A filter modifies signals based on their frequency.

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53 views

Trying to determine the output of a RC-filter with load

I have a low pass filter like this: simulate this circuit – Schematic created using CircuitLab \$V_{out}\$ is measured right after \$R_1\$, which I suppose means that it is measured over ...
2
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1answer
123 views

What is the need for the extra resistors in this equalizer circuit?

I am working on a final project for my circuits class to design an audio amplifier. We are creating an equalizer circuit that has passive high pass, low pass, and band pass filters. Every where I ...
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2answers
41 views

8th order butterworth frequency response

Ok I'm sure people are getting tired of seeing my filter questions but here's another one. With my new understanding of 2nd order Butterworth filter design I set out to try to design an 8th order. ...
2
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1answer
57 views

Basic Filter Design

Need help with basic filter design. Firstly there is a low-pass filter(pictured below). I am supposed to derive an expression for the amplitude of the output voltage as a function of \$R_1\$, ...
2
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1answer
52 views

Op-Amp difference amplifier low-pass filter

I have the following (summing, single supply) difference amplifier circuit: How can I extend this circuit to a 1st or 2nd order low pass filter, with a corner frequency at about 20kHz.
2
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3answers
220 views

Why do we need bulky filters at the input stage of SMPS designs?

I usually see costly and large filters at the input stage of switch mode power supplies. Isn't the AC signal already filtered by the large capacitor (the 100\$\mu\$F one in this example) after the ...
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0answers
40 views

Opamp filter cutoff frequency not as expected at higher frequencies

I'm still working on learning Butterworth filters. So far this weekend I went back to school, read about Lapace transforms, poles and zeros, Saleen key design, and finally back to Butterworth filters ...
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1answer
50 views

filter whose gain increases from minimum to maximum for frequency 400Hz to 1kHz

I want to design high pass filter whose gain should increase from minimum to maximum ( minimum upto 400 Hz maximum for 1 kHz) linearly or exponentially. It must be an active filter and my input signal ...
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2answers
47 views

Is the cut-off frequency for each high order butterworth filter the same or different?

From reading I see that I can calculate my cut-off frequency for a given Butterworth filter using the equations below. Let's say then that I have a 8th order filter, and I'm going to make it out of ...
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2answers
68 views

High Order Butterworth Filter Math

I'm trying to learn more about high order filter design, with my goal being to design an 8th order Butterworth lowpass filter in spice, then in the real world. I've been reading a filter book I have ...
0
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2answers
54 views

How to eliminate 50 Hz noise from amplifier's output

My goal is to amplify signals with a frequency from 100Hz above. My circuit is looking as the picture below. With an oscilloscope, I am trying to measure the output of the amplifier. If the input of ...
2
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2answers
64 views

Pass DC through (passive) highpass filter?

Background: I'm a student, working on my final year project. I am designing a front end for a software defined radio. We have an IF frequency at 36Mz (and a BW ~8MHz). We are bandpass sampling this ...
3
votes
2answers
59 views

Relationship between order of filter and impulse response?

I see that the slope of the frequency response of a filter (such as the Elliptic, Butterworth...) becomes steeper as its order increases; for instance, a low pass Elliptic filter with an order of N=3 ...
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4answers
420 views

Purpose of 2 resistors in high pass filter?

In the picture below, what is the purpose of R1? Compared to a high pass filter with 1 resistor, how does this affect Fc? Thank you.
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0answers
31 views

passive filters in power quality

In power systems,how does cost of passive harmonic filters change with their rating and tuned frequency.This question is for a medium voltage distribution system.
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1answer
41 views

Sanity check: Input and output filter for a stacked pair of DC/DC converters

In my current project, I need voltages of +/- 30V and +/- 15V for analog control purposes. The current on the 30V rails is fairly limited, ca. 70mA max on one rail and <10mA on the other. The 15V ...
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0answers
20 views

