Skip to main content

Questions tagged [active-filter]

An active filter is a type of analog electronic filter that uses active components such as an amplifier.

Filter by
Sorted by
Tagged with
0 votes
2 answers
56 views

Active Bandpass with "Tunable" F Using Potentiometer

I'm trying to construct a simple bandpass filter circuit using the multiple feedback topology with one op-amp (I'd like to leave out a dual-opamp approach for now). I'd like the center frequency to be ...
Nils L's user avatar
  • 103
0 votes
1 answer
48 views

Second order low pass filter cut off frequency calculation

I found this circuit which filters an incoming pwm pulse train from a Delta-Sigma ADC to an analog value. The PWM pulse has an amplitude from 0 to 5 V and duty cycle varies from 10% to 88%. And the ...
AK47's user avatar
  • 101
0 votes
1 answer
62 views

Are these filters suitable for this application?

I want to use the ADF4350 as a local oscillator and I want it to sweep as fast as possible from a start frequency A to the end frequency B the issue is the span is large and for that i have to use a ...
Tintin's user avatar
  • 75
1 vote
2 answers
66 views

LDO vs voltage reference when input signal is noisy

I am designing an active EMI-filter (AEF) with an op amp (LTC6227). The AEF suppresses noise from a DC/DC converter. Ther op amp requires a supply voltage of 9V and a reference voltage of 4.5V at the ...
Schafa's user avatar
  • 11
-1 votes
1 answer
80 views

Butterworth Filter for SMPS

If the performance of a Butterworth filter is dependent on the load impedance how do high voltage high power 1kW+ SMPSs manage to achieve smooth output ~100mV peak to peak across wide ranges of load ...
beardeadclown's user avatar
0 votes
0 answers
43 views

How to bias an input AC signal for active high-pass filter?

I have been trying to design a 2-way active crossover, with low-pass and high-pass channels. So far I got the desired frequency response but the transient response is not up to mark. Here is the ...
Sajil's user avatar
  • 13
0 votes
0 answers
47 views

Designing a D-FF in Virtuoso to create 90 degrees phase shift

I am currently trying to design a digital circuit in Cadence to produce a 90 degrees phase shift to a CLK signal within my current circuit. Below is an image of a D-FF setup as well as the output ...
soccernismo's user avatar
1 vote
0 answers
52 views

EKG active filter designs with single power supply

This is my beginners attempt at designing a EKG. I have printed out the PCB and attached all components to it to test it out. What I have observed are the following: 1. The outputs Vout1 as well as ...
Evank800's user avatar
3 votes
1 answer
268 views

Anti-aliasing filter for 3.3 V ADC at 1 MHz

I am designing an anti-aliasing LPF for a 16-channel ADC on a custom STM32F415-based board. This design will ultimately be put on a car and used as a DAQ. I am planning on running the ADC with a 30 ...
ABashara's user avatar
1 vote
2 answers
279 views

Band pass filter zero crossing distortion

Second stage output Drawing I built the above bandpass filter using lag lead combination for filtering +/-2.5 Vp-p square wave @ 125 kHz, but the extracted sine wave have zero crossing distortion,...
dhuwarkesh's user avatar
3 votes
2 answers
277 views

Open loop gain of Op Amp 20 dB lower

I need some clarification regarding the open loop gain of Op Amp. I tried simulating this active BPF on LTspice. The Avol of the Op Amp U6 (UniversalOpamp) is 1meg and its GBW is 10meg. My ...
Res999's user avatar
  • 31
2 votes
3 answers
66 views

Twin-T Notch has output with no input

For Context: I am trying to implement a hardware Twin-T Notch Filter to attenuate 50Hz PLI in a sEMG circuit. I've used the circuit proposed by Analog Devices on page 17 of the AD8244 datasheet, but ...
Luke Dettorre's user avatar
0 votes
1 answer
41 views

Frequency Companding

I have a theory question. I want to know if compressing and expanding audio frequencies is possible or perhaps already accomplished. As a point of reference, audio companding is a signal processing ...
Dereck's user avatar
  • 652
1 vote
3 answers
104 views

Why is my band-pass filter self-oscillating?

I built a bi-quad filter based on the AD8054 (consist of four AD8051 op amps) following exactly the AD8051/8054 datasheet. After I power up my op-amp, the filter entered a steady self-oscillating even ...
BenjaminZ's user avatar
3 votes
1 answer
127 views

Is it possible to achieve a square root analog filter?

