Questions tagged [impedance]

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

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Impedance matching L Network

I‘m trying to understand exactly what an L-section Network does. I understand it tries to eliminate the imaginary part of the impedance and match the real part. However I do not understand what ...
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Impedance in LTspice and current plotting

I wanted to try a test simulation on LTSpice to understand few things. I have a RLC parallel circuit and I wanted to see how the impedance varies according to each one of the components (very easy but ...
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Photodetector and low noise amplifier acting as low pass filter

I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs, https://www.thorlabs.com/drawings/275cb418cdc2cf1f-A2E46103-D9C0-3581-4553E3D3CA93AD83/DET01CFC-Manual....
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PCB antenna track and SMA connector controlled impedance

I designed a pcb for GSM module, using all the specifications given by the manufacturer, to have a controlled impedance. But there is a small detail that escapes me and that is not documented. When ...
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52 views

What am I doing wrong in finding the phase angle of power?

Consider a voltage supply \$V\angle \phi_1\$ and a circut with impedance \$Z \angle \phi_2\$. Now the Apparent power(\$S\$) is given by: $$\bar S =\frac{(\bar V)^2} {\bar Z}$$ Thus phase angle of \$S\$...
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Impedance of a Dickson Multiplier

Can someone help me in regards to calculating the impedance of a Dickson multiplier? It consists of capacitors of 3.3 pF and 2850 shottky diodes. They can be assumed ideal. It consists of 7 stages, ...
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63 views

Can I use a ferrite bead instead of a resistor on the data wire of my LED strip?

I have a WS2812B[PDF] LED strip which I want to control with the PWM0 pin (GPIO18) of my Raspberry Pi. Multiple sources highly recommend to insert a 330-470𝛀 resistor in between the data pin of the ...
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Impedance matching for broad bandwidth voltage amplifier

I need some basic advice for impedance matching: I have a photodetector (Det01CFC from Thorlabs) that generates a current. For my experiment, I would like to amplify this signal with an amplifier. The ...
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55 views

Why doesn't function generator documentation ever mention the maximum output current?

The output impedance mentioned, but how does this translate to maximum current? What happens if you short circuit the output of a function generator? Let's take the XR-2206 for example. The datasheet ...
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cmos impedance calculations

I posted a question about a week ago about impedance and have a follow up if you will indulge me. I'm comparing input and output impedance from TTL and CMOS ICs, specifically 7401 and 4011 NAND gate ...
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180 views

Xilinx FPGA and DDR3 Memory. Confusing Impedance combinations

Currently I'm planning on doing a PCB with DDR3 memory and an Artix7 FPGA. During my research a few questions accumulated. When looking at the reference manual of the Arty7 board, I see that I have to ...
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What is going on with this piece of equipment?

I am working to automate a machine to come back on after a power flicker. There are three things it needs to do when it starts up: power up, restart function A, and restart function B. Power up ...
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Help understanding the SPICE input impedance - why does it seem lower than I expect?

I am attempting to model a very simple common emitter amplifier for 144Mhz (2 meter HAM band). I found a LTSpice model for a nice RF transistor (MPSH10, 650mhz Ft) since jellybean transistors like the ...
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62 views

Meaning of complex impedance

Complex voltage and current have clear physical meaning: they represent amplitude and phase shift of a sine wave. I was wondering if complex impedance has any physical meaning as well. Can I plot it ...
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Force per velocity per time squared signifies what?

Anyone know what force per velocity per time squared signifies? It has something to do with magnetic fields. I was doing dimensional analysis and it popped up. (Charge is given units of force and the ...
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Why are capacitors high-pass / low pass frequency elements?

I'm trying to study for my intro circuits class final and always found the idea of impedance and filters confusing. Take these two circuits: The first confusion is where are we even measuring the ...
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What is the difference between high-Z (high impedance ) and open circuit?