Trouble in proteus isis

I need to design a few components in Proteus. Due to complexity of the design ( and size of circuit), I decided to use the sub circuit feature. I made a block diagram of my design and edited its ...
1
vote
1answer
63 views

what's the difference between these two low pass filter types

Is there any difference between these two types of lowpass filters? I see the equation is the same, I assume they're both first order then. Just curious if there's any practical difference. Maybe ...
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0answers
49 views

LC Low pass filter with high cutoff frequency

I want to design an LC Low pass filter with cutoff frequency of 1000 MHz. the problem is that I want to avoid using low capacitor values, i.e: 3 or 4 pF. My Zo is 100 ohm Any design suggestions ?
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0answers
42 views

In the under-damped RLC Circuit, one constant is imaginary, but there can't be imaginary current

I'm just learning about RLC circuits and all the math makes sense, but one thing has been bothering me. In the derivation of the equation for a underdamped, series RLC, the roots to the ...
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2answers
42 views

Linear Phase Response

In many cases it is demanded that the filter has a linear phase response. (like in case of FIR ). Why linear is so important? Why not constant or anything else(any other shape)?
1
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1answer
76 views

Finiding composition of circuit from frequency response and bode plot

I have the following bode plot and nyquist plot result of an unknown DUT (it is a filter I asume!). I wonder what kind of arrangement it has in terms of being a series or parallel RC or RLC ...
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1answer
58 views

Guitar Pre-Amp stage/filtering and STM32F4

I am currently involved in an academic project which the topic is to design a Digital Tuner for Electric Guitars. My knowledge of electronic is very basic, so here I am. I need to pre-process the ...
0
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3answers
77 views

RC filter transfer function and gain

For a standard basic RC Filter, the transfer function is as follows: $$ { V_{out} \over V_{in} } = H(j\omega) = { 1 \over 1 + j\omega RC } $$ However, when simulating the circuit, I find the output ...
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3answers
65 views

How can I achieve symmetrical analogue low-pass filtering?

I am experimenting with VCFs for an analogue music synthesiser. Initially I tried a 3-stage low-pass filter based on the sinewave-generator circuit in the LM13700 datasheet but having removed the ...
0
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1answer
129 views

Comparison of Series and Parallel LC Filters for Noise Reduction

Since there are two basic types of LC circuits that can be used for passing/blocking signals, I'd like to know the differences when using series or parallel LC circuits for noise at a known frequency. ...
0
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1answer
46 views

Transfer function and its magnitude

Can anyone make the transfer function and magnitude of the transfer function more intuitive for me? I understand using them but I feel like there is still a gap in my understanding. I would like to ...
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1answer
49 views

Implementing High Pass Filter in Simulink

I am trying to implement the following block diagram using Simulink in Matlab. I am having trouble getting the high pass filters to work properly. To do the filtering, I am using the First and ...
0
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1answer
37 views

Is it possible to design cascaded LC filters with inductors sharing the same core?

I want to design an higher order LC filter for filtering out a power signal. In the theoretical design, the inductors are supposed to be on separate cores. But in practice, it will be very costly and ...
0
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1answer
66 views

Lowpass filter design with transimpedance and difference amplifiers

I have a DDS chip with complementary current outputs that I need to filter. I'm using a design like this: I need a different cutoff frequency, however - 2MHz instead of 50KHz. Note that I'm not ...
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3answers
56 views

Physical significance of group delay

What is the physical significance of the group delay of a system/filter?. Why is the slope of the phase response critical in a communication system.
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2answers
72 views

Are those two filters equal?

Are those two filters equal to each other in their functionality? Of not, what is the difference between them mathematically speaking (zeros, poles, etc)? Also, what is the difference in their ...
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1answer
47 views

Band pass filter [duplicate]

What is this bandpass filter transfer function derivation? http://imageshack.com/a/img674/9016/mKXqCQ.jpg
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0answers
52 views

Noise on audio circuit when powered by USB

I built a simple microphone boost circuit which works well with a 3V coin cell however when I switch to USB to power it (battery removed, of course), there's a bit of noise in the 200Hz to 10KHz ...
0
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1answer
31 views

Size of passives for active filter

I am working with the CS42436 codec, and in their datasheet, they have recommended values for components to be used in an active filter that takes the differential outputs from the DACs and converts ...
2
votes
1answer
71 views

Can I replace capacitor with multiple lower value capacitors in filter?

