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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1answer
69 views

How does a twisted pair cable reduce inductive coupling compared to non twisted pair cable?

Can anyone explain this concept with figures for both non twisted pair cable and twisted pair cable?
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38 views

how to find voltage difference between two points(Ethernet) by using two single-ended on oscilloscope

I have an MDO 4000(Tektronix) and two TPP1000 probs, I am trying to do a trigger on an Ethernet cable. I connected the first prop on the color (orange/white-orange) and the other on the color (blue/...
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In a differential pair BJT amplifier, the individual gain of the transistors should be equal. Why am I getting different gain for each transistor?

Here I have taken a differential BJT pair. Both the individual gains are different and the output differential gain is also different. Is there a problem with my circuit? Why is it happening?
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61 views

What kind of amplifier do I need for differential to single-ended audio conversion?

This is a follow up to my previous question: For my Amazon Echo related project, I realized that the speakers in the Echo are being driven from a differential amplifier, and not a single ended one. ...
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1answer
45 views

Differential Pair Routing PCB

First at all, thank you so much for all the answers I have received on all the threads. Well, I'm working on PCB Raspberry Compute Module 4 Carrier including USB 3.0 Controller (TUSB7320) using PCIE ...
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288 views

Differential probe input impedance 1Meg, but 50ohm oscilloscope mode recommended

I will be experimenting with the Keysight company's N2792A differential probe. Looking at the datasheet of the probe, the input impedance is 1Meg, but it is said to be used with the 50ohm impedance ...
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1answer
45 views

Laplace transform rotational mechanical system

I have a system with an input torque Te and output angular velocities w1 and w2. I have defined the outputs relative to the system however cannot seem to work out how to find GM(s). omega2 is the ...
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24 views

Why does the output of the mosfet differential pair connect to the gate of the pmos of a common source amplifier?

I'm told that a simple operational amplifier made from MOSFETs can be shown in the picture below. M1 M2 M6 and M7 make a differential amplifier. M3 is used as the reference mosfet to create a current ...
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CW Doppler probe for fetal doppler and blood flow velocity

I am currently working on a microcontroller based project to measure the blood flow velocity using ultrasound doppler. I have purchased two Spengler 8 MHz continuous mode probes in order to measure ...
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1answer
38 views

How do cheap Raspberry CSI-2 cables get around differential impedance matching

I am trying to design a circuit on (double sided) flex PCB that happens to have CSI-2 signals on it. I would like to find out what is wrong with my deductions presented below, or what part of ...
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3answers
58 views

LVDS/differential driver source impedance matching

A very basic/stupid question.. I'm designing some LVDS multipoint pcbs, and I'm a bit confused about the source termination on the driver end. my colleague said that ideally there should be a 100ohm ...
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1answer
61 views

Why is input resistance parallel with the base of BJT?

I'm solving for the third stage. The resistance looking into the base of Q7 is taken between its base terminal and ground as follows during small signal analysis for single end gain of Second Stage ...
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1answer
75 views

Can USB 3.0 tracks be closer together than 5W if they're quite short?

I am currently laying out a space constrained PCB which contains some USB 3.0 Superspeed differential pairs. These USB signals are confined to the PCB, going from a Cypress CX3 chip to a USB 3.0 Hub ...
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606 views

Amplify difference between two photodiodes

I have two adjacent photodiodes in photovoltaic mode, with two transimpedance amplifiers. Unfortunately, my MCU (nRF52840) is one meter away, and I expect a fair amount of noise to enter the system. ...
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1answer
24 views

MCP2551 sending with 4V differential voltage

I'm working on a CAN Bus Module with ATMEGA328P, MCP2515 and MCP2551. In my test setup, I have the module connected to a Raspberry Pi with a CAN hat. The communication works in general - both nodes ...
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USB differential data lines pulled up to 5 V

My design uses the compute module 3+ board from the raspberry pi foundation. I used the FSUSB42MUX schematic from the CMIO board to have a slave/host USB port. My problem is the D+ and D- lines are ...
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Is there software with CAS to solve drawn electrical circuit in form of differential equations which describes that electrical circuit?

