Questions tagged [impedance]

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

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27 views

What would be the impedance of 4x subwoofers connected with 2 on the left channel, 2 on the right channel [closed]

I want to install 4 Dayton TT25 puck subwoofers on a gaming chair for my nephew (2 on the backrest, 2 under the seat). However I can't figure out what will be the total impedance so I can choose an ...
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37 views

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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72 views

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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39 views

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
36 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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1answer
89 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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1answer
46 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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39 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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63 views

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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3answers
100 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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2answers
61 views

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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59 views

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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45 views

Initial value generator in a circuit (Anfangswertgenerator)

I am preparing for my electrical engineering exam and I saw this in my script. I have this first circuit and the requirement is to draw the circuit in Laplace with initial value generator where t > ...
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1answer
30 views

Vector Network Analyzers: Bode100 vs Keysight P5000A

I have been using Bode 100 machine earlier to measure Impedance and Phase of my piezoelectric transducer. The frequency range i work in is from 10kHz to 2.5MHz. I was just comparing this Bode100 with ...
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2answers
610 views

Pullup resistors. Does it make any difference what side of the series resistor?

The line is high frequency digital line. It has to be pulled up. Does the side of the series resistor make any difference? simulate this circuit – Schematic created using CircuitLab or ...
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85 views

Why does the length of the wire matter to the value of the pull up resistors?

In this DHT-11 datasheet the following sentence was mentioned (on page 4) A typical application circuit recommended cable length shorter than 20 meters with a 5.1K pull-up resistor when greater than ...
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1answer
36 views

Differential and single-ended input impedance

I have this circuit and I'm interested in finding both the single-ended and differential input impedance. But is there even a difference? This is also at DC, so we can just ignore the inductors and ...
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3answers
75 views

Ferrite bead isolation for FPGA core voltage

Why is the ferrite bead isolation not recommended for any FPGA core voltages. When we usually refer any FPGA schematics the voltages output from regulators are directly connect to FPGA without any ...
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1answer
53 views

How to calculate the input impedance and transfer function

I have the following circuit, that is used as a signal conditioning circuit in a audio system project. I am trying to calculate the transfer function and the Zin(input impedance) and Zout(output ...
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2answers
83 views

Maximal Cable length for a given Opamp

How can one determine the maximal cable length an Opamp can drive without getting unstable? The thing which leads me to this question is that the impedance of a cable changes over frequency. Means, a ...
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1answer
117 views

Locally hatched ground plane to increase differential impedance

I am designing a flexible PCB to carry two types of differential signals. One is about 1.2Gbps 100R differential impedance, while the other is only 3Mbps, with much more tolerance on the impedance. ...
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3answers
220 views

Input capacitor stage of ADC

I was reading the datasheet of ADS1115. It has an input capacitor stage which it continuously charges and discharges to measure the voltage between AINp and AINn. It is written in the datasheet that ...
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1answer
42 views

Cable calibration one port

The Bode 100 vector analyzer has an automatic setup to perform a one port cable calibration with short, open and 50 Ohm load, before doing impedance measurements. All good. How is that actually done? ...
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5answers
114 views

Is there a difference between PCB trace impedance and transmission line characteristic impedance?

PCB trace impedance (equations) don't seem to take into account frequency, I have (previously) been considering this to be a characteristic impedance i.e the distributed impedance of the line 'viewed' ...
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1answer
46 views

Shift and reduce sinewave

I want to meausure the impedance of a sample of carbon, marked Rc in my drawing. On my FPGA I have a DAC which can provide 0-3 volts and an ADC that can read 0-3 volts. By reffering the positive input ...
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59 views

Impedance Equalization Circuit

With reference to the circuit on attached -- the zobel/ impedance equalization circuit. If we don't know the value of L, Is there any ways to calculate C' without knowing the value of L? I believe ...
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192 views

CAN Bus on PCB traces instead of twisted pair cable - points to consider

In order to save cost on the system in one of my current projects (no cables) I would like to eliminate the CAN cable and add traces to the PCB (one pair from left to right to connect the connectors + ...
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53 views

Not matching 50 ohm impedance

For my RF circuit (868MHz), I need 50-ohm impedance. When I calculate the impedance as PCB manufacturer layer stack-up, the impedance would be 66 ohms. How does this affect my RF circuit performance? ...
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39 views

Digital output drive signal integrity

I am designing a PCB with the ICS-43434, and would like to do, at least, some simple signal integrity simulations. I asked the manufacturer for impedance, IBIS or V/I curves, but they do not have that ...
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1answer
57 views

RF Matching Net

I am projecting a system that contains two RF chips, a LoRa SX1276 (915MHz) chip and a ESP32-D0WDQ6 (2.5GHz). In the schematic bellow, the ESP32 (2.4GHz) design has a matching net between the chip ...
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89 views

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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1answer
92 views

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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3answers
65 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
56 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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36 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
109 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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68 views

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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56 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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94 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
56 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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2answers
87 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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3answers
109 views

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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5k views

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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94 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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50 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
69 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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86 views

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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2k views

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
59 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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