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Questions tagged [filter]

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

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33 views

What happens if we give two tones to an ADC? [sigma delta]

I have been working with Sigma delta ADC, where I generally use a single tone input and then check its spectrum at the output for the SNR, which is similar to as shown below: (just an example) I am ...
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22 views

Bandstop FIR Filter in Matlab

I have a problem here and I'd like some opinions. So, I need to design a Bandstop FIR filter and find its impulse response & frequency response in Matlab. I was thinking that, for the impulse ...
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2answers
43 views

Sallen-Key - how opamp input bias current changes cutoff frequency?

As in the title: what exactly is the impact of input bias current in Sallen-Key topology, for example the one below: I read that it can matter significantly, however I did not find anything more on ...
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1answer
45 views

How to find the transfer function of this first order active filter?

Going through Design with Operational Amplifiers and Analog Integrated Cricuits, in Chapter 3, problem 3.4 I am asked: The circuit of Fig. P3.4 is a noninverting differentiator. (a) Derive ...
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1answer
32 views

Detection of Acoustic signals

There is a scenario: There is a certain box which emits acoustic signals at 30kHz and you are trying to detect these signals using some sort of detector. I was wondering, would it be more efficient ...
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3answers
1k views

Why would you need an op amp for reference voltage when the voltage divider does the trick?

Is there a reason this schematic uses an op amp (AD8031) for the reference voltage of the op amp (AD8544) filter when the voltage divider already brings down the voltage anyways? Can the AD8031 op amp ...
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1answer
65 views

What would be the consequence of the inductor saturating?

The following is a section from a book where it is talking about decoupling by LRC at supply terminals. I highlighted the sentence where I didnt understand: I read that if an inductor has an iron ...
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1answer
28 views

filter composed of identical sections

I am trying to follow filter design scheme proposed here. The paper draws an analogy between electrical and mechanical filters. I think understanding this paper boils down to understanding equation ...
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1answer
56 views

Would an 8 order analog filter be enough for creating a bandpass filter of 8-40 hz?

I am creating a project in which I need to an analog active bandpass filter. The opamps used in the active filters do need any feedback hence are more like comparators. There is a power line noise of ...
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2answers
74 views

Feasibility of custom parabolic mic (amplified, bandpass filtered) for use with mobile phone app [closed]

I am not an electrical engineer, but I am up for a challenge and this is my first venture into electrical engineering. However I am beginning to think this may be a step to far! As a hobby I survey ...
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0answers
21 views

Input and Output Impedance of a SAW Filter

I am reading the datasheet of a SAW Filter B39162B4348P810. The datasheet doesn't say much about impedance of Input and Output ...
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2answers
52 views

Bipolar class-AB amplifier analysis questions

I am analyzing the following amplifier schematic Bipolar amplifier I'm wondering if their are any transistors that need to be cooled apart from the 4281A and 4302A output stage transistors? What is ...
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1answer
50 views

GPIO input state with undefined voltage

I am using PIC32MX350 series controller, on one GPIO , that is defined as input , and input that pin goes form one SMPS (PN : - PSC35 , IO Name :- AC out). Since SMPS IO is open drain we add a pull up ...
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1answer
84 views

Amplifying heavily filtered attenuated stopband signal

The picture is of a noise analysis, but a signal that may be present in V1 would be filtered in the same way as the noise. At 100 KHz, the noise is attenuated by about 42 dB, from 568 uV to 4.7 uV. ...
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1answer
48 views

Trouble with instrumentation and simulation of the common-mode response of a filter

I have been struggling to obtain the Bode plot of common-mode response of a filter. I first simulated it using LTspice, then I used a USB network analyzer. Both do not match each other and to the ...
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2answers
821 views

Cathode to cathode diodes in schematics

I'm trying to understand the following circuits for an MPPT, and I do have some questions: Why there is a capacitor C6 in parallel with R2 for the voltage divider for analog reading, and how was the ...
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1answer
46 views

Solving a circuit with a resistor in series with an LC circuit

I want to analyse a circuit that I've drawn above. It is a series connection of a resistor and an LC circuit (parallel type) driven by a sine wave of variable frequency. No assumptions can be made ...
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0answers
42 views

Calculating Required Bulk Capacitance

All, Lately I've been thinking more about bulk capacitance in my designs. Previously, I've been careful about part selection and placement for decoupling and filter capacitors during design. Once a ...
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1answer
69 views

How can I lower the Q factor for this filter?

