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

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Input and Output Impedances In Transistor Configurations [closed]

Why does a common base configuration have low input impedance and high output impedance ? And Why does a common collector configuration have high input impedance and low output impedance ?
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64 views

Solving three impedances in series

I have a circuit of two capacitors and three resitors, where two pairs of the components are in parallel combinations: I'm trying to calculate the total impedance. Since \$C_1\$ and \$R_1\$ are in ...
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82 views

How to realize a zero at infinity ? RC synthesis

I'm just trying to synthesize this bellow pole-zero map. Since now I have come up with the following equation. $$Z(s) = \frac{(s+1)(s+3)}{(s+2)(s)} $$ But I have no idea about how could I ...
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1answer
58 views

Input impedance of a transistor amplifier from an example

Going on reading "The Art of Electronics", I am still stuck on another input impedance calculation for a transistor amplifier. This is really something I should overcome, maybe your explications will ...
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1answer
50 views

Impedance Matching Resistor

I'm working on a high speed ADC/DAC board. I saw some reference designs for the device, there are matching series resistors connected between output digital pins & controller. Though, resistor ...
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1answer
71 views

Microphone output resistance, why this value?

I would like to sample the output of a microphone. I am using the following set-up in order to tune the DC offset at the microphone output. simulate this circuit – Schematic created ...
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27 views

Picking the right tool to trust for impedance calculations

I'm having a dilemma, when I'm creating layer stackup for my boards I'm in a situation where my tools (Altium, ICD stackup planner, online calculators) and even my PCB manufacturer do not necessarily ...
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3answers
192 views

Input resistance of a transistor circuit

I have a question from the razavi's microelectronics book: I'm puzzled because in the solution provided, the first line states that: "We know that the input resistance Rin = R1||R2||\$r_π\$." ...
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36 views

Impedance problem (polar to rectangular)

Having a little problem understanding why this example converted polar to rectangular form to get Z. What is wrong with just leaving it in polar form and doing the algebra to get the value for Z
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43 views

Xilinx Spartan3-E FPGA input impedance and input leakage current for the GPIO pins

I am trying to use one of SPARTAN3-E FPGA GPIO pin as an input to ADC. I want to know the input impedance and the leakage current for GPIO? Should I just connect my circuit's Vout to GPIO pin or ...
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2answers
61 views

Door phone audio signal to pc soundcard

I need to interface door phone system to a pc soundcard to listen and talk to the external unit. The door phone to interface is an as yc/200 of BPT and its a classic analog 4+n wires Door phone ...
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2answers
76 views

Does impedance discontinuity distance matter?

I'm not remembering my education very well. I know when a signal encounters an impedance discontinuity there will be some reflection, I just want to know if in my case that is a practical concern. I ...
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91 views

Automatic impedance matching in microwave waveguides

I am trying to building a magnetron plasma using microwave magnetron. I now need to build magnetron to antenna link using rectangular waveguide, WR-340. I then found out that it needs to be tuned ...
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100 views

Take the voltage out of a voltage divider with no distortion

In the (simplified) schematics below, I would like to measure the voltage at point A with an instrument that I have to plug at point B. The problem is that if I simply add a wire between A and B, ...
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1answer
59 views

Why single-ended pcb trace impedance is fixed to 50ohms [duplicate]

Why is the trace impedance of a single-ended trace on a PCB fixed to 50 ohms or 75 ohms (for video signals)? Why can't it be fixed to any other impedance values?
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68 views

Voltage Reference Output Impedance

Relevant Datasheets: AS431 Voltage Reference INA126 Instrumentation Amplifier I am designing a circuit which will amplify a few millivolt input (~+/-10mV full range) to a few volts (~0-8V output, ...
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17 views

Influence of a Capacitance Matrix of a voltage measurment

I am having a problem in understanding how, in a multiconductor system, the Capacitance Matrix influences the measure of voltage between two electrodes. In the case that interest me we have 4 ...
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2answers
64 views

How to set the input impedance of an inverting amplifier

I want to Design an op-amp inverting amplifier circuit with Closed-loop voltage gain = -10 and Input impedance = 10k Since the it's an inverting amplifier then the Closed-loop voltage gain =-Rf/Rin ...
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1answer
76 views

Is it possible to design this circuit with a single potentiometer (L-pad)?

