Questions tagged [impedance]

Impedance defines the voltage/current characteristic of any dipole circuit.

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Zeroes of transfer function

In 'Franklin F kuo's book it is written that "The zeroes of transmission of the ladder occur at the poles of The series branch impendences or at the zeroes of shunt branch impendences" here ...
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RF Matching Problem

I am having some fundamental issues trying to create an impedance matching network for an 868MHz antenna, I have a PI network between the antenna's connector and the antenna feed point I have measured ...
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59 views

Arduino analog input value oscillating, why does the DMM work and arduino not so much

I am measuring voltage output from a device with 10 kohm output impedance with an arduino analog input pin. I see what I would expect with a multimeter, but with the arduino I get either garbage, or ...
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1answer
47 views

Controlled impedance traces necessary between line driver and series termination resistor?

I'm designing a line driver circuit with the SN74BCT25244 chip. The chip has a rise time of ~10 ns into an open circuit based on my own scope testing, but we are only wanting to drive the signal at a ...
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29 views

CAN Bus Nominal Impedance

I understand the reason for choosing a termination resistor of 120 Ohms for the CAN bus to avoid reflections but why was the nominal impedance of the CAN bus cables required to be 120 Ohms by the ISO ...
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1answer
95 views

Make a Negated General Impedance Converter

A General Impedance Converter (GIC) looks like this: Source: http://www.ee.nmt.edu/~wedeward/EE212L/SP15/ImpedanceConverters.html Where $$Z_{tot} = \frac{Z_1*Z_3*Z_5}{Z_2*Z_4}$$ But I need a circuit ...
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LDOs in series and impedance

I am unable to understand one thing. I have a 2 LDOs in series , the first a regular LDO with a normal impedance and second is a shunt regulator with an ultra low impedance . What will my load see... ...
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55 views

Why does my BA speaker truncate the negative part of the waveform?

I'm developing a custom earphone and I'm having some issues with producing a clean sound from my balanced armature (BA) driver (Sonion 31D005/8). I've come up with a pretty standard circuit (see below)...
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82 views

How to find the impedance of this RLC circuit?

I'm trying to find the impedance of this RLC circuit (sorry for awkward notation of Q instead of I and P instead of V due to that this scheme comes from an analogy of electrical circuits with 0D ...
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2answers
74 views

I need to measure the impedance of the system, is it better to measure the resistance or capacitance?

The goal of this project is to measure Retinol levels in the blood. To do this I will be use two electrodes, one of which will be coated in nanowires. These nanowires will then have antibodies that ...
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1answer
51 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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82 views

Simple method to calculate output impedance of source follower

Output impedance of source follower without Rs would be 1/gm. However, if you add Rs the ...
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Impedance matching through via and signal trace of 2 layer board

Due to tight space constraints I need to pass my LTE signal (800-1800 MHz) through a via. The proximity between the antenna connector and the modem is very short (literally on the other side of the ...
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Why is impedance represented as a complex number rather than a vector?

I am trying to understand why impedance is not represented using vectors. I assume it is due to complex numbers having the property that $$j = \sqrt {-1}$$ but with my limited knowledge I can't see ...
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2answers
91 views

Impedance in sine DC

If we have a DC sine signal. Can we say that capacitors and inductors have impedance despite not being AC? If yes then what will the formula look like? And the opposite if we have an AC square signal ...
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48 views

Emulate impedance response using RLC components

I need to emulate measured impedance response of some blackbox using only RLC components. Measurements: ...
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2answers
68 views

How to choose speaker impedance for a VERY specific application?

