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Questions tagged [impedance]

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

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41 views

Question about Complex power [on hold]

Can anyone solve this question. What mean by no phase shift.This is about Complex power.
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1answer
48 views

Output impedance of a series shunt feedback amplifier

I am trying to find the output impedance of a series shunt feedback amplifier by converting it to a two port network. I know the input impedance: Ri=ri*(1+A.β) But I dont know how I should find ...
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33 views

Input impedance calculation - antenna + transmission line [closed]

Question: If an antenna with an input impedance of Z(a) = (50-j10) Ω is connected to a 50 Ω transmission line of length 1λ. What is their input impedance? Here is my attempted solution: Is it ...
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1answer
61 views

At what frequency is a transformers rated impedance measured

Where transformers have a specific impedance rating for the the primary/secondary, what frequency is this measured at? For example, this transformer is rated at 40MHz - 860MHz with an impedance of 50/...
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1answer
30 views

Impedance matching of USB device WITHOUT cable

If I understood correctly, when designing PCB with USB, the 90-ohm differential pair of D+/D- trace if for matching the USB cable differential impedance. Otherwise, there will be a signal reflection ...
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3answers
108 views

Why are piezoelectric sensors called high impedance?

Piezoelectric mics and accelerometers are called high impedance aka high Z sensors. And I know that the high impedance sensor output needs to be converted into a low impedance signal first. I think ...
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55 views

Electronics - Input and Output Impedance

I know how to analyze circuits but I'm stuck in this problem about input and output impedance. What is that and how are they calculated?
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1answer
47 views

Impedance determination of blackbox circuit

I've been looking into something and I'm not entirely sure how this is done. So I was looking at how they determine the parasitic and resistive components in pv panels, it looks like the majority of ...
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1answer
80 views

Physical intepretation of the absolute value of impedance [duplicate]

If \$\rm{Re}( Z)\$ gives the reactance of a circuit, then what is the physical meaning of \$|Z|\$? How do they differ, and when would one use one over the other? (Where \$Z\$ is the impedance of an ...
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1answer
48 views

How to determine the best resistance for a weak signal Twin-T notch filter?

I am designing a 50/60 Hz Twin-T notch filter for a weak (biomedical) signal output from an instrument amplifier (InAmp) to be chained to another active low pass ...
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1answer
45 views

Measurement of output impedance (ro) of a modified wilson current mirror

How do I measure the small signal output impedance (ro) of a modified wilson current mirror? example Q4:
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1answer
37 views

Power Contours for a Power Amplifier

I am having a bit of difficulty generating the power contours at a Pin where Pout is 17dBm. I am doing a PSS analysis in Cadence Virtuoso. I am sweeping the phase along with a parametric sweep of the ...
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2answers
63 views

Z=50 and Xs=0 but SWR is not 1.0:1

I measured an antenna with a VNA and differently to all other cases the SWR isn't low as expected. Here are some screenshot showing this: Similar situation, on the same antenna in the same ...
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79 views

A question on the meaning and model of microphone impedance

I’m a little perplexed by the circuit model and meaning of a high or low impedance microphone. Here is an example where someone at this page is trying to investigate the effects of low or high mic ...
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1answer
78 views

Can the output impedance on af op-amp be set to 50 ohm regardless of frequency?

I want to make a circuit with an output impedance of 50 ohms. I am dealing with negative photomultiplier tube pulses that in 50 ohm load look like in the picture below: I want to use the pulses to ...
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2answers
68 views

Accelerometer Sensor Output Impedance

I am looking into purchasing a TE 810M1 Accelerometer and had a question regarding the resistor's value for amplifying the sensors output. Here is a photo of the sensors electrical properties: The ...
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2answers
66 views

Impedance matching and reflection

I have a simple question about reflection and impedance matching. Consider a voltage generator Vg with its output impedance Zg, and suppose it drives a load Zl. In order not to have reflection, we ...
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1answer
60 views

