Questions tagged [impedance]

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

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Are T-parameters the same thing as ABCD parameters?

S-parameters can be converted to either T-parameters or ABCD-parameters, and both are considered a "transfer matrix". The conversion from S-parameters to T- or ABCD-parameters are defined ...
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Reduce Resistance and Heat Dissipation in a fuse

I have a 240VAC, 200A switch. It has very tight space requirements, and has to be sealed - so no external air flow. I need to minimize heat as much as possible. I have redesigned bus bars, spacing, ...
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Can admittance (Y) be used to calculate reactance when L and C values are calculated from the Y12 and Y11 parameters like normal as X=XL-XC?

My original question sought to understand the relationship between S-parameters and reactance. In the process of trying to figure that out, this second question arose. The actual question is at the ...
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Designing of a ribbon microphone (sort of) output transformer

I'm currently working on an experimental string musical instrument. It isn't my invention though. The source of inspiration called Dvina has an unusual pickup system. It senses the current induced in ...
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How are S-Parameters and Reactance related, can one be calculated from the other?

I know that, for example, \$X_L=2\pi f L\$ will calculate reactance of an ideal inductor, but can this be calculated for a real component model? Given the S-Parameter values at some frequency from an ...
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Is the resistive component of impedance the same as DC resistance for a given component?

If I calculate the impedance of a component in an AC circuit as Z=V/I, will the resistance component of that impedance, ZcosΦ, be the same as the resistance when that same component is in a DC circuit ...
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Method for building a test fixture for the 4294A impedance analyzer?

I have an Agilent 4294A, a 40Hz-110MHz impedance analyzer, but no test fixtures to use. Unfortunately the official test fixtures are out of my price range so I need to build some. After reading ...
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How would you find the impedance of this circuit? [closed]

I am working on a project using C++ to find the impedance of a circuit. In implementing the program I have realised that the program cannot find the impedance for a circuit of this type. My intuitive ...
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Should I use one thick wire or many thin wires in a step-up high frequency transformer to reduce resistance and impedance?

I am planning to make a step up high frequency (hundreds of kHz) transformer. I want to reduce the resistance and impedance in the secondary. Should I use one thick wire in the secondary, or should I ...
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Design challenges with high input impedance amplifier

After a couple of days of reading (also trying to find similar posts) and trial and error in my simulation tool (TINA) I see no other way than consulting you experts. In my application I have a sensor,...
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Can the frequency of voltage change throughout a circuit?

I am currently doing a project which involves taking a circuit of resistors, inductors, and capacitors (combined in any way imaginable) and finding the total impedance of the circuit. For the latter 2 ...
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Converting measured S-parameter to Z-parameter does not match the Z-parameters measured on the same circuit

I have measured the S-parameters for a 4 port circuit. For a certain frequency those values are: ...
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How to measure output impedance of this circuit?

I have the following circuit with an operational frequency range of 100 - 10kHz, always square waves. How do I measure the output impedance? I have access to an LCR meter (BK Precision 891.) Do I ...
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A non-inductive behavior in low frequency of an inductor

I have a question that has been torturing me for a while now. I cannot give you guys all the information, however, what I can say is that I have this measurement of an impedance of an electrical ...
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Homework: impedance equivalence with transformer

I am working on this homework problem and I am wondering if my approach for finding Zeq is correct. I know my matrix is correct, but I feel like I need to do something else to find the correct ...
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How to calculate the differential impedance from an s-parameter file

I have an s4p Touchstone file with a reference impedance Zr, then I think the differential impedance should be as below but I am not sure because I am not sure what the meaning of the reference ...
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Fault impedance type?

Usually fault impedances are resistive type. But is it possible to have a mix of resistive and reactive component in fault impedances? Looking at many simulation tools, they give the possibility to ...
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Question about the BJT emitter resistance

I'm trying to teach myself a little bit about BJTs, particularly through the Art of Electronics. I came across something I've been trying for days to wrap my head around. (page 92, third edition) I ...
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Independently control LEDs in series with intermediate point

I bought a bunch of LED bar arrays (DD-12 GWB KINGBRIGHT), with a relatively strange wiring diagram. I would like to control each LED. It's easy for LED A, but B and C for example are wired together. ...
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What would the output impedance of the circuit below be?

My analysis is as follows, the auxiliary amplifier with input Vb is being used to sample the output current of the main amplifier (NMOS on the bottom) and return a voltage to its gate. So it is ...
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1 answer
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What are the recommended differential trace characteristics for Power over Ethernet input section?

I've been looking through a few application notes for Power over Ethernet front ends such as Microchip AN3468 and Skyworks AN1130. I can't figure out what the characteristic impedance of the ...
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How to calculate the output impedance of an oscillator?

Is it possible to approximately calculate the output impedance of an oscillator if the rise/fall times at a given load capacitance are known, simply by using the formula for the RC time constant T = R ...
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2 answers
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Is a high resistor value between GPIO pads acceptable?

I'm designing a PCB which involves integrating two microcontrollers - an ATSAMD51 (Cortex M4)-based Arduino, and a Raspberry Pi. I need to connect a parallel bus of 10 signals between the two devices. ...
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Body voltage from stray capacitance

I've been learning about stray capacitances in my electronics module and was trying to apply the concept. If I were to hold a mains wire, consisting of a live, neutral and ground, and there were stray ...
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Small signal output impedance for a circuit with bipolar transistor?

For the following circuit, I need to find the small-signal impedance looking into the collector of the transistor at terminal X, not taking the load resistance Z into account: My attempt at a SSM is: ...
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Characteristic impedance when routing differential

Can the characteristic impedance value of a single-ended transmissions line be omitted when the two transmissions lines of a differential pair are routed differentially (not two isolated lines)? I ask ...
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Does adding a "spare" ribbon cable to a PCB increase trace impedance?