Ok, so this may be a long post. I want to preface by saying I have very limited electrical engineering knowledge, so thank you in advance :-) I'm working on a medical device for a college project. ...
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Electrical circuits homework

I am pretty new to circuits analysis and I have the following problem as homework: ig2(t) = 4sin(ωt + π/4), e3(t) = 12sin(ωt + π/4), R1 = 10 Ω, ωL1 = 4 Ω, ωL3 = 3 Ω, 1/(ωC2) = 6 Ω I have to calculate ...
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75 Ohm Coaxial Cable Used On a 600 Ohm Output

I'm working on restoring an HP 211A square-wave generator and I'm looking to add a shielded cable to the 600 ohm output. I've got some spare 75 ohm RG59 cabling and I was wanting to know if using that ...
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1answer
50 views

Why is 370HR used for controlled impedance rather than FR4?

I tried to put together a quote for a 4-layer PCB with controlled impedance (Displayport, so 100ohm differential +/- 10%). I used the online quote tool on Advanced Circuits (4pcb.com). The quote ...
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1answer
33 views

Finding the total impedance and voltage across open terminals

The question that I'm trying to solve is the following: In the circuit shown below, what is the total impedance in ohms across the open terminals? What is \$v_{T}\$ if \$v_{L}\$ is 80 vrms? This is ...
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1answer
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Parallel trace signal integrity: Increasing width to match characteristic impedance vs increasing trace gap

Imagine you are routing a large number of single ended high speed traces through a long narrow gap on a PCB. Lets say these are ultra-high speed SD signals, so a 208MHz clock. The traces should be ...
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1answer
58 views

How to connect a low impedance RF amplifier to an antenna?

I'm trying to maximize power transfer from my amplifier to my custom antenna, but am unsure about how to properly impedance match the system. My amplifier has an output impedance of 4Ω, but is ...
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25 views

Realisation conditions for impedances

Given a frequency function, which conditions should it fulfill to be realisable and implemented as a one-port impedance? I know that for it to be realisable with passive RLC components, the frequency ...
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1answer
83 views

Help with output impedance of a circuit

We have to find the output impedance of the following circuit, where the output is the upper pin of R4. If I try to compute it with LTspice, I get about 55 Ohm, but whenever I try to work on it ...
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Measuring the impedance of dry EEG electrodes?

Does anyone have recommendations or good resources on measuring the impedance of active dry EEG electrodes? I'm working on a project to create my own electrodes, and I'm pretty new to the electronics ...
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Equivalent impedance seen at input terminals of inverter stage

I am using a three phase interleaved DC-DC boost converter which is followed by the three phase inverter. I need to model the impedance seen by the DC-DC converter when inverter load is connected to ...
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1answer
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Am I using the right resistors with these MOSFETs for an ESP8266 controlled LED strip?

this is my first question here. I hope I don't mess it up. I made a WiFi controlled LED strip about a year ago. The LED strip is one of the "dumb" (no individual pixel control) 12V ones and I used a ...
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What does a High Impedance input mean for an ADC

The ADC ADS131M08 list a feature: Can someone elaborate what this feature implies? Does this mean i can place a 300 Kohm resistor in series with the inputs? There is even a reference on page 88 with ...
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1answer
29 views

ST ST25R95 - NFC chip - Impedance of transmission lines

I will supply the chip with 3.3V, and the datasheet of ST25R95 IC shows it has a ZOUT of 27R at this condition. There is a circuit between NFC antenna/coil/inductor and the IC, the LC filter and ...
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108 views

Why adding capacitor to a 10x passive oscilloscope probe

I'm trying to understanding input impedance and its circuitry of a simple, passive oscilloscope 10x probe. From reading Input Impedance of an Oscilloscope and the video EEVblog #453 - Mysteries of x1 ...
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Piezoelectric Backscatter Communication

I am currently working on a project. We have a metal bar as test object and at each end we stuck a piezo disc. I am trying to use one piezo as a sender and the other as receiver or reflector. I tried ...
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1answer
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Formula derivation of Doherty power amplifier from circuit diagram

I'm having a hard time understanding how formulas are derived from the diagram of a simple Doherty power amplifier circuit, as pictured below. While I understand the concept behind load modulation ...
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1answer
35 views

Impedance Matching of an Antenna

I am reading about antenna design and have a few questions which I could not get clarified. I read about "Stubs". I got to know that Stubs are used for impedance matching of an Antenna either by ...
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Two port networks - Why are shared Z-parameters not negative?