I am attempting to create a (3/2)th-order active low-pass filter circuit, with a zero[es] at ω=10000 and pole[s] at ω=100. The only way I can think to do this is to simply cascade three simple first-...
Jonas Fletcher's user avatar
0 votes
1 answer
27 views

Feasibility of Using a VBT as an Analog Radio Source or Audio Equalizer

Can anyone with more experience give me some insights on the feasibility of using a Variable Bandpass Tuner as an Analog Radio source? Here is my VBT Design based off a state variable filter: Its ...
Nicholas Pacheck's user avatar
0 votes
0 answers
78 views

How can I create phase shift (in degress) of analog filters in Pspice?

How can I create phase shift of filters in Pspice? (like red curve) also measure the delay at the output for a band pass filter created cascaded amplifiers.
Electronx's user avatar
  • 756
0 votes
1 answer
73 views

Active crossover filter for AB AMP

I want to use a STA540 amplifier IC in Stereo plus bridge configuration (page 11, figure 6). The idea is to have the chip drive two 4 Ohm tweeters and one 8 ohm Mid/Woofer. Since passive crossover are ...
Status Re's user avatar
  • 225
1 vote
2 answers
87 views

Active passband filter with higher gain than open loop

I'm desgining an active band pass filter using a LM324 op amp. The signal I need to amplify is centered on 20kHz and has a width of around 1kHz. Looking at the open loop gain of the LM324 I see that ...
Michael Vaispaper's user avatar
0 votes
2 answers
209 views

Active low-pass filter design

I have read TI's application note Active Low-Pass Filter Design a couple of times, particularly page 19. Section A.1.1 shows some simplified steps for designing a filter by choosing m and n as a ...
KaleM's user avatar
  • 473
1 vote
1 answer
135 views

Loss of 2nd order behavior on 2nd order low-pass filter

I have a 2nd order Sallen-Key Low-pass filter, cut-off frequency of 170Hz. When attached to a perfect source, this is the bode plot. As expected, 40dB/decade response. The low-pass filter is used as ...
HFOrangefish's user avatar
0 votes
1 answer
70 views

Simulating a 2nd order filter provides a 1st order response

I'm trying to design a filter with a bandwidth of 150Hz, center frequency of approx. 60Hz, with a roll-off of 40dB/decade. I am following the design of a 2nd order Multiple Feedback Band-Pass filter ...
HFOrangefish's user avatar
0 votes
1 answer
120 views

Multiple Feedback Band-pass behavior at low (<1) quality factor

I'm trying to design a filter with a bandwidth of 150Hz, center frequency of approx. 60Hz, with a roll-off of 40dB/decade. I am following the design of a 2nd order Multiple Feedback Band-Pass filter ...
HFOrangefish's user avatar
1 vote
3 answers
388 views

Analyzing an LM358 module circuit

I'm beginner in amplifiers and fiter circuits. I am working on a project that uses an LM358 module. Here is the schematic: I have several questions Is the schematic a two stage amplifier with first ...
Gusti Made Arya Wijaya's user avatar
1 vote
3 answers
157 views

Reason to increase output impedance in a non-inverting op-amp

In the schematic above a non-inverting op-amp filter is shown. Why is R2 added within the feedback loop? Does it serve any purpose? Outside the feedback path (right before C2) it could serve as a ...
Asd2gogo's user avatar
0 votes
0 answers
60 views

Fg limit frequency calculation. Active band-pass filter

I need help with calculating the cutoff frequency Fg. There are several formulas, but I don't know which one to use because every time I get out a different value in (Hz). Below is the schematic of ...
OseRu's user avatar
  • 1
2 votes
2 answers
226 views

Find resistors for an inverting op amp band pass filter

I'm trying to save a problem that shows the following band pass filter: Note: the op amp doesn't need to be a TL081, it's an abstract, ideal op amp. I need to find resistors \$R1\$ and \$R2\$ so that ...
Dan's user avatar
  • 145
0 votes
1 answer
58 views

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 ...
Electronx's user avatar
  • 756
0 votes
0 answers
52 views

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? ...
Electronx's user avatar
  • 756
0 votes
1 answer
131 views

How can I calculate the parameters of an inverse Chebyshev active filter?

I'm currently designing an inverse Chebyshev 7th order low-pass filter with three 2nd-order low-pass notches and an RC low-pass filter. I've already used Simulink to obtain the s-domain transfer ...
PAT's user avatar
  • 3
1 vote
0 answers
113 views

Bandpass Amplifier

This is my frequency response , the point is if i change the capacitor values C1 and C4 my signal distorts on the second lobe in time domain and gain curve is not flat in the range. MY bandwidth is in ...
Electronics4learning's user avatar
0 votes
2 answers
141 views

Frequency detector/comparator problem

I have recently learned about schmitt and comparator op amps, and I came up with an idea to build a "frequency comparator" (if it is called like this). The function of this circuit is to ...
David Ab's user avatar
  • 129
0 votes
1 answer
237 views

How can I calculate the gain of this high pass active filter?