Bulk current injection - Resonant frequency of ESD protection diode CAN bus

Link to the application note that I'm referring to below. I was going through an application note by On Semi, System Level Surge Suppression Solutions for the CAN Bus -AND8253/D, where it says that ...
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1answer
73 views

Measure impedance of rectifier using harmonic balance in ADS software

I am trying to use harmonic balance to find the impedance of the voltage double rectifier. After finding the impedance, I will use the impedance matching tool to find out the L matching. As the ...
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2answers
40 views

Impedance frequency response for a DC motor

Consider the following impedance frequency response for a DC motor : Its equivalent circuit is : Clearly, from the response, there exists a capacitor, inductor, and resistor, but my problem is how ...
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119 views

Determining Output Resistance of Transresistance Amplifier

I'm really inexperienced when it comes to operational amplifiers, but I'm trying my best to learn more about them. That being said, I'm currently having trouble understanding the transresistance ...
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36 views

Impedance Matching and Reflection Coefficient

Consider a real signal generator (Voltage Source Vs, output impedance Zs, reflection coefficient Γs) and a load Zl with reflection coefficient Γl. I was told that we have maximum power transfer when ...
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2answers
36 views

Impedance frequency response

Consider the following the frequency response of the impedance of a resistor component : We know that a resistor has a parasitic capacitance and inductance due to its leads. So the impedance of the ...
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1answer
533 views

Why did CATV standarize in 75 ohms and everyone else in 50?

All of the CATV industry runs on 75 ohm systems, while most of the rest of the radio world uses 50 ohms. Why was this standard chosen? I was wondering this because good quality RG6 cable can be ...
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1answer
63 views

Arriving at a wrong output impedance for a BJT Emitter Follower Configuration Circuit

We've to calculate output impedance of the circuit (figure 1). Although i understood the textbook solution (figure 2, figure 3), I took a different approach and arrived at a wrong answer. step 1: I ...
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63 views

What does line impedance stabilization mean?

What exactly does line impedance stabilization mean? What parameters of line impedance are stabilized and how? How does line impedance / source impedance vary with frequency?
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48 views

Question about 50ohm impedance matching circuit

I am implementing rf energy harvesting circuit. The rectenna is working at 915MHz and the impedance is 50Ω. I think L-matching may be the easiest. However, I don't have the vector network analyzer. Is ...
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1answer
175 views

Impedance calculation from voltage and current (exponential) waveforms

If we want to find the impedance across two terminals (a port) at a frequency \$\omega_0\$ using the voltage waveform across \$v(t)\$) and current through (\$i(t)\$) the terminal, general intuition is ...
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80 views

Smith chart of λ/4 Transmission Line

I came across the following slide on power combiner circuit and I have questions about it. Why traverse across the upper half circle ? Why "ZT-line is the geometric mean of Zout and Zin." ?
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220 views

Converting a headphone output to line level

I have a guitar amp that has a headphone output. I would like to convert this signal to line level so I can use it in a small mixer along with other line level signals to be heard in "in ear" style ...
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3answers
1k views

Strange opamp's output impedance in spice

I'm simulating this circuit in Micro-Cap, which is the clipping stage of a guitar effect. The opamp model is the "NE-5532" I want to measure the input and the output impedance. I expected an output ...
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2answers
199 views

How to achieve 100ohm impedance for HDMI differential pair on FR4?

I have a 6 layer FR4 PCB, and want to achieve 100ohm impedance on HDMI differential pairs. I am only using top and bottom layer for differential pairs, and following are my parameters: Trace width= 3....
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1answer
59 views

Impedance/capacitance measurements

I'm trying to do some impedance measurements on passive components with the simple circuit shown below. I find it difficult to make sense of the results and hope somebody can help me understand what I'...
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2answers
78 views

Any equivalent load circuit when an animal is connected to a current injector?