I cannot understand exactly difference between them. I am not sure about this topic. I think high-Z means "temporarily open circuit." Can you explain the difference to me?
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CAN bus node impedance matching

Trying to understand the physical layer of CAN. Most images that I see of a CAN network has the main network bus and then nodes that come off of this bus at a T for CAN_H and CAN_L it what I commonly ...
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The equivalent inductance of a RLC in parallel

When studying a system that has the same behavior of an RLC parallel circuit, the slope of the impedance before the resonance corresponds to the value of the equivalent inductance, the slope after the ...
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40 views

Calculating output impedance without measuring open-loop output voltage of a push-pull Class AB MOSFET Amplifier

So I am building and analyzing a Class AB / push-pull amplifier implemented with MOSFET as depicted in the following schematic: R2 is the load. The input is an AC signal with 3V amplitude and 1KHz ...
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54 views

Ratio of inductance and capacitance in Colpitts Oscillator

I would like to build a Colpitts oscillator. The oscillator will have a frequency of \$f = 1/2 \pi\sqrt{C_{tot} L}\$. But what implications does my choice of \$L/C\$ have? Can I arbitrarily choose my ...
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What low output impedance of buck converter [duplicate]

The voltage mode of buck converter has a low output impedance, and peak current mode of buck converter has a high output impedance. 1.)What the benefit of low output impedance? 2.)is the high output ...
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PCB Design Review: Impedance Matching & Termination Resistors

I hope you can help review my design- I'm working on a keyboard PCB design. I thought I was nearly done, but after happening across discussions on USB impedance matching of the data traces (and ...
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4answers
148 views

AD5933 takes much longer to perform a frequency sweep than expected

I've been trying to replicate a 2015 paper that uses electrical impedance tomography to map a cross-section of a hand. They use the AD5933 bio-impedance analyzer. On page 3 of the paper, they say ...
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1answer
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Adding external bluetooth antenna with U.FL connector

I want to use this Bluetooth Module inside a metal casing. So I need a U.FL connector to add an external antenna. All I know, is that the trace from the pad to the connector needs to have 50 Ohms. ...
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impedance and resistance in phasors

Hi, so I'm a bit confused with this solution (though I'm not sure if it is correct). Why is the R in the solution 8 when the magnitude of the impedance is 10. Is this because the resistance is only ...
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Impedance Measurement (with VSA)

The impedance measurement handbook (available in more or less identical form from multiple companies / brands) recommends an auto-balancing bridge method for low-frequency (10Hz - 200 kHz) impedance ...
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3answers
101 views

Noisy AES audio signal in studio installation

This is a question about digital audio cables. I know this isn't an audio engineering forum but the question's specific to the physical connections and there's limited info online which I can find ...
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Refractive index, wavenumber, and wave impedance of the PEC that a plane wave is normally incident on

I am trying to find the refractive index \$n_t\$, wavenumber \$k_t\$, and wave impedance \$\eta_t\$ of a perfect electric conducting medium t. Here is my work so far: The conductivity of the PEC is \$...
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Art of Electronics 2nd edition p. 67, figure 2.8 — what causes the clipping?

I have been rereading this section and realized I always get hung up here. The idea of clipping happening because the emitter is not able to stay .6 or so volts less positive than the base is ...
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Clock line of SDIO bus has worse rise/fall time than rest of bus

I have an ATWILC3000 wifi module connected to a Raspberry Pi Compute Module 3+ over 4-bit SDIO. It's throwing a lot of bus errors at higher frequencies (currently running at 1 MHz for stability when ...
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Frequency of the surge voltage

When analyzing an electrical circuit, and in the occurrence of an impedance mismatch between the supply voltage and the load (connected through a cable) + a high switching frequency, reflection ...
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Simple MOSFET current mirror, Cascode Current Mirror, Impedance and Output Voltage Swing

Sorry if I don't format this exactly correct, this is my first post on this site. I am working with a simple MOSFET current mirror and a cascode current mirror and need to determine the output swing ...
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172 views

Are specific impedances for high-speed signals maintained beyond the PCB connectors?