I'm designing an L-Pad for my speakers. They attenuate the signal while keeping a consistent effective impedance, which is necessary for the amplifier and crossover circuits. Typically, these values ...
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3answers
94 views

The contradictions in relation between current and voltage with regards to power and impedence

What happens in a house if there is a change in voltage due to voltage fluctuations? assume voltage decreases from its normal value case 1) V = I*Z Z does not change unless there is a change in ...
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400 views

How is xΩ impedance cable defined?

This is probably a really simple question, but I can't seem to find a definite answer anywhere. I'm guessing 50Ω cable means 50Ω per unit length. What unit length is this? If this is not how its ...
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3answers
130 views

How to measure headphone impedance for a target cut off frequency?

Lets say I have an audio signal with a DC offset and I want to use my earplugs to listen it clearly. Since I'm a human my hearing range is 20Hz to 20kHz. It means I need to filter very low frequency ...
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1answer
109 views

Linear Transformer and Ideal Transformer: electric circuit question

The question is to determine k in so that no current flows in Zx. I literally have no clue how to start. If there is no current in \$Z_x\$ that would make it an open circuit, so for it to be ...
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95 views

Why does this parallel->series rewrite change my AC simulation results a little?

Here are two circuits I've simulated. Both have a current source of \$\sin(\omega t)\$ mA with \$\omega=1000\$. They should be equivalent but give different simulation results. Here are the ...
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4answers
433 views

How are speakers matched with audio amplifiers? (avoiding overloading either)

I know a similar question title has been asked, but I believe that does not answer my question (and I couldn't think of a better way to phrase the question). I'm a bit confused by how exactly an amp ...
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2answers
96 views

About impedance matching for high frequency and divider effect

----- 2013/11/08 modify my question I have an 'A' source has 5 MHz signal (0-5 V square wave) without knowing input impedance and a receiver 'B' has 75 ohm input impedance. As I know I have to match ...
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128 views

What does it mean for an input impedance to be “differential”?

In a specs of a data acq. device the input impedance is shown as "20 MΩ differential". Does that mean the measured impedance in diff input case? If so how can I calculate the input impedance for ...
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92 views

Correct calculation of conductance/susceptane and from there to admittance, impedance, resistance and reactance.

I am sending a sine wave through a unknown RC circuit. At the other side I have a current-to-voltage converter (transimpedance amplifier) measuring the current indirectly as voltage. I am using IQ ...
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1answer
74 views

Designing a purely reactive circuit with the following requirements

how would you design a purely reactive circuit with: Infinite impedance in f = 0 Hz and f = 800 Hz Zero impedance in f = 5000 Hz and 11000 Hz At 7000 Hz, has a reactance of 181.85 Ohms How to proceed ...
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1answer
102 views

Calculating voltage in RLC circuit

Well I think the prof has made a mistake in one of his exercises, though asking here to be sure, The question is to calculate the supply voltage in the system below. simulate this circuit ...
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1answer
80 views

What does negative impedance mean in the context of miller's theorem

Miller's theorem states that for a linear circuit of two nodes with voltages $$V_1,V_2 $$ which are connected by an impedance, $$Z$$in series, circuit could be represented by an equivalent one with ...
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1answer
159 views

what's the purpose of this transistor setup (answer: simulate an inductance)

I encounter the following block in three regions of an Altec Lansing APT3 2.1 speaker system. simulate this circuit – Schematic created using CircuitLab Given that VH = 9V D.C., I only ...
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219 views

Why does this circuit oscillate?

The circuit below is an oscillator. When I simulate it with ltspice, it does indeed generate a waveform (although it doesn't seem to be a very pure sine wave). What I fail to understand is why it ...
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323 views

Behavior of capacitor with infinite capacitance at steady state (DC analysis & AC Analysis)

What is the behavior of the capacitor below at steady state (DC/AC Analysis)? simulate this circuit – Schematic created using CircuitLab
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262 views

Why are high impedance circuits more sensitive to noise?