In basic electronics we learned that to solve a circuit using mesh analysis, the shared impedances had to be negative. For example in the circuit bellow, the system of equations would be: $$\begin{...
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What is the best way to measure current and voltage through a diode

I am reading the book Learning the art of electronics and on a part about diodes, the author pointed out that in characterizing a diode(I, V relation ) there is an unavoidable error due to the ammeter ...
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relation between transmission line & circuit impedance

What is the relation between the impedance of lumped components and the characteristic impedance of transmission lines? I have noticed that in some cases transmission lines are loaded with lumped ...
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2answers
51 views

How does Impedance matching equation work out from original link?

From this link: L-Pad Impedance Matching Equation How do you get those two equations? They do not look like a voltage divider formula, do they? Questions repeated here: First answer from Adil ...
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1answer
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Should I cut away the ground pour above a diffpair on the first inner layer, which are Z-matched to the ground layer (L2)?

I'm routing diffpairs on the 1st inner layer of a 4-layer pcb which are Z-matched to the 2nd inner layer which is entirely a ground pour. The top layer has traces and routing AND also a ground pour ...
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1answer
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Is my thinking right for the simple harmonic circuit

If this is a simple harmonic circuit, then what is the \$X_C\$? I know harmonic circuit means that there is no value in the imaginary part of the impendence or admittance, that is, \$Z_{th}=R+0j\$ or ...
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Impedance and resonance frequency of a bias tee

I am a beginner trying to learn about combining impedances and solving for the resonance frequency. I am solving a circuit: simulate this circuit – Schematic created using CircuitLab and I ...
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2answers
76 views

Speaker impedance and voltage

There is a device which has output impedance 150ohms. If my headphone has either lower(30ohms) or higher (400ohms) impedance can I use it or sound will be too low/high and it will be unsable? Also, ...
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1answer
54 views

Deriving the Impedance equation of a RLC circuit (with 2 Inductor)

simulate this circuit – Schematic created using CircuitLab During this lockdown I had some time in hand and decided to learn more about impedance. So I gave myself a project, trying to create a ...
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Advice for 90 Ohm traces of a USB 2.0 HUB

I am designing a USB-hub that has many USB traces. I followed some guidelines online and read forums. Based on my understanding of a 4-layer stack-up, one of the best set-up I chose is 8 mil trace ...
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2answers
42 views

What is impeding current when voltage is stepped up in a transformer? [duplicate]

What is physically impeding electric current when a transformer steps up voltage? Is there some EM field along the conductor impeding electron movement? FYI, I'm not asking about losses or leakage. (...
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Cadence - input impedance

What is the best way to find the input impedance of an amplifier using cadence software? is it by using the smith chart or is there an easier way? do I have to add an additional components to the ...
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1answer
51 views

How to calculate the PI model equivalent transformer parameters

I have a power transformer with the transformer ratio 200kV/100kV, 100MVA rated power, and specified R = 0.001 p.u., X = 0.05 p.u. For a calculation I have to make, the literature I am using is ...
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48 views

Typical impedance values for a large 150 MVA power transformer

I am trying to calculate the impedance in ohms for a 220kV/110kV 150MVA transformer (European grid), but the values I am getting are not in range of values I usually see in online examples. X in p.u....
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Can you reduce audio noise by decreasing input impedance with a resistive load?

First asked this over at sound stackexchange but they pointed me over here as a better place for it. A general question but inspired by a specific example so framed as such. I have powered studio ...
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Simplifying expression for total impedance of an equivalent circuit in EIS

In electrochemical impedance spectroscopy applied to impedance response of an electrode, when charge transfer resistance \$R_{ct}\$ and Warburg impedance \$W\$ are in series in an equivalent circuit, ...

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