Is there any software with Computer Algebra System to solve drawn electrical circuit in the form of differential equations which describe that electrical circuit? Or to write symbolic solution (...
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Differential pair length matching considering phase

According to Microchip's document Implementation Guidelines for Microchip’s USB 2.0 and USB 3.1 Gen 1 and Gen 2 Hub and Hub-Combo Devices, the Superspeed differential pairs should be length matched ...
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2answers
86 views

Op amp differential amplifier output level too high

I'm trying to implement a current limiter for a buck converter charging a 2.7 V super capacitor. The design uses an op amp differential circuit that then feeds a comparator: I have simulated the ...
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23 views

Inaccurate differential voltage measurement

I tested 3-level PFC voltage initialization event in practice using 1 x single ended probe to measure the output voltage as well as 3 x differential probes to measure the precharge voltage levels of ...
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2answers
87 views

creating a differential amplifier for low voltages (current shunt)

I'm trying to create a "precision" fully differential amplification stage, to measure uA on a 10R shunt, and mA on a 0.01R shunt. shunt resistance values are set at those values for burden ...
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1answer
59 views

How to make sense of the math behind differential opamp

My first question here! So, I'm designing a simple fully differential amplifier. The final target will be to implement a low pass filter (but I'm not there yet). Although all seems perfectly fine in ...
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1answer
54 views

Understanding specifications

I have a differential signal which I want to measure with a differential probe. While reading the specification of the probe, I got confused with a few terms. Can someone what the highlighted terms ...
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48 views

What are these on the probes

I am having a Lecroy differential probe and trying to measure a LVDS signal. This is the Reference Manual which I am referring to as a guide. My differential probe tip/lead model number : DX20 - SP/SI/...
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2answers
70 views

What kind of PLL is used to recover the clock from E.G. USB 2.0 data stream

I would like to create a communication protocol to connect two FPGAs. I would like it to be fairly fast, (a couple of 100s of Mbps) but only use a single differential pair. This kind of thing is ...
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3answers
65 views

Using a power plane as signal reference

I am going to route Ethernet differential par in a four layer PCB which contains Top, PWR planes, GND plane and Bottom stackup. These diff pair are going to be routed in the top layer. In order to ...
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Design Problem in differential Amp

It's my first attempt to design CMOS Differential amplifier in 0.35um technology using a cadence tool. I will explain my approach in deriving dimensions of MOSFET's used in it. Moreover, I have also ...
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1answer
73 views

Difference in signal speed for a high speed signal when it is driven as single ended and differential?

This is a thought experiment. I would like know and what will be the bit-rate in differential channel when signal is driven differentially and in single ended mode? Lets there is differential trace ...
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27 views

Differential Signal Measurement best practice

I have 4 differential signal pairs (LVDS Data lines and Clock) running between my Microcontroller and TFT. There are no test points over the lines. Can someone tell me what is the best practice and ...
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1answer
24 views

LvPECL TX and LVDS RX

I have a quick sanity check question because it seems too good to be true. If I have a LvPECL signal that I want to receive, I can just use a LVDS receiver (422/485 specifically) right? From reading ...
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636 views

Why do differential signals need an inverse wave?

At the moment, I'm working on converting a single ended audio signal to a differential one (source is a CS42L55, need a differential input for a CSR8670. The latter's datasheet is indecisive about how ...
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44 views

What's the difference between these two differential mode EMI filters?

When I search for differential mode input EMI filters (for power supplies), I get two different filter types: simulate this circuit – Schematic created using CircuitLab What's the difference ...
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1answer
43 views

Why this LVDS transceiver doesn't specify the differential input polarity?

