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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Is the impedance control of differential pair traces a transmission line problem?

I read in an article of design reference that "If the length of the interconnect PCB is greater than 1/10 th of the wavelength, we should consider using the transmission line instead of ordinary ...
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107 views

Detect if a CAN node is transmitting or receiving

I am not an electrical engineer or EE student; I'm a diagnostic technician. AFAIK, a CAN transceiver receives bits by measuring voltage between the network and its ground/low reference (high ...
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58 views

differential amplifier gain

i know that the differential gain of the differential amplifier ( mosfet or bjt ) is _gmRc or _gm Rd looking at the curve : if the current went down in one side and up in one side the gm will change ...
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20 views

How can i get the Q operating point of the differential amplifier?

I'm working with this type of configuration: Differential amplifier, and I need to find the current for this circuit so I can have maximum symetrical swing, and for that, I need to find the operating ...
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163 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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35 views

Designing a two stage differential amplifier with MOSFETS

As a part of a "Test you understanding quiz" i had yesterday at school were we tested our understanding of differential amplifiers and mosfets i came across a question that asked us to design a ...
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127 views

Use of virtual ground to split ground loops?

So I have a "broadband" signal (DC-5MHz) which I'd like to send over coax cable to two other circuits referenced to the same ground. Simply floating the other two circuits is not an option for ...
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51 views

Transitioning between 90 and 100 ohm diff pairs using coupling caps?

I'm building a PCB carrier for an FPGA SoM. The SoM has 100 ohm diff pairs routed for all the high speed IO. I'm implementing USB 3 on the carrier so should be routing 90 ohm diff pairs. What is the ...
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50 views

input resistance of differential amplifier

i have a question about the differential amplifier i know that the input resistance for the common mode is Rin = rpi + 2 Beta Ree / 2 but my question is what is the input resistance for the ...
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103 views

Question about differential amplifier

why is there 0.7V instead of 1.2V on the common emitter? if you go through Q1 mesh : Ve = 0.5+Vbe = 1.2 instead of Ve = 0+Vbe = 0.7 from Q2.
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195 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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49 views

Differentiator circuit sees noise on PCB after 2 min

I'm new to PCB design, and looking for some advice. I designed a PCB shield and I'm seeing a lot of noise in my differentiator circuit. The circuit will run perfectly for about 2 min and then all of ...
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Differential amplifier CMMR, NON-IDEAL Op-Amp used

I have a little trouble with the analysis of a differential amplifier. What I want to do is to determine the CMRR of the whole amplifier taking into consideration the CMRR of the op amp. This is the ...
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52 views

Oscillations on High Side Sensing Current Source

I designed a simple adjustable constant current source that uses high side sensing but I can't seem to figure out where the oscillations on my output are coming from. The circuit is shown in a picture ...
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54 views

Should Ethernet MDI Pairs all be Length Matched (Inter-Pair) before going into magnetics?

I've been trying to find information for the above question and I can't seem to find anything. I have 1000 BASE-T lines coming from an Ethernet cable to a PCB mounted connector. I'm pretty much ...
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34 views

Singled ended or Differential - Engine Control Unit

I know this topic has been beaten to death but I still have not got a clear understanding. Pardon me for my bad explanation as I am an automotive engineer by trade. I am simulating an engine knock ...
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38 views

How critical is it for SN65HVD1780DR A/B Differential signal lines to have matched trace length?

How critical is it for the A/B differential signal lines of SN65HVD1780DR to have matched trace lengths on PCB?
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29 views

Current source for discrete differential amplifier

I hope someone can point me to the right direction. Basically I face the same problem like the author of the following question. How do I choose the correct current for my differential amplifier? I ...
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39 views

Common Mode Noise on Differential Lines Driven Against Chassis GND

How is common mode noise filtered on differential lines that have a noise source that is driving them relative to chassis GND? I drew a picture of what I am imagining below. Imagine a PCB with ...
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59 views

Does it matter if differential pairs have no reference plane or cross reference planes?

More specifically, does it matter on a PCB if routing differential pairs if they cross reference planes? Do they need a reference plane? Is there even a reference plane with a differential pair? I ...
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156 views

What is sense terminal/pin in differential amplifiers?

I sometimes encounter a connection terminal called AISENSE in some data acquisition boards. I also see a pin called SENSE in diff. and Instrumentation amplifiers. An example(look at the pin called ...
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110 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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340 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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176 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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74 views

How to analysis this Operational-Amplifier circuit?

