Questions tagged [impedance]
Impedance defines the voltage/current characteristic of any dipole circuit.
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What is the resonant frequency?
I know the formula of resonance frequency for both series and parallel circuits. But when we have a circuit that is shown in the image below where the RESISTOR and INDUCTOR are in parallel and their ...
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CAN-Bus: Wire Impedance vs Terminal Resistor
I'm seeing several pre-fabricated "CAN-Bus" cables with (2) DB9, 120 ohm terminal resistor connections, while the cable's impedance is 100 ohms.
A. What is the purpose for this mismatch?
B. ...
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USB-C board layout question
I have a board design that uses an Amphenol rugged USB-C socket to feed a Microchip USB5744 USB3 hub. When laying out the tracks, it struck me that the 'unused' Superspeed inputs are like stubs on the ...
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Input impedance of a round straight copper antenna
I got some help from a discussion of yesterday about network impedance matching for transferring data between antennas (Basic RF signal amplifier). The discussion was about that the current and the ...
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Impedance reflection in making a simple current source
I am making a constant current source using the transistor. I am a bit confused regarding the biasing of the transistor. I have seen in many places that when we are setting the biasing of the ...
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Value of a ferrite bead in PHYs
I have seen a couple of ethernet PHYs whose manufacturer datasheet recommends placing a ferrite bead on the power supply input of the PHY device whose value is, "Generally, a 100-220Ω (at 100 MHz)...
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Common Emitter small signal model for high frequencies simplification
While trying to calculate the high frequency pole frequency corner of the common emitter amplifier I came across the following small signal model (found here in page 332)
The small signal equivalent ...
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Frequency Range VI(Labview)
I tried to understand what "Frequency range vi" consists. But I didn't understand.
From Reference Article(doi:10.15199/48.2021.11.10): No.1 shows the block diagrams of fixed-point data ...
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PCIe "RefClk" impedance requirements?
I'm designing a very heavy impedance-requiremented PCB, with PCIe v2.
I know TX and RX diffpairs have strict differential ...
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Impedance-critical diff-pair routing
I need to route PCIe RX and TX diffpairs:
I can't change the bottom connector (fits into M.2 KeyE socket), neither the top (M.2 KeyM socket).
Normally, how shall I wire these diffpairs?
It seems I ...
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Differential impedance calculation - which way to go width vs spacing?
In USB2.0 specification, there is a requirement of desigining its data traces to be around 90Ohms +/- 15%.
Using this calculator, based on my earlier question I'll need to make sure to approach 90Ohms ...
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Which impedance matters?
In USB2.0 specification, there is a requirement of desigining its data traces to be around 90Ohms +/- 15%.
Using this calculator, with these below data:
I got these results:
Now, question is, which ...
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Arc-shape frequency dependence of phase angle in bioimpedance spectroscopy
I have concerned myself with bioimpedance spectroscopy (BIS) from a medical standpoint for some time now, however there is one concept evading my grasp until now:
When measuring complex impedance of ...
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Capacitance for which the ratio of the input and output voltage is independent from the frequency
I have the following circuit with resistors and capacitors in parallel (see Picture 1):
I have to determine the capacitance \$ C_1 \$ in such way that \$\frac{u_e}{u_a} = 1 + \frac{Z_1}{Z_2} \$ is ...
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Total impedance in a circuit
To determine the current I have to calculate the total impedance, here named \$Z_{Ges}\$, in the circuit which can be seen in the first picture.
First I summed \$R_1 \$, \$C \$ and \$R_2 \$ as a ...
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Impedance matching on RF PCB
I have two questions about a power amplifier board, see picture.
The output of the amplifier has irregular copper traces with different lengths to the output SMA, which I marked (1). Doesn't this ...
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New ESP32-D0WD-V3 based board has WiFi issues in transmit; receive is OK
I have a custom board with the above chip, and it all works except for the WiFi transmit functionality. I can receive fine with -60 RSSI from my AP 50 meters away, and I receive all my neighbours' ...
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If the impedance of two coils is measured to be identical at 250.0 kHz, is it safe to assume identical impedance across the spectrum?
This question pertains to matching two air-gap inductors for use in resonant coupling. Alternative solutions are welcomed and appreciated.
The two coils shall be comprised of identical wire.
The two ...
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Output impedance of small-signal model
When I calculate the output impedance (Rout) of this small signal model, do I have to short circuit between 2 ends of the blue wire or black wire?
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Band-pass RC filter design understanding
SO i came across an exercise question in a book
Design a two-stage “bandpass” RC filter, in which
the first stage is highpass with a breakpoint of 100 Hz, and the
second stage is lowpass with a ...
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How to find driving point impedance of non-inverting op-amp circuit
I have this circuit:
And I am asked to find the driving point impedance.
I know that a driving-point impedance relates the voltage and current at a pair of terminals. The formula for the driving-...
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How to derive transistor input impedance?
Given the following circuit,
When Ro is not infinite, from the book, ZB is given as,
However, when it's infinite, the input impedance is easily obtained as the parallel combination of RB and β(re+RE)...
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Transfer function of non-inverting op-amp circuit
I have this circuit:
I am asked to show that the transfer functions of the circuit is:
I know that for non-inverting op-amps:
\$ Z_{in}=\infty \$
\$ Z_{out}=0 \$
\$ H(s)=\frac{V_{out}(s)}{V_{in}(s)} ...
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Need help using RF transceiver with RF amplifiers
I'm trying to use the STM32WLE5C8 SoC that is both a microcontroller and an RF radio.
For my project I will be using the radio in the 800 - 900 MHz band (high-band configuration for this radio).
I ...