I'm trying to make a 1MegHz CM filter using a common mode choke and some capacitors but I have a very high gain at lower frequencies instead of attenuation i.e high Q factor. A simulation shows the ...
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1answer
50 views

What are the series inductors used for in this filter?

Regarding the below filter, are the series toroid inductors at the very right end of the filter used for CM or differential mode filtering?: I think R and Cx are for differential filtering. And the ...
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1answer
40 views

Ultrasonic transducer actual bandwidth for filtering

I have a pair of ultrasonic transducers with a "Thick Resonant frequency" of 975 kHz ±30kHz according to the data sheet. I did a frequency sweep test where I could see that they performed best at a ...
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1answer
55 views

Smoothing cap vs filter for full wave bridge rectifier circuit

I am designing a circuit which requires high-voltage DC. My plan is to step-up my mains (120VAC) with a transformer and then pass that through a FWB. After the FWB, I want to smooth the signal into a ...
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1answer
39 views

Unexpected output for a passive filter circuit with low ohm resistor

With a simple filter circuit (either high pass or low pass), I'm seeing unexpected behavior in the o-scope output when I use a resistor with a low ohm value (e.g., 10 Ohms). Since a picture is worth ...
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1answer
29 views

Interpreting scattering parameters on a Smith chart.

I'm trying to become reacquainted with microwave circuits and how to analyze them, especially with a VNA. Just to get some practice I'm using Keysite ADS simulator. To get the feel of it I used the ...
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1answer
67 views

Easiest way to find transfer function of a lossless ladder filter after we finish design?

I have completed my Lossless Ladder BPF design, but I don't know how to find the transfer function of the resulting circuit without going through the slow and rigorous process of getting resistances ...
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0answers
26 views

Power Supply Transient Filtering

I'm implementing a Bluetooth module in my design and the modules datasheet calls for a filtering circuit on the 3.3V rail to get rid of transients when the LDO powers up (using a Torex XC6210 LDO). ...
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2answers
72 views

Analysing circuit for digital filter design

I have a hard time understanding how one would come up with \$H(j\omega )\$ given a circuit for an unknown filter. The circuit looks like this: I know that: \$H(j\omega ) = \frac{Y(j\omega )}{X(j\...
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0answers
24 views

Noise on Input Buttons for H-Bridge

I'm constructing an H-Bridge to control a linear actuator. I've done so by using a 2-channel relay module, some buttons, and a ESP32. I do not believe this is an issue of debouncing as I account for ...
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1answer
60 views

How to find the transfer function F(w) for this circuit? [duplicate]

Hi, My book on analogue circuits has this question and I have been stuck at it for the past three days or so. I am supposed to figure out the transfer function for the network as well as the cutoff ...
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3answers
110 views

How to calculate the transfer function?

I have The following circuit network (link to multisim) and i am asked to find the transfer function, the max and min value, the cutoff frequency, angle and the type of the filter. [the actual ...
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2answers
87 views

Does this look like a correct Bandpass filter?

A project task assigned me to make a simple series RLC bandpass filter with values B = 73kHz & freq center = 4.8MHz known. I use equations B=R/L and fc=1/(2pisqrt(LC)) to get the RLC values. ...
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0answers
57 views

Designing Bandpass filter with bandwidth and center frequency given?

I'm having trouble determining RLC values for a bandpass filter with these given values: Bandwidth: 73 kHz Center freq: 4.8 MHz I use equations \$B = \frac{R}{L}\$ & \$f_{center} = \frac{1}{\...
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1answer
45 views

Whats the difference between bode plot linear and cartesian?

