Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [differential]

Differential refers to any kind of signaling where the signal information is carried by two or more paths and both are required to properly reconstruct the signal. For example, USB D+ and D-

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Review request: DIY DC to 50MHz differential oscilloscope probe

Given the cost of proper differential probes, i've decided to make my own. The requirements are: DC to 50 MHz 3db bandwidth A few selectable input voltage ranges, from 3V pk-pk to 300 V pk-pk Better than 1/500 common mode rejection ratio A…
jms
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Difference between differential op amp and comparator

What is the difference between a differential op amp and a comparator? I know a comparator can only give me two values (the supply values). The differential op amp amplifies the difference between the inputs...but should a comparator not do the same…
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How critical is the layout of USB data lines / how does my layout look?

I'm laying out the USB data lines on my board at the moment, and I'm just trying to get an idea of how well off my design is gonna fare. Here are the particulars: 4 layer board (from the top: signal, ground, split power planes, signal) internal…
Toby Lawrence
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USB signal routing - Swap data lines using vias?

I'm making my second USB design, but the D+/D- pins on the MCU (atemga16u2) aren't in the right order for the micro B connector. What's the best practice for routing these to go the right way? My current idea is to rotate the atmega 180 degrees and…
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Difference between natural response and forced response?

Reference Second post on EdaBoard.com Time response of a system is the time evolution of the variables. In circuits, this would be the waveforms of voltage and current versus time. Natural response is the system's response to initial conditions…
bluejamesbond
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How do I measure differential signals (like RS-485 or DMX) on an oscilloscope?

I've encountered differential signals in a few places, such as a differential output audio amplifier and now in a project working with DMX which is similar to RS-485. (Here's a similar question about RS-485.) Looking at a waveform from a DMX…
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How can I improve this Ethernet differential pair?

This is my first 100 Mbit/s Ethernet project (I am doing it to learn more about differential signals). I did two things that I don't know if are good or bad in this particular case. One is to route under the signal transformer. It is only slightly…
Javier Loureiro
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USB differential pair length

I am routing a PCB that uses a USB connection. The differential pair traces are 10 mil distant from each other, and they are about 1mm different in length. Is it going to be a problem? What is the recommended maximum difference in length and the…
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Differential Signals - Why is having an equal impedance an advantage?

I lately heard in a course that a main advantage of differential signals is that both signals show the same impedance, whereas a single-ended signal, which is measured against ground, has a high impedance at the point of measurement and a low…
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How do I lay out PCB traces for a given "differential impedance"

This is an attempt to craft a good general question and answer for a topic that's been asked before, but only in specific situations. Could you describe what I need to know, prior to laying out a PCB board for a differential signal pair with a…
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Can I use differential I/O pins of FPGA as high speed comparator?

High speed comparators are rather expensive and speed is what FPGAs are very good at. On the other hand, FPGAs (in my case: XC3S400) have paired differential pins in each bank that their voltages are compared ( At least I think so !). They also…
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Trace impedance ohm meaning

I've been trying to understand the principle of trace impedance (single ended and differential) for a while, read several articles (all the best google has to offer), but I have still some serious issues finalizing my understanding of it. First of…
Ilya
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Do USB Data Wires (D+/D-) have 90 ohm differential impedance and single ended 45 ohm impedance to ground and if so how is this made?

I understand that USB data transmission is done over various speeds where transmission line effects could come into play(max 480Mbps which means a max frequency that is much higher considering the square wave harmonics/edge rate, perhaps 5th…
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Generating a differential signal

I was given a small task (actually it's part of a much larger task) where the requirement is to generate a signal which looks like it came from a microphone. The following requirements needs to be kept: 1.0Vpp Sine Wave Differential Now these are…
Tom L.
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Ground connection in differential signals

Do I need a ground connection when connecting differential signals between two systems? I was thinking this should not be needed, but how will common mode voltage at the receiving end behaves? Without connected the ground between the two systems, I…
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