# Questions tagged [impedance]

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

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67 views

### Understanding Impedence [closed]

I'm a Computer Programmer and learning Electronics , It has been difficult for me to understand concept of Impedance still , Is there any good Article or Lecture serious which help to understand from ...
17 views

### Power consumption on LPDDR4 command bus - impedance options

I'm trying to solicit and opinion on the use of the 60 ohm transmitter/transmission line/ODT for the command bus of an LPDDR4 bus would be better than 40 ohm target impedance. The system uses an ...
28 views

### RCL circuit sum

Just need help in the daigram of this sum. Can't understand the daigram.will a common resistance be shared between capacitor and inductor or is there 2 resistor and 1 capacitor and inductor with ...
185 views

### Wien Bridge Oscillator: Why does equating the real part to 0 give the gain equation?

I am learning about Wien bridge oscillators. Following Experiment No. 9: WIEN BRIDGE OSCILLATOR USING OPAMP, they use the following schematic: They then arrive at the following equation half-way down ...
36 views

### How do I incorporate output and input impedances connected to my circuit?

I'm designing a TTL to VGA DAC for a vintage PC, and I'm confused about the significance of the output and input impedances of my video card and monitor, respectively. The VGA spec states 75 ohms at ...
574 views

### Parallel resistors deviation

I am building an audio crossover with time alignment based on Douglas Self's design. I desided to make an algorithm to calculate best resistor pair. The first part is easy: Make a list of all ...
25 views

### Is there a typical “Active Directivity” for LDMOS components?

Active Directivity is a measure of how much an amplifier's source match potentially affects its output impedance, or its load match affects its input impedance. High active directivity is a good thing....
39 views

### How do I calculate the terminal-to-terminal resistance and capacitance from an impedance matrix?

If I have a circuit with $N$ ports (and therefore $2N$ terminals), how can I calculate the terminal-to-terminal resistance and capacitance from a given impedance matrix $Z$? We can assume a ...
76 views

### Input impedance of the op-amp inverting amplifier [closed]

I have a lab exercise with inverting opamp (gain = 10, R1 = 1k, R2 = 10k). The subject of the lab is to measure input impedance of such amplifier by adding 1k resistor in series to the input and drive ...
868 views

### Definition of RLC resonance frequency

I have found that a commonly mentioned definition for the resonance frequency in an RLC circuit is defined as the condition where the capacitive and inductive reactances cancel each other, resulting ...
71 views

### How to calculate input impedance for this simple circuit?

I'd like to calculate the input impedance of the following circuit, assuming that Q1 is "active". I know that the impedance of the voltage divider is $\frac{R_1R_2}{R_1+R_2}$ and the ...
74 views

### What is an op-amp's differential input impedance?

I've heard of differential voltages, but the concept of a differential impedance is new to me. Suppose we are trying to calculate/derive the differential input impedance of the following difference ...
37 views

### Is it beneficial to use a taper for the feed input of a PCB antenna?

What is your opinion on using a taper for the feed input of a PCB antenna? Say the feed is 2mm wide and the transmission line is 0.45 mm. Would a taper just cause more impedance mismatch? Or would it ...
51 views

### Motor impedance too high at 20kHz

I have an H-bridge I am driving with an Arduino Mega. The motors I am driving are fairly large, steady state 48 watts, maximum 300 watts. I am driving them at 16 volts and a switching frequency to ...
100 views

### Why are common mode chokes with 90 ohm @ 100 MHz recommended for USB 2.0 Hi-Speed data lines?

When one looks at common mode chokes for USB 2.0 applications choke manufacturers always recommend CMC with a common mode impedance of 90 ohms @ 100 MHz. Example How does this relate to USB 2.0 ...
58 views

### How to find Z impedance if I have only S11 (db) and phase

I need to measure Z line impedance. Using VNA I measured S11 it is -53.8785 dB and phase at this point is 175.6706. Could you explain using these numbers how to find R and jR S11 = (Zx-Z0)/(Zx+z0) = -...
46 views

### Differential Impedance Matching

Below is a small portion of a schematic which I have seen It mentions that the transmission line will have a differential impedance of 100ohms between them. In case of Single ended it would be 50 ...
27 views

### How does a Touchstone (s2p) file indicate whether it should pass or block DC?

I'm trying to simulate impedance matches for an LDMOS FET amplifier with Touchstone (s2p) files to simulate the device with "real components" before we build it. I have found that "...
54 views

### Output impedance of a voltage divider with DC bias

I made a circuit simulation of a 200VAC to 0-2VDC for ADC conversion via voltage divider and DC bias with a third resistor connected to a 3.3V supply. What is the output impedance of the divider and ...
37 views

### The transient instantaneous power dissipation of an impedance

Suppose we have a resistor of value R in parallel with an inductor of value L with series resistance R. The impedance of the network is $$Z= R\frac{sL+R}{sL+2R}.$$ simulate this circuit – ...
63 views

### Speaker Line Supervision

I want to design a circuit for 100V loudspeaker line control. I want to periodically check if the line is short circuit or open circuit and receive notifications in case of any short/open circuit. I'...
67 views

### In practice, does the order of a series RLC-shunt circuit matter?

In simulation I'm finding that the image pictured below works well to optimize a complex impedance match. I know that Z = ZL + ZC + R, so in theory the order shouldn't matter---but in practice, with ...
98 views

### Why the capacitive divider in this output stage?

I have this output driving stage, reverse engineered from a generic Chinese mist generator: The goal is to drive the piezo transducer with a given frequency (more or less 1.7MHz or 2.4MHz depending ...
39 views

### How to calculate $Z_1, Z_2$ and $Z_3$ in two-port circuit?

I should calculate $Z_1, Z_2$ and $Z_2$, where $a_{11} = 1.8, a_{12} = 2kΩ, a_{21} = 1*10^{-3}S$ and $a_{22} = 5/3$? Also, all impedances are resistive, i.e. resistors. I have no idea how to ...
43 views

### Complex impedance calculation for resistors and coil

I have this circuit and I need to calculate the total complex impedance. Note: the $r$ is internal resistance of the coil so how can we calculate the complex impedance? The coil and the resistance \...
262 views

### How should I probe when measuring output impedance? Why do I get inconsistent readings?

I am trying to measure the output impedance of a commercial headphone amplifier, but the results seem to change depending on how I probe it. When I plug a 1m cable into the device and the other end ...
49 views

### Calculate impedance in time and frequency?

I'm characterizing the impedance of a system. To get the impedance I apply a sum of sinusoidal voltage waves that basically looks like noise. I recorded the output current from the system. As you can ...
72 views

### What is the relationship between the RPM, power, and impedance of an induction motor?

Does an induction motor draw more power at higher RPM? Increasing the frequency of the AC power supply will increase the RPM of the induction motor. However, that should also increase its impedance (...
53 views

### Impedance matching of an amplifier circuit with a filter at the input and output

I created an amplifier circuit with a filter on the output. I did impedance matching on the input and then did matching on the output as well. From the graphs below, is the circuit more matched? ...
83 views

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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 ...
74 views

### 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 ...