This is the circuit I'm trying to make: This is the circuit I made for simulation in Proteus: These are my measured values as a result of Proteus simulation. This circuit is used to measure the ...
bevren15's user avatar
4 votes
1 answer
166 views

6th-order filter simulation

I've designed a 6th-order filter using Analog Devices' online filter wizard. The filter has a cutoff frequency of 2MHz, and I'm aiming for 50dB attenuation at 5MHz, with a continued roll-off beyond ...
H Ket's user avatar
  • 51
-1 votes
3 answers
140 views

Active low pass filter is there any virtual ground point? If yes how can I derive?

I'm learning this MFB active LPF. My questions regarding this as follows: How to derive transfer function for this configuration? Is there concept of virtual ground exist? If yes can you explain ...
Bhushan Waghe's user avatar
2 votes
2 answers
197 views

2nd Order Butterworth filter design. How to find "m" and "n" values

I was reading this article Active-Low Passfilter design from Texas Instruments, and I've been racking my brain all day trying to find how they determine the values for "m" and "n" ...
belmont Dubois's user avatar
0 votes
0 answers
73 views

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 ...
atıf koçak's user avatar
2 votes
1 answer
121 views

unfamiliar notch filter configuration [duplicate]

This is a configuration of the notch filter that I saw in some design. It is very different from the Active Twin-T notch filter configs that show up on a quick google search. Any idea what is going on ...
roaibrain's user avatar
  • 407
0 votes
4 answers
154 views

Analysis of an RCL Filter Utilizing a Potentiometer as R

I am trying to calculate the parameters ζ, Q, Fo, Gain (dB), and BW of this circuit. I am confident in the following equations: Fo = 1 / (2 * π * √(L2 * C1)) ; Q = 1 / (2 * ζ) ; BW = Fo / Q R2 = R5; ...
flower.fish's user avatar
1 vote
1 answer
235 views

How can I determine if a Sallen-Key filter will be stable using LTSPICE and analytical expressions?

I am trying to determine if a Sallen-Key filter that I designed will be stable. In order to do this, I am trying to simulate the filter in LTSpice and measure its open-loop phase margin. The filter is ...
Riccardo Fagiolo's user avatar
1 vote
1 answer
69 views

Butterworth filter not getting as much gain as expected

Using the Analog Devices Filter Design Tool, I have created a band pass filter for a 1MHz input with 20dB of gain. I have implemented the circuit in LTSpice with the expected behaviour, however when I ...
LK26's user avatar
  • 31
0 votes
1 answer
83 views

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 ...
Zhi's user avatar
  • 41
1 vote
0 answers
64 views

What op-amp can I use in this output filter recommended design?

I'm working with the Cirrus Logic CS42448 codec and would like to implement an active filter output to differential audio signals. The output should be line level to be connected directly to external ...
Emerson's user avatar
  • 423
1 vote
2 answers
87 views

High pass filter doesn't get back original signal?

If you simulate this (from https://www.circuitlab.com/editor/#?id=3p73kzybb5r8): simulate this circuit – Schematic created using CircuitLab You see this: The input is a combination of the ...
roaibrain's user avatar
  • 407
0 votes
1 answer
69 views

I want to implement a 2-active crossover circuit with LM833 and amplify it using LM386 and now the problem is I couldn't understand the circuit [closed]

I can understand up to certain level that we used a buffer, low pass filter but I can not connect with circuit and coming to components we used 120 Ω, 6.8 nF for active crossover with power supply + ...
Yuva Praneeth Reddy's user avatar
0 votes
0 answers
51 views

HP filter for MHz pulses

I need a high pass filter for my measuring setup and I'am a total newbie to analog filters. I have weak hf pulses (0.5-1.2 MHz, 10 mV) superimposed on lf sine wave (8-40 kHz, up to 5 V), I'm ...
Nikd0's user avatar
  • 9
1 vote
1 answer
130 views

Calculate parameters of active high pass and low pass filter given for EOG circuit

The circuit is from here. The opamps are : OPA2335 (dual channel because of horizontal and vertical electrodes.) I don't exactly understand how to calculate R and C values based on the 0.5 high pass ...
roaibrain's user avatar
  • 407
2 votes
3 answers
373 views

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?
kene02's user avatar
  • 538
-1 votes
2 answers
1k views

Why are active filters preferred over passive filters?

This question was asked to me in an interview. I replied that passive and active filters both have their merits and demerits : Unlike passive, active filters provide mechanism for gain adjustment ...
MAJID AHMAD's user avatar
1 vote
1 answer
42 views

How to compare these parameters through a cost function?

I am comparing three filter designs based on different criteria. Basically my question is about what is like the best way to compute like a number, or figure of merit to evaluate this criteria. ...
Granger Obliviate's user avatar

1
2 3 4 5
10