This is a reference buffer circuit that make a single-end audio input to be the differential inputs for ADC. Circuit-1: It does not like typical Op-Amp circuit of the same purpose like below. ...
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37 views

Increasing drain current, decreases common-mode level

The basic idea behind the CMFB setup is that increased output common-mode level feeds back into the gate-source of the triode devices and causes drain current to increase and hence output CM level to ...
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189 views

Differential Amplifier with Hard Limiting

I'm currently going through RF Microelectronics by Razavi. In chapter 3 he presents an example where the following signal is applied to a differential amplifier with a tail current source. $$Acos(...
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90 views

Some issues modeling a “two terminal source” coupled to a differential amplifier in LTspice

Below is a circuit where on the left there is a floating single-ended source which directly couples as an input to a DC differential amplifier: So the idea is to be able to simulate a real scenario ...
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8k views

How to use common mode choke inductors? (differential vs common mode)

I have yet to undestrand exactly how to use common mode chokes inductors, according to the datasheet they have 2 operation modes like in the picture common mode and differential mode, however im ...
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858 views

Differential ADC and Common Mode Voltage

I am trying to understand a little bit more about common mode voltage. I am working with a particular MCU, the TMS320F28377S, and it has a common mode voltage requirement for its positive and negative ...
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149 views

Is there a need for reference plane for differential traces

Is there a need for a reference plane for differential traces. I have seen cases wherein people use unshielded FFC cable like ones from Wurth Electronik for a board to board connection of differential ...
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33 views

Impedance matching of USB device WITHOUT cable

If I understood correctly, when designing PCB with USB, the 90-ohm differential pair of D+/D- trace if for matching the USB cable differential impedance. Otherwise, there will be a signal reflection ...
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50 views

Gilbert Cell Output Current

I do not understand the basic of a Gilbert cell. I see that as its output we consider the output differential current Io. But I do not understand it. Is the load connected between the points 1 an 2? ...
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40 views

How to find the Common Mode Rejection Ratio of this circuit?

My attempt was like, by using the formula, I can get, \$CMMR=\frac{\sqrt{2\cdot4\cdot8\cdot5\cdot10^{-6}}\cdot44000\cdot2}{x}\$ For the denominator, I used both 10% and 20%, but all the finals were ...
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480 views

DDR4 differential pair routing guideline

I have a question about the DDR4 trace routing on the server main board. For clock and DQS signals, are they both considered differential signals? I checked the Intel PDG; it shows that two specs ...
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410 views

Transient analysis with differential equation

Anyone may help with the differential equation for vC? I write the Nodal analysis equations and find equation for vC but roots of characteristic equation is incorrect! v1 – the node where current ...
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48 views

differential measurement vs ground

I am looking to measure an incoming V vs ground with an ADC (MCP3424 or equal). The Vin vs Gnd can be anywhere from -1.5V to +2.0VDC. I looked at using an op amp with level shift, when I came across ...
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3k views

How is a common mode signal generated in a differential amplifier?

I searched for information about common mode signals but I only got a vague idea about it, such as it is a noise signal generated between input signal and common ground. However, I do not understand ...
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65 views

Differential pairs; length matching between pairs

I'm currently busy routing a high speed design containing MIPI signals @ 2,5Gbit / lane to a connector on an 8 layer board. As MIPI also contains a clock pair, it is advisable to match the length ...
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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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62 views

How to write inductor ODE equation properly?

I've drawn a following scheme, and now want to write ODE system for describing inner processes, in order to explore it: simulate this circuit – Schematic created using CircuitLab I wrote the ...
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140 views

Using a fully differential amplifier as a differential ADC driver

Regarding my previous question, I decided to use a “fully differential amplifier” to obtain a voltage gain of 10. The source and ADC are also differential. The source is unipolar and its output ...
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257 views

Voltage output waveform of a differentiating amplifier

I have the following picture of the input and output voltage waveforms from a differentiating amplifier as shown below: And the schematic is as shown below: My teacher claimed that these waveforms ...
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86 views

differential grounded coplanar waveguide, GND-sig-sig-AVDD instead of GND-sig-sig-GND

I know we can route microstrips on top of both ground and power planes, but can we use Grounded coplanar in this arrangement? bottom is GND In top layer we have one GND and a PWR. All gaps are 0.15mm ...
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546 views

Remove DC offset from differential output, rotary encoder

Op-amp in my circuit is accepting differential sinusoidal signal, that swings around 0 V with 1 Vpp. It is configured as a comparator - swings to upper rail when the signal is positive and swing to ...
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94 views

Bipolar signal used in differential ADC

I'm trying to find a way to convert a bipolar signal from a load cell (Futek) to an input for a differential ADC on a TIVA microcontroller(TI TM4C123GH6PM). The load cell's amplifier outputs a bipolar ...
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44 views

Bonding DC Minus to Ground with Resistor for Remote Power?

Layout: I have a system that has 3 serial networks that run a variable length with one central processor talking to multiple endpoints via Modbus RTU, Canbus, and another rs485 that talks a protocol ...
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3answers
5k views

differential trace impedance for USB (90 Ohms) on 2-layer FR4 board

I am currently working on the USB hub part for a multiport USB-RS232-converter. The current design is for Terminus Tech's FE 2.1 Hub IC. Regarding the impedance of USB signal traces the layout ...
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48 views

Is difference amplifier a differential amplifier with a voltage gain of one?

I see these two terms are used in same context. But what is the difference in meaning? Is difference amplifier a subset of differential ampfier with unity gain? I couldnt find a duplicate question.
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Calculating current and voltage from RL circuit through differential equation

Our circuit, where R1 = 3 Ohms, R2 = 1 Ohm, R3 = 2 Ohms, L = 5 milliHenry, and I = 0.01 Ampere. Trying to figure out the differential equation for this circuit, as well as the current for the ...