Why are high impedance circuits being more sensitive to the noise? They have less current flowing through them, but how is that related to noise, since external noise becomes voltage on the wires, and ...
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54 views

ADC Input Stage Impedance

I plan to use the TI ADS1178 (datasheet) ADC. The ADC specifies a "Differential Input Impedance" = 140kOhms (low-power mode). Would this input impedance be the same for single ended inputs when using ...
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1answer
176 views

Derivation of Characteristic Impedance?

I start from the telegrapher's equation: \$-\frac{dV(z)}{dz}=(R'+j\omega L')I(z)\$, where \$V(z)\$ and \$I(z)\$ are the phasors of voltage and current respectively, in the transmission line model. ...
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80 views

Transformer circuit, equivalent impedance

Having trouble with a circuit on my problem set and was wondering if anyone wanted to give me a push. The ideal transformers winding relationship N1/N2 can be varied, as can the capacitance. Decide ...
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1answer
92 views

Different voltages with Ferrite Beads

I am checking the datasheet of one complex component, and the schematics of one demo board, and I find a difference that I would like to ask here. It is a 100Base-tx switch. The chip uses 3.3v for ...
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1answer
253 views

1W Push-Pull Power Amp Design

I need a simple single supply amplifier that draws a lot of current when signal is applied. Without going into why, let's just say this is supposed to be part of a compressor. Distortion performance ...
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1answer
391 views

Reflecting impedance in a transformer

Please can anyone tell me what exactly is meant by reflecting of impedance in a transformer? I do not know much about transformers, but I want to know about its uses and phenomena behind it. I will ...
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1answer
421 views

How do I determine the inductance of a circuit using Op-amps, Capacitors and Resistors?

I am trying to prove that the inductance of a given circuit (between the source A, and ground) (see image below) is equal to (R1*R2*R4*C)/R3. Under the assumption that it is an ideal op-amp, I know ...
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47 views

How would one determine the impedance of a catenary end-fed antenna?

I'm thinking of having a weather balloon haul high-gauge (35SWG or higher) antenna. Then play with using it atleast for reception on the long waves. The wire certainly won't be vertical; I expect it ...
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1answer
96 views

Formula for finding the magnitude of the impedance of a ratio z = (x+jw)/(a+jb) [closed]

How do I calculate the magnitude of the impedance of the following ratio, \$z\$? $$z=\frac{x+jw}{a+jb}$$
3
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1answer
356 views

Complex Dummy Speaker Load Impedance

I would like to create a dummy load for this so-called "Deacy Amp": This is a low power germanium transistor / transformer driven push-pull amplifier for driving a small 4 ohm or 3.2 ohm speaker. ...
22
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4answers
3k views

How can PCB trace have 50 ohm impedance regardless of length and signal frequency?

Hmm, this seems to be just another question on line impedances. I understand that when we say "transmission line" effects we talk about things like cross talk, reflections and ringing (I guess that ...
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105 views

looking for highly accurate phase detector

I'm looking for a highly accurate phase detector for my capacitive sensing application. In the application, the capacitance is in the range of 1 ~ 10 pF. I've been able to get the capacitance via ...
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2answers
309 views

Coaxial cable, resistor and oscilloscope

I'm studying the trasmission of signals though coaxial cable; I'm using a coaxial cable (of course!), an oscilloscope, a generator an some different endings. This is the scheme: I was told that if I ...
6
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2answers
202 views

Do the logic gate inputs of 74HCXX integrated circuits exhibit a high impedance?

Do the inputs of the 74HC374-SMD D-type flip flop have high impedance inputs? In datasheet is stated that it has buffered inputs, I assume that means high impedance, right? In other words, do I have ...
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2answers
6k views

What is input and output impedance of an opamp?

I have never understood input and output impedances of an op-amp. If anyone can explain what these two terms mean in an op-amp I'd highly appreciate it. Thank you! ...