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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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Differential amplifier, superposition theorem, output derivation, what is a loop here?

So based on this article, when V_1 is grounded, in this picture: Is the loop number 1 correct? Or does R_3 and R_4 both belong to the same loop?
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Is it possible to very roughly estimate the CMRR degredation of a differential amplifier due to source imbalance given its datasheet

In the datasheets of differential input amplifiers there is a figure of merit called CMRR. This is normally experimentally measured at a particular frequency like 60Hz and presented in the datasheet ...
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50 views

To Fail-Safe or not Fail-Safe on RS485/422 Transceiver

I'm stuck on a PCB design issue. I'm designing a new PCB (Daughter board) that will plug (via DB15-F to DB15-M) onto another PCB (existing Mother board) and the design intent is to take (from the ...
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49 views

PCB controlled impedance

Hi) I want to calculate the width of my 100Mb Fast Ethernet MDI diff pairs. I've got some software (TXLINE 2003 Microstrip). I have 4 layers. The second layer is GND, the third is power, top and ...
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Comparing differential-ended and isolation amplifier outputs for an “unbalanced” source input

I tried to simulate the effect of common-mode interference on unbalanced sources for three different inputs: single-ended, differential-ended and isolated. Below I inject a 1V common-mode voltage to ...
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54 views

How to conclude the necessity for unbalanced to balanced signal conversion for this scenario?

This is a bit specific system related question about simultaneous data-acquisition for several transducers. Therefore hope you don’t mind for the long intro and the question. It would be too implicit ...
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62 views

Contradicting ideas about differential signal route, confining fields vs Increasing impedance

By initial sense I think we must: keep pair intra-distance as close as possible for field cancellation. Fill surround of pair with GND plane and have via near to it to confine the fields, prevent ...
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59 views

Why Im getting shifted phase in the output voltage?

Why im getting shifted phase in the output voltage in this differential amplifier? and how can I eliminate this shifted phase? Second question is, I need to make a gain of 50 in the amplifier below, ...
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79 views

Which load resistance is connected to generator U2?

I have this op amp and one of the questions says Which load resistance is connected to generator U2? This is my attempt but I can not confirm if it right. No it's not homework, it examples I'm ...
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53 views

RS485 termination

What is the recommended way for termination RS485? I read about couple of options to do this. If I don't want to do dissipate extra power, can I just put 120 Ohm resistor? I saw the follow ...
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42 views

Differential Pair Reference Plane Coupling

I am routing LVDS pair on a flex board. The signal is 264MHz. I used Saturn PCB design to calculate width and spacing between conductors. The targeted impedance for diff pair is 100 ohms, which is ...
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62 views

Why don't I get a signal on the load?

I don't get any signal on the load, what am I missing? Shouldn't it amplify the input signal? I have 50mA from the current mirror, the Vbe on Q10 and Q11 is around 0.75v
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Trying to view CM and DM components of a signal on a two channel digital scope screen

I want learn how to view the CM and DM components of a signal on a usual two channel scope. The reason for this to be able to verify whether a noise superimposed on a signal is CM orDM. Regarding my ...
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Differential Amplifier Exam Problem

I am lost with how to approach part C and D of the question. In fact, I need some intuition with how to tune a differential amplifier.
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61 views

When does differential signalling become necessary [closed]

Is there an industry rule of thumb or application note etc for when differential signalling becomes necessary for reliable communication? I'm thinking mainly in terms of distance and signal speed (...
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43 views

LVDS driver signals measurement

This is background: I have a self-made PCB, which is used to connect the camera via the CameraLink interface. When I connected everything together, it turns out that the camera is signalling me via ...
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46 views

Differential equation for current driven RC circuit

I need the differential equation for the following circuit for numerical integration purpose. It is driven by a time dependent current source. So the question is: How can I know \$U(t+dt)\$ given \$...
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Ethernet diff pairs

We want to design PCB with an oppotunity to build the board for copper and fiber both (depending on the customer needs). For media convertion we use DP83849IF IC (This IC converts 100BASE-TX to ...
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80 views

Adding multiple differential signal

As I asked in "Adding multiple analog signal" before, I got that: for adding some signal together, we can only use op-amp, instead of lovely integrated circuit (ough). But the question arise because ...
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57 views

Mathematical model for differential signals and relation with reality

i have a question and i hope is not that strange. i spend some time asking myself how people came out with the mathematical model for differential signals and why is this better in this way?! to be ...
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138 views

Differential Opamp Strange Behavior

I have no answer for this strange opamp behavior. The circuit shown is from a typical nonisolated ,Non grid-tie inverter product (imagine H bridge Inverter). which has a common -ve high power circuit ...
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Differential to single ended - Design bluetooth for car stereo

I'm trying to install bluetooth to my car through cassette tape deck(aux already installed). So I find board with CSR8675 which supports APTX-HD https://www.aliexpress.com/item/-/32817838770.html ...
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48 views

LIN to RS485 and back to LIN

I am currently communicating between two microcontrollers using a single pin and the LIN protocol over a short distance of 0.2m. Now I would like to extend the distance up to 5m by differentially ...
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Differential Clocking resistor and capacitor choices

I am working on generating a 2MHz differential clock signal for a DDS chip. I have been given a PCB with a design that I am unsure can work or what the thought was behind it. If anyone could help with ...
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32 views

Terminating Unidirectional Differential Signal

In a project I'm working on, I'm planning to use the SN75174 to send a signal through about 30m of twisted pair. This signal has a bitrate of around 1Mbps (it's a signal to drive WS2811 LEDs,) and ...
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82 views

Does LVDS always need 100 ohm differential impedance?