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50 Ω or high-Z setting on waveform generator?
I have an arbitrary waveform generator that allows me to set the load as 50 Ω or high-Z.
This generator is connected to an amplifier that has as input an unbalanced BNC connector, 10 kΩ, single-ended.
...
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How to convert Thévenin equivalent to Norton equivalent in this schematic?
I am learning the bus admittance matrix from Power System Analysis by Hadi Saadat electrical engineering. I have a very big problem in chapter 6.2 - Bus Admittance Matrix.
At the beginning of chapter ...
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Finding an analytical expression for a current distribution for conductors in parallel
Recently, I tried to set up an experiment at home to study what path the current takes at different frequencies for the circuit below. I think this will be a fun project, but I'll need your help.
I ...
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How do I design a cascade of op-amps in terms of high impedance?
An operational amplifier has a high-impedance input. That means that its current consumption would be really small, so, we can say it can measure voltage without affecting the circuit in terms of ...
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What does degree in a schematic mean when drawing a PCB?
I am designing a PCB for LNA with an SPF5189z. I found a reference schematic design in the SPF5189z datasheet:
(Image excerpted from the previously linked datasheet.)
What do they mean by those ...
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Transformer being shorted and opened
For a perfect transformer, 1:1 turns ratio, V1=V2, I1=I2. Z1=V1/I1. Z2=V2/I2. => Z1=Z2.
When I keep the 2nd coil open circuit, Z2 is infinite. Since Z1=Z2=infinite, if I apply perfect AC voltage ...
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Amorphous Silica Electrical Impedance Tomography
I would like to see if the idea I have for an experiment is even worth the effort and money to perform. I would like to use electrical impedance tomography to image a developed thin layer ...
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Antenna input impedance calculation
I am attempting to calculate an antenna's input impedance. I have been given this information:
A 50 Ω coaxial line is feeding the antenna a 150 MHz frequency. It has a dielectric constant of 2.25, ...
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Complex number or absolute number for impedance
I am reading about high speed PCB layout design from TI (Texas pdf)
This document mentioned the software AppCAD from Agilent to calculate impedance. Here is the snapshot.
My question here is whether ...
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Controlled impedance stackup questions
In this stackup (I know that it is not the best stackup but it is a general question,) if I choose to use controlled impedance on L4 (let's say 50 ohm), what is the ...
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What is the difference between these two input impedance equations?
I'm currently solving some university E&M homework problems and to solve input impedance, we were given this formula (from Fundamentals of Applied Electromagnetics 6th Ed):
But when I browse ...
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Negative resistance circuit stability
Assume we have this circuit:
simulate this circuit – Schematic created using CircuitLab
Which will be the current flowing in such a circuit.Can we say that the resistors are in resonance?(...
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Complex voltage and current
Someone can explain me the phenomena in rlc circuit. If we have an input voltage \$V_e = V_{max}\sin(wt)\$. Why the current resulting when it is written in books is not a complex number? And why the ...
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RF design_output impedance of the SX1280 LoRa transceiver
I searched the datasheet of the Semtech SX1280, but I can't find the output impedance of the SX1280 (RFIO's pin). Where can I find it?
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Impedance matching 133 MHz - Topology and terminating resistor concerns
I am using the QSPI bus of the RP2040 to talk to a flash chip. I am also putting 8 more chips (PSRAMs) on that bus in my design, and a second RP2040 to load them. The datasheet for the RP2040 isn't ...
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AC - impedance for a coaxial cable
Problem
I want to calculate the AC impedance for a coaxial cable. A rough image is presented below:
Because we have an AC current, suppose that the skin depth, which we can define as \$\delta\$ is ...
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Ferrite bead or inductor
I'm using this device VSC8514 and this is its checklist.
I just want to know what spec of ferrite bead I should use for this device's power rails.
They have neither mentioned this in the checklist nor ...
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What is blocking impedance (specifically in a substation)
Can someone please explain what blocking impedance means when it comes to discussion of wave traps in a substation. I always see the blocking impedance listed as either 1000 ohms blocking or 400 ohms ...
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UHF RFID antenna
When designing a UHF RFID antenna, besides matching to the chip, is there some matching to air that needs to be done (for example, to the characteristic 377 Ω)?
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Relative short-circuit impedance of a three-phase transformer
I am trying to calculate the (absolute) short-circuit impedance from the relative short-circuit impedance of a three-phase transformer. I am not sure if my formula is correct, especially concerning \$\...
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Crystal resonator characterization in frequency and time domain
I want to measure a 32.768 kHz crystal resonator (not oscillator) in the frequency and the time domain using a ZURICH HF2LI instrument, which is a network analyzer and oscilloscope in one unit.
The ...
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Output impedance of the circuit
I would like to know what the output impedance of this circuit is (the impedance seen by the node output).
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Frequency response of LC filter with resistance in parallel with the capacitor
The following is the diagram of interest:
The impedance of the filter is:
$$Z_o=\frac{R_f L_f s}{R_f L_f C_f s^2+L_f s+R_f}$$
and the bode plot with all different components and the total impedance ...
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Input impedance of an electronic load
I would like to simulate a TVS with an electronic load working in constant voltage. I could add some resistor in serie with the electronic load to simulate the dynamic resistor of the TVS. ...
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Impedance Measurement Point
I've been doing some work with interstage impedance and I keep getting confused and I can't seem to get the correct answer myself. I know Input Impedance should be 10x the amount of the previous ...
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Finding the value of supply voltage in this RLC circuit
We need to find the value of V, Power Factor, and Power Absorbed in the circuit.
I am stuck at resolving the two parallel branches.
I started out by labeling the impedances of the three given ...
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