As in title, Whats the difference between bode plot linear and cartesian in LTspice? In both cases i get V(f) but the values differ. Which plot will give me values of voltage at given frequency that ...
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1answer
90 views

What is the function of this circuit? (Included an op-amp, capacitors and resistors)

What is the function of this circuit? What is the role of the C2 in Op-amp's input? This is probably a filter circuit but I am not sure.
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1answer
59 views

Q: Need help designing Pre-Amplifier

I am trying to design a pre-amplifier before going into a power amplifier. I essentially just want to signal condition a little more before the power amplifier. Whats really confusing me is the input/...
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0answers
22 views

VCSEL temperature control with TEC: ADC average vs moving average filter

I have to control the temperature of a VCSEL with an on-DIE TEC and a PID-controller inside a FPGA. The ADC used to sample the voltage across a on-DIE NTC offers a samplerate of 1MSPS and the signal ...
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1answer
29 views

Determine the impulse response of the following discrete system

I'm not sure how they got the answer (provided below) for the following discrete system y[n] = x[n]- 2x[n-2]+ x[n-3]- 3x[n-4] the answer is given as .... h[n] = [1 0 -2 1 -3] why is this? any help ...
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1answer
78 views

Speaker crossover wiring

Came across some old Arcam speakers (cut open) and using the parts to build a bluetooth speaker box. Only problem is I can't figure out the wiring on the crossover/filter. The original speakers are ...
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0answers
34 views

Second order stable filter for RLC circuit

I have the above circuit which is described by the following differential equation: \${d^2y / dt^2+1/RC*dy/dt = 1/RC*du_1/dt + 1/RC*du_2/dt + 1/LC*u_2} \$ where \$y=V_c\$. What I want to is to ...
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0answers
16 views

Created this Filter Amplifier Circuit; How do I connect this load while maximizing gain?

*Filter Circuit on Left, Load on Right. To give some background, that load is supposed to replicate a long 12V power line (with other stuff on it) on which we will be sending AC signals on. The gain ...
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1answer
51 views

RLC bandpass filter

I am working on a circuit: simulate this circuit – Schematic created using CircuitLab My goal is to find \$ \omega_0, \beta, \$ and \$\varrho \$ The way I approached this problem was to ...
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3answers
167 views

How is this a High Pass filter?

Might be a dumb question, but isn't this a Low Pass filter? If not can someone explain me how it is a High Pass filter? This is the link for the complete document: http://www.circuitbasics.com/design-...
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1answer
35 views

Q: Amplifier's Output filter not having the Correct Cut off frequency

I am trying to design a output filter, a simply one (First order) just to play around with and for some reason when I run the simulation of it its not the correct Cut off frequency which it was ...
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1answer
54 views

What are the practical problems for designing low freq. chokes or EMI filters

The power line filters like commercial RFI or EMI filters usually composed of R L and C passive components and they don't usually work below under kHz frequencies. What makes it difficult or a ...
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1answer
106 views

How to get 50 Hz sine wave from inverter bridge driving PWM pins of MCU

I am using this circuit to see the sine wave coming from a DsPIC Pins to check the shape of sine wave created from my sine table. PWM frequency is 18 kHz But the sine wave does not seem to be ...
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4answers
4k views

Why are there so many vias on this board?

I was looking at the MMZ09312BT1 development board layout, and I was curious about all the holes they have on the board. Are these vias? What is their purpose (I heard somewhere that they are meant as ...
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1answer
56 views

How to bias(voltage offset) unity gain buffer

First post so sorry for any bad formatting. I'm trying to figure out how to bias my signal going through a non-inverting op amp with a gain of 1. Because I want a gain one just 1, it would just be a ...
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2answers
79 views

Bode Phase Plot of RC High-Pass Filter

I have been trying to understand Bode Phase Plot of RC High pass filter. I know that from my engineering that voltage lags behind the current passing through the ...
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0answers
36 views

Relay Contact noise Filtering

I am trying to filter relay contact noise when the relay contact goes from normally open to closed. The relay part# 833H-1C-C-12VDC.The relay contacts are made out of Silver Tin Oxide AgSnO2 I am ...
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1answer
57 views

VHDL unranged integer input ports bad practice?

I'm designing a customizeable interpolation filter and I'm looking for the best way to pass the coefficients (rather supporting points) to the filter. Below you see the current implementation. ...