Can I replace higher capacitance value MLC capacitor in Sallen-Key topology filter with 2-3 lower value capacitors in parallel (with total capacitance equal to replaced cap)? I tried it in TINA-TI and ...
2
votes
1answer
71 views

A-D conversion: effect of adding more bits

Say you have a digitizer that's converting an analog signal and feeding it to a microprocessor for whatever you'd like to do to it. How would increasing the number of bits of the digitizer affect the ...
2
votes
2answers
100 views

A simple RL circuit, getting transfer function, matching with results

I'm doing little lab exercise with an RL circuit. I need to check if I did this analysis right, because the numbers I got and the numbers that should theoretically be there are so far off, I figured ...
7
votes
1answer
169 views

Is it possible to create an IIR filter in an FPGA that's clocked at the sample frequency?

This question is about implementing a IIR filter in a FPGA with DSP slices, with very specific criteria. Lets say you're making a filter with no forward taps and only 1 reverse tap, with this ...
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2answers
111 views

Why does my bandpass filter act as highpass?

I have designed a bandpass filter. Here is the circuit and spectral characteristic: As you can see from the response curve, it has cutoff with the peak ranging from 260 kHz to 290 kHz. Here is ...
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0answers
110 views

A band pass filter simulation in PSpice

I designed a Constant K (I don't remember the constant K) LC band Pass filter with lower cut off frequency 1 KHz and upper 5 KHz. Using the value of K, I deduced the values of L and C and made the ...
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2answers
254 views

Understanding cause of arcing in AC filter circuit

I have an induction hot-plate that one day blew a fuse in my distribution panel when plugging it in. (With the obligatory smoke from the device of course) On visual inspection, only the AC filter ...
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2answers
45 views

Passive Filter Negative Insertion Loss

Can someone please explain to me how a passive filter could possibly have a negative insertion loss? In the attached picture, this can be seen in the C or D curves where the insertion loss dips below ...
1
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1answer
58 views

Is it possible to calculate the load resistance in a full bridge rectifier when given only power, inductance, and input voltage?

I'm given a full bridge rectifier circuit with values for power, industance, and RMS input voltage: [P = 380 W, L = 85 uH, Vs = 115 V]. The question states to 'select' output resistance for a ...
1
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3answers
127 views

RC bandpass filter, what's first: low-pass filter or high-pass filter?

I want to do a RC bandpass filter can I use low-pass or high-pass at the beginning or does it have a specific sequence? First low-pass then high-pass, or first high-pass then low-pass?
1
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3answers
151 views

Sin signal from PWM

I wrote a program in order to use Pulse Width Modulation to simulate a sinusoidal signal. Added a low pass filter to get rid of the noise and the traces of it being a discrete signal. Added a half ...
3
votes
2answers
201 views

What do ripples in frequency response curve of filters depict?

I am trying to understand the frequency response curve of various types of filters (Butterworth, Chebyshev etc). The curves are shown here for reference : One thing I do not understand is what do ...
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votes
1answer
66 views

Inductive filter vs capacitive filter: Which is better and gives less THD on the input side?

I have a generalised statement that total harmonic distortion (THD) on input side for input supply current is more for single phase diode rectifier with capacitive filter as compared to single phase ...
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2answers
73 views

Filter for radio receivers

I am in need of an intermediate frequency (IF filter) for somewhere around 200 Khz as intermediate frequency. However, I know just the bare minimum of filter design ( learnt all that a couple of days ...
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2answers
94 views

Order of resistor/capacitor in bandpass/highpass filter

Is there any particular reason to prefer one of these filter designs over the other? Theoretically, they are the same. Practically, does changing the order of the resistor and capacitor have any ...