When the human body (chest, arm, etc) or an animal (limbs, belly, tail, etc) is connected to a circuit, I think this acts as a load. For instance, people simply model the connection between the AED (...
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3answers
92 views

What does input/output resistance/impedance mean?

This keeps coming back in every single class, and I still don't have a clear idea of what it is. I keep seeing certain statements in other explanations such as "seen by X", "looking into Y" and so on. ...
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55 views

How to convert this single ended output to a precise impedance balanced output?

This amplifier suits my purpose with one matter that I couldn’t figure out. Its output impedance is given as 0.01 Ohm. The output of this amplifier will be coupled to a very high input impedance(more ...
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3answers
116 views

Is high current in a speaker the same as high voltage?

I'd like to build my own Amplifier, and because I know that the current creates the magnetic field, I don't understand, how amplifying the voltage makes it louder. I mean with high voltage doesn't ...
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1answer
93 views

Passive band-pass filter conceptual analysis

I'm trying to chain a high-pass filter and a low-pass passive filter together to form a band pass filter to illustrate how you can combine filters together, but I'm having issues trying to understand ...
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33 views

Calculating voltage loss using impedance of a system

simulate this circuit – Schematic created using CircuitLab So I'm trying to figure out the Total impedance Z of a system with a capacitor in series with a resistor and inductor, where the ...
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1answer
29 views

Confusion between Input/Ouput Impedance and Thévenin's theorem

I'm bit confused about what Input Impedance or Output Impedance is. I tried to read Wikipedia's page (https://en.wikipedia.org/wiki/Input_impedance) but I find it hard to follow. Is the Input ...
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1answer
43 views

Cut-Off Sinusoid or Sinuosoid?? - Standing Voltage Waves on Transmission Lines

My textbook shows two diagrams that appear to contradict each other to me. Each depict the magnitude of the standing voltage waves on a transmission line. The first, fig 2-14, shows a sinusoid bounded ...
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24 views

Output TX Power with complex impedances

I'm developing an application with my software defined radio (SDR) Board and it is very critical that I have some control over the actual power I am transmitting at every time. In order to do this, I ...
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1answer
114 views

Difference b/w Symmetric and Reciprocal Networks

A circuit exhibits symmetry when interchanging ports across a plane of symmetry results in no change in the impedance, admittance or scattering parameters of the circuit. Reciprocity also means ...
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2answers
157 views

How do transformer obey Ohm's law?

I am honestly confused, A transformer "Steps up the voltage and steps down the current" or vice versa. So how does it obey Ohm's law? for example, a transformer with a winding relation of 2:3, should ...
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54 views

Can I connect a 16 ohm output signal to a line input if I use a resistor in series?

newbie here. I have a Hi-Fi system and I wish to connect its output to a line input in another system while still being able to hear through the Hi-Fi´s original speakers. If I use the Headphone ...
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2answers
57 views

Low-impedance tap in this oscillator circuit

Here is the schematic of Michigan Mighty Mite, a popular transmitter circuit design. It seems to be quite close to a regular feedback oscillator, with a few peculiarities. What puzzles me is the ...
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1answer
63 views

How to quantify the cable impedance for common mode voltages?

Since a coaxial cable is not twisted, in the case of a common-mode interference the positive and negative lines will pick up different voltages. This unbalanced impedance nature of the cable can be ...
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2answers
175 views

Controlled Traces Length in SD card

I my new design I need to use SD card communication. I would like to match all the impedance traces and control the length of the traces. Regarding the controlled length, is there a rule of thumb to ...
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1answer
172 views

Induction heating

I was reading the working principles of induction heating and I think I understand the basics. Out of curiosity, I searched the Internet for a schematic and found one. However, the thing that confuses ...
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2answers
58 views

Problem understanding impedance measurement device accuracy format

I am reading the datasheet of an impedance measurement device. Its accuracy is listed as '±0.4% rdg. ±8 dgt.'. What does 'rdg.' and 'dgt.' mean? And how should I interpret the accuracy? The device is ...