I've been looking to implement a LVDS transceiver in my project where i can hook up to Displayport AUX differential pair. I've discovered a suitable part, SN65MLVD200A in the following design ...
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1answer
46 views

Reading differential signals

By the circuit shown bellow I wanna read the ripple current by the 0.33 resistor and the ripple voltage of the capacitor by adding a low pass filter to reduce the spikes and a high pass filter to ...
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3answers
145 views

Confusion about differential amplifier configuration

As in the picture shows the signal applied at the base is say 1mv p-p, the circuit bias is not provided, then how this 1mv p-p able to forward bias the B-E junction?
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1answer
19 views

surface/external edge coupled microstrip vs (internal) asymmetric edge coupled microstrip

In the process of determining the track width/separation of differential pairs for a board design that needs to route usb2, pcie(90R) , gigabit ethernet(100R), CSI/DSI(100R), HDMI im looking a a four ...
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2answers
72 views

negative voltage of a differential amplifier

Can somebody explain what is this negative voltage -VEE in the circuit? I thought two parallel circuits are connected to the power supply vcc, but how this VEE came? Can somebody explain me this using ...
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2answers
340 views

Differential pair biasing by current sources

I'm having a problem understanding of how can a current be injected into emitter and pulled into collector via base, using only current sources at emitters and collectors of differential pair and not ...
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1answer
31 views

Shorter transmission lines or nearer high frequency bypass caps

I have an application where I have a sensor which communicates with an FPGA with about 15 differential pairs of data clocking around 300 Mhz. Due to constraints, the board can't be taller than 35mm ...
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0answers
56 views

Load curve control via differential pair

Last few weeks I have been designing a circuit, which is inputted with saw wave and outputs (amplification fairly linearly if possible) amplified voltage across two loads, where load voltage/current ...
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2answers
105 views

Is it possible to make a high-impedance voltage follower using a fully-differential op amp?

With a single-ended op amp, I can create a unity-gain voltage buffer like this: simulate this circuit – Schematic created using CircuitLab The input impedance of this circuit is equal to the ...
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1answer
55 views

Routing Differential Lines vs PCB Fabrication Constraints

I'm in front of a big question. I need to route 90 Ohms differential lines for a USB 2.0 Project. I understand how to use tools like Saturn PCB Design to give me the correct spacing and lines width. ...
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0answers
19 views

Operation explanation of a low-swing differential receiver (amplifier)

The following figure shows an example of a low-swing differential receiver given in Hall's Advanced Signal Integrity for High Speed Digital Designs However, I cannot figure out how this circuit works ...
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35 views

How to identify a coax connector vs twisted pair connector

I need to have a connector that will bring in COAX input to my PCB. I have this Rosenberger HSD Connector Catalog. On page 33, "99S12D-40MA5-y" - is this connector a twisted pair connector ...
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2answers
67 views

Please help me perform DC analysis of the attached circuit and derive equation for VB (Q1)

I am designing a differential pair with single supply source (Vcc), and I am very particular about not using split supply. I am using discrete current source for setting the tail current, and biasing ...
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2answers
75 views

I2C over long distance with RJ11 CAT3 cable: how EMI noise will effect differential (but not twisted) pair wires

I have several nodes with Cat3 RJ11 cable in my office. I need to do an I2C communication between several nodes over + 20m and read about the PCA9615 driver. Unfortunately, the Cat3 RJ11 cable has ...
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1answer
86 views

ICs on opposite sides of a PCB

I am relatively new to PCB design and circuits in general. I am routing my first 4 layer board now and I am wondering about placing ICs on top of each other on opposite sides of the PCB. The ICs in ...
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50 views

Driving optocoupler by a line receiver

I wanna drive TLP350 by a line receiver AM26LS32. I employed scheme 1, however, there was no signal on output. I found in line receiver datasheet that the current sign is negative so it is likely to ...
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2answers
64 views

What is Ethernet diff. pair referenced to between connector and magnetics

This is a little bit confusing part. I clearly understand that in ethernet cable fields are coupled between wires of differential pair. On PCB on IC/PHY side it is also known that differential pair ...
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2answers
207 views

Differential pair active load contradiction

I'm confused about one current-based explanation for why the active current mirror restores a differential pair's gain by letting each differential input reinforce the other. The explanation (from ...

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