LVDS pairs need 100 ohms differential impedance. However, I am having trouble achieving that in my design. My design requires that the pairs travel over very thin flexible PCB, about 50mm total ...
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74 views

RS485 Waveform while Receiving Data

I was testing the RS485 Circuit, below is my circuit and I connect J5 to my PC using another RS485 to USB converter. In PC through Modscan software I was monitoring the polling and response, a twisted ...
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93 views

Virtual Short Concept in an Op-Amp

By virtue of the open-loop gain being infinity for an ideal op-amp, the two input terminals are said to be virtually shorted. Yet, the virtual short concept is only applied to op-amps in negative ...
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1answer
84 views

How to measure a 100 ohm differential signal on a spectrum analyzer?

I have a pair of 1.5V PCML differential signals coming out of an Altera Cyclone V GX FPGA, terminated on the FPGA in 100 ohms with common mode voltage = 0.65V (also provided on the chip). I need to ...
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47 views

Differential signal isolation

In differential signal circuits (specifically, RS-485), there is usually an isolation between the signal processing / generation stage (eg, microprocessor) and the line driver chip (something like a ...
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3answers
109 views

Differential to single ended audio signal

I'm working on an interface that will be connected instead of a speaker, input of my interface is differential, and output is single ended. I'm using the following schematics : R3 is the load to ...
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1answer
28 views

I need to find Vin max(Common Mode) and min(common mode) for given circuit.

please let me know how i can proceed with this circuit
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22 views

Via size on PCB to maintain impedance for differential signals? [duplicate]

I have a question regarding impedance control and vias. What should the via size be to maintain the 100 Ohm impedance for differential signals on a pcb?
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1answer
55 views

Why does LVDS (or any differential signaling for that matter) use a common mode voltage of 1.2V instead of 0V?

Why does LVDS (or any differential signaling for that matter) use a common mode voltage of 1.2V instead of 0V? Is there an easy way to shift the common mode voltage to 0V?
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53 views

What is a good way to add a programable offset to a diffential signal?

I have an AC coupled, ~10 MHz to 1 GHz, differential signal, with a programmable gain, coming from a detector. The signal contain pulses, and the DC-balance is poor but constant (even if my hand ...
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Does Differential Amplifier Emitter behave as ground in AC-analysis?

I am trying to solve various differential-amplifier homework problems for which I have the solution to study. For the simplicity of most problems we are able to neglect base-currents. Moreover, it ...
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89 views

Microstrip and CPWG transitions on PCB

I've been doing some simple RF boards as part of an internship in a lab, mainly to test particular ICs and prototyping, and mainly using coplanar waveguides. I've now been tasked with designing a ...
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99 views

How do you model differential inductor in LTspice?

I wonder how I can model a differential inductor in LTspice? I've an inductor that has half the turns on one side and the other half on the other side. It's intended to be used in a bridge tied ...
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71 views

Need to convert unbalanced to differential input OPAMP

I have the following filter after the DAC chip (currently with unbalanced outputs) working very well, but I need now to change the DAC chip. The new source has differential outputs. Is there a ...
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1answer
42 views

LAN9512 differential wire routing on PCB

Using the Saturn PCB Tool (V7.05 - calculation method IPC-2152 - Etch Factor 1:1), in order to achieve a 90 ohm differential line with a single line impedance equal to 50 ohm for a design based on the ...
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69 views

OTA design, the Gm won't go down to zero

I'm trying to simulate a pseudo-differential OTA, but the the Gm vs Vin(differential) plot I obtain seems warped. The Gm won't go down to zero for large values of Vin. attached is the circuit ...
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75 views

GPS L5C Differential? Max Update Rate(bits/s|Hz)?

The differential GPS chips use L1 and L2C to calculate the ionospheric interference. With the new GPS satellites, the new band L5C is being deployed, and I am wondering about the following things: ...
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59 views

Differential amplifier and large signal analysis

Let's consider this circuit: Razavi makes the large signal analysis in the ideal case, that is with an ideal current generator. He shows that Ic1, Ic2, Vout1, Vout2 and (Vout1 - Vout2) are function ...
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79 views

Differential amplifier and differential signals in small signal analyses

I'm studying the differential amplifier on different books (Razavi and Sedra-Smith). I've understood how this circuit works, but I have some questions. When authors analyze this circuit (2 identical ...
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94 views

Differential amplifier circuit - output voltage

I have a homework problem. We have a differential amplifier circuit with two supply sources: \$V_{CC}=-V_{EE}=5V\$, that has two identical NPN transistors and three identical resistors. T2's base ...
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153 views

SPI with differential signaling

Standard SPI uses single-ended signals. Is it possible that a communication uses SPI protocol but the signals are physically LVDS?
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92 views

Input filter on differential amplifier input

Hi, I need to determine the transfer function Vout/Vin. A traditional differential amplifier transfer function without the 2.2uF on the input side would be G1 = (Z2/Z1)*Vin, where Z2 = (2.2uF // ...
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241 views

Single ended to differential conversion with voltage divider

Let's assume I have an AD-converter that expects a differential signal with zero common mode voltage and I want to connect a single ended signal source. If the AD has it's own isolated ground, couldn'...
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161 views

Differential amplifier circuit, problem with saturation

I have a homework problem regarding differential amplifier. We have a differential amplifier with symmetric supply (i.e. \$V_{CC}=-V_{EE}\$). Emitters are connected to a perfect current source \...
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46 views

Differential Amplifier constant output voltage

SE-Members, The past few days i've been figuring out why my circuit does not work. It is a simple differential amplifier with a gain of 2. The OpAmp is the "TLE2027CDR". My problem: The output voltage ...