filter 4-th order in simulation (simulated using Bode Analyzer in NI ...
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0answers
63 views

Crosstalk/Ghosting on ADC input

I have an ADC circuit which uses AD7689. The inputs of the ADC are driven by LT6010 opamp, and have a low pass filter . All 8 channels of the ADC (AD7689) have the same driving circuit. Every other ...
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1answer
44 views

Determine output filter using the bode approximation

Given that the carrier frequency Fc and modulation input frequency Fm are known, how would I use the bode approximation to determine an output filter, if the carrier frequency component must receive ...
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0answers
70 views

Problem understanding transfer functions of second order filters

The transfer function of any second order filter can be found by analyzing the circuit using the Laplace transform. For example the transfer function of a second order low pass passive RLC filter ...
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3answers
215 views

How can I model an optical filter using python?

Say I have an RGB LED which transmit intensity modulated signals, at one symbol transmission I want to send a symbol with all three chips.. Can I just model three bandpass optical filters like RF ...
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1answer
67 views

How to flter 70kHz signal with noise

I am trying to filter a noisy 70kHz sinusoide that goes from -2V to +2V. A factor 2 amplification should work. Any suggestion on which circuit to use? I tried to use an active bandpass filter ...
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2answers
69 views

Output Voltage Ripple Considerations

I'm working on a full bridge dc-dc converter, following the instructions on power supply cookbook. It has a 350V output and 2kW total power, 30kHz switching frequency I choose inductor current ripple ...
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0answers
83 views

Inverter EMI filter design

I'm designing an inverter with a switching frequency range of 10-40kHz. The inverter will run off of a DC power supply at a relatively low voltage (30-80VDC) and low power (~100W) for motor control ...
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1answer
31 views

Why signal coming out of a Constant K filter takes 0.5ms to stabilize?

I made a simulation of an audio amplifier with an input signal of 200 microVolts. The question is why my filter does not deliver the desired output, which operates between 512 Hz and 2048 Hz. From ...
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1answer
23 views

How to choose input filter component value for power supply

I understand that normally we'll modify the input filter after some measurement to meet the emission standard, but does anyone know on how we can estimate the initial value of this filter components ...
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1answer
53 views

Choosing resistors in series to make standard values

I am working on designing a precision analog filter for a university electronics project. The resistance values I am using (to meet the filter specifications) are not E96 values, so I am combining ...
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1answer
71 views

Is this output normal for a capacitor filter?

I have a question regarding oscillator outputs and capacitor filters. I'm trying to build a voltage regulator. I've already calculated and tested the transformer and rectifier, and also the filter ...
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1answer
539 views

What is the advantage of RLC low pass filter over two RC conneced in series?

I guess two RC in series should be a second order low pass filter. Because the transfer function will have s^2. And an RLC low pass filter is a second order filter for sure. So what is the ...
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3answers
292 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 ...

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