I found this article that describes the specific impedances that single/differential traces must have for high speed signals (using microstrips). But what happens to these impedances beyond the ...
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Stuck with demonstrating effect of output impedance from EMI in SPICE simulation

The sources Vs1 and Vs2 are both measured by an ideal scope or ADC which has input impedance of 100Meg: The only difference between two sources are their output impedances 50 Ohm and 10k Ohm. My aim ...
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How do I introduce impedance in an AC circuit?

Complete noob here so please bear with me. I want to know how to and how much impedance to introduce in a single phase AC circuit of 220v and 50hz so that I can bring it down to 100v. My load is an AC ...
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Impedance inverter transformation from series lumped resonators to lambda/2 resonators

Suppose I have the following series of filter transformations beginning with a lumped element bandpass filter and concluding with shunt susceptances- The transformation from step (a) to step (b), and ...
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Simulating the capacitance of two (perfectly conducting) metal rods

I have two (perfectly conducting) metal rods (with a diameter of 10mm and a length of 150mm) which i put up (with a distance of 100mm from each other). Now I want to measure the capacitance of the two ...
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Suggestions for possible cause of impedance mismatch between board revisions?

I have a version of an 870MHz RF front-end based on the CC1190 PA/LNA based on an existing design that was ported to another PCB, manufactured and assembled for eventual use in a prototype. We'll call ...
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Impedance of an embedded microstrip with different sub- and superstrate

I have been trying to find a formula to calculate the impedance of an embedded microstrip where the substrate has a different dielectric constant to the superstrate (so the stack up is conducting ...
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Common term for Resistance and Conductance?

Simple question; Impedance and Admittance are complementary quantities, and can be described by the common term "Immittance". Likewise Resistance and Conductance are complimentary quantities,...
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Single trace width calculator for impedance matching

I would like to calculate the trace width of a dipole PCB antenna in order to match a 50ohm impedance. Obviously, there is no ground on the bottom side. All the impedance matching trace width ...
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1answer
43 views

Bio Impedance Calculator circuit

I'm currently in a project which consists of making a bio Impedance meter with the AD5933. This could be a very easy project if I had to use the frequency range (1Hz->100kHz) that give the onboard ...
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90 views

Op amp circuit and input impedance

I am trying to understand this op-amp circuit that came from one of our suppliers. The input on X9 connector is a speed sensor (magnetic pickup sensor.) Its voltage amplitude is proportionnal to a ...
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50 views

Why can you measure input and output impedance of a amplifier circuit with a resistance/potentiometer?

While running simulations for a circuit I measured the input and output impedance by simply adding a potentiometer, turn it up until the voltage peak to peak signal going out reached half and then ...
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43 views

Characteristic Impedance vs Frequency

I am reading this paper and I see that characteristic impedance does not take frequency into account. I am surprised by this as I figured different rise time signals would have different frequency ...
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How can I calculate the voltage on the load with an UNUN (unbalanced-to-unbalanced) RF transformer?

I'm having hard time calculating how much RF voltage would be applied to the load in presence of an RF transformer (Unun with a specific ratio). Let me draw a simple circuit diagram. The AC power ...
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127 views

How would I find the transfer function of this circuit?

I know that I can take the inductor and resistor and find the impedance from them in parallel. But what do I do with the resistor, R3? Do I need to do a nodal analysis and solve for the Vout? Or can I ...
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PCB trace height to width ratio

I came across the Isola IsoStack website that lets me test PCB stack-up using Isola substrates: https://www.isola-group.com/isostack My project is using a stripline design with a 1oz copper inner ...
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How to continuously vary inductance in the range \$[-A, A]\$, A>0?

I require an inductor whose inductance varies continuously as a function of some parameter \$p\$, like a bias voltage or something else that is easily user-controllable (not frequency as I require it ...

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