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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How can I allow a smaller clearance value for differential pairs in Altium?

I have finished routing a PCB in Altium (v17) and am resolving design rules violations. In short, everything checks out except differential pairs that are violating the ...
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2answers
146 views

Capacitor Voltage during Transients

I am starting to learn transient analysis series RC which requires our own equations to be derived, but I don't understand how the voltage across the capacitor is given in the equation below from a ...
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91 views

Does polarity of differential DisplayPort signals matter

I am routing a DisplayPort interface. I know from PCIe that the polarity of the differential pairs does not matter. So if it is helpful during routing I can connect the n to the p pin and vice-versa. ...
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1answer
87 views

How to measure the coil voltage in this circuit? [closed]

I want to measure the coil voltage (coil+ to coil-) of the following circuit with my microcontroller, but I don't know how. Do you have some hints or suggestions for me? Thanks!
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63 views

Differential bandpass filter Audio application

I am developing an Audio project which is required to output a signal between 10kHz - 40kHz at ±1V. The sound is produced from an AD9106 chip which is interfaced to the following circuit: When ...
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58 views

Buffered Voltage Divider VS Differential(Subtractor) Opamp

I'm trying to understand which one of these circuits is the best choice for measuring 400VDC signal using a microcontroller . But at first look circuit number 1 makes more sense since it is giving the ...
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2answers
68 views

Does this audio amplifier do differential filtering?

I was looking at this schematic for a two-channel audio power amplifier. The amp supports a bridged mode by means of an XLR connector and a switch. When the switch is in the XLR position, pin 2 (...
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43 views

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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65 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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1answer
63 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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46 views

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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71 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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94 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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63 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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1answer
91 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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2answers
81 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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1answer
215 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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66 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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42 views

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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54 views

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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1answer
66 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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114 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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2answers
57 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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1answer
106 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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63 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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175 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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2answers
105 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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49 views

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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44 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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1answer
278 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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1answer
158 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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2answers
527 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
177 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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82 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
174 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
45 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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1answer
85 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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1answer
58 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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2answers
109 views

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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1answer
190 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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1answer
191 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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1answer
100 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
50 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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1answer
88 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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1answer
98 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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1answer
146 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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2answers
134 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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102 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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1answer
330 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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159 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 // ...