I've read numerous posts advising that trace length must be kept short on a high speed board to reduce the effects of impedance. If my traces are routed through a pin header that has an IDC ribbon ...
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-2 votes
1 answer
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Why does this method of measuring inductance work? [closed]

I recently watched this video from EEVblog showing a method of measuring inductance. I'm probably missing something obvious, but why does this work? Mathematical proof would be great. Thanks. https://...
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Transfer function for Sallen-Key notch filter

How can I find the transfer function H(s) of the following circuit by using impedance of the circuit? Should I instead do it by nodal analysis?
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Differential stripline characteristic impedance measurement

How would you measure the characteristic impedance of a differential pair (stripline) if you don't have access to a Vector Network analyzer? I have access to an oscilloscope and a signal generator. ...
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What effect does a splitting an audio signal using a y-cable have on that audio signal?

Given a clean instrument-level audio signal of reasonable amplitude passing from point A to point B via a TR/unbalanced cable, what effect would replacing that cable with a TR to dual TR cable running ...
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Voltage Follower not working for low resistance loads

I have simulated a bridge-tied load, which is to be tied to an ultrasonic transducer. The part I'm worried about is the part where the BTL touches the transducer itself. As one can see, the ...
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1 answer
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I need help understanding what the total Impedance in a delta connection is

I'm trying to upskill by teaching myself electrical engineering. I already have a degree in Theoretical physics and Pure mathematics so I don't mind math heavy answers and don't find the math's of the ...
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3 votes
2 answers
115 views

Can VSWR be complex-valued or is it always real?

This question is related to this one, but about VSWR instead of return loss: Can VSWR be complex since it is based on a complex-valued \$\Gamma\$? If VSWR is complex then it is worth noting that: \$\...
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Is there a spec for maximum voltage drop to a motor at startup?

When an induction motor starts, it pulls more current than when continuously running. Current flow causes voltage at the terminals to drop. At some point, the voltage drops too low to successfully ...
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1 answer
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What is the difference of meaning between the phase angle of S11 and the phase angle of Γ (Gamma)?

I realized recently that the Touchstone "DB" S-parameter format (.s1p, etc) uses the phase angle of \$\angle \Gamma\$ instead of \$\angle S_{11}\$ and wondered why it didn't use the phase ...
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Load impedance seen by op-amp

I have a question about the load impedance seen by an ideal op-amp output terminal in inverting configuration. When calculating the load impedance, we set Vin = 0; In one way I could say that the ...
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How can one value describe the impedance of a group of reactive components at all frequencies?

The author of the textbook containing this circuit states that the filter input and output impedance is given by: Z = (L/C)^1/2 He then shows that by setting the source and load impedance to this ...
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Help with troubleshooting a lock-in-amplifier-based impedance measuring circuit

I am attempting to use a lock in amplifier to detect changes in impedance across a small wire gap, labeled Z_p in the drawing below. I have been getting poor results, high noise, and have been ...
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1 answer
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Multiple resonances in a circuit

So I have been struggling a little to understand why when we measure the impedance of the inductance over a large frequency range multiple resonances occur. To do so, I model a 2 turns inductor in ...
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nature of the load connected to the electric power grid

I know that loads can be modeled either as constant impedance or as fixed power P and Q. I also know that the majority of the loads are constant impedance type but I don't know exactly the percentage. ...
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1 vote
1 answer
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Determining the impedance of an unknown component

If I have an antenna and I wish to measure its impedance. I have two impedance values, Z=125.52-j207.36Ohms and Z=8.14-j39.6Ohms, and I do not know which one is correct/ which one applies to this ...
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1 answer
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Creating SPICE netlist from EIS equivalnet circuits

In electrochemical impedance spectroscopy, "equivalent circuits" are often used to model the response of an electrochemical system to an AC potential input in the frequency domain. I'd like ...
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2 answers
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Can you use an inductor as a capacitor for high frequencies?

Inductors behave like capacitors at high frequencies. This is of course due to the parasitic capacitance taking over. Now, would it be possible to use an inductor as a capacitor for high-frequency ...
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1 answer
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Why is the relation between voltage ratio and frequency a linear one in a lumped transition line?

In an experiment the cutoff frequency of a lumped transmission line is determined by measuring the ratio of the output/input voltages. The lumped transmission line is a ladder network of 40 capacitors ...
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How do you build an RF device-under-test rig to create your own touchstone (s2p) files with a VNA, de-embedded to pins?

Can you calibrate a VNA to the pins of just any (low-power or passive) component and then generate an S2P to optimize an impedance match with RF simulation software to do whatever you want? If so, ...
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4 answers
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Experimental material impedance measurement

Imagine we have a square-shaped conductive material to which we connect 3 electrodes E1, E2, and E3. Suppose we assume for this material a 'pi' two-port network model with impedances Za, Zb, and Zc (...
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2 answers
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Effect of impedance on noise immunity

I read an introduction for the CMOS inverter from [1], and it mentions: "In steady state, there always exists a path with finite resistance between the output and either VDD or GND. A well-...
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2 votes
1 answer
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Do high impedance nodes have higher noise due to inductive coupling as well?

This link clearly explains how high impedance nodes are susceptible to capacitive coupling noise. Is the same true for inductive coupling? As per my understanding, inductive coupling would induce an ...
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9 votes
6 answers
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What is the difference between impedance and reactance?

I mean how are they physically different? What does it mean to have imaginary numbers in the reactance?
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