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 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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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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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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57 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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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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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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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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98 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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71 views

Current transformers, voltage output vs current output

I'm designing a energy monitoring system that is using split-core clamp current sensors to measure multiple high power lines(40+ lines at 300A each) in a MCB room of a building. I'm currently sourcing ...
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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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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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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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29 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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287 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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637 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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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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225 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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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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185 views

Using common mode choke in differential configuration for differential mode EMI filtering

Why is it not popular using common mode chokes in differential mode configuration for differential mode noise filtering? Mostly when using fly-wire type chokes with filters, where the chokes are ...
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47 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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633 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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380 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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147 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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23 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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74 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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196 views

Op amp output voltage swing vs noise

Staying within an op amp's specified output voltage range, how does a difference in output swing affect the op amp's noise applied to the output signal? Obviously by increasing gain, we amplify the op ...
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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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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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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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113 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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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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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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36 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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951 views

Damping resistors on HDMI Input

I’m working on a new PCB design using an Mstar LCD controller (MST9812Q1). I can’t link or post a datasheet as everything has “confidential, for internal use only” plastered all over it. The ...
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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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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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66 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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209 views

Proper way to connect signals to USB Type-C receptacle

I am trying to follow the design in this schematic link at page 9. The schematic above is connecting only RX1 TX1 and D1 data lines on the USB-C receptacle. And there are no pins shown for the other ...
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67 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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701 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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31 views

Differential transceiver SN65C1167

I have a question about a differential transceiver. In my application I am using a MCU to generate PWM signals for a gate driver board (CGD1200HB2P-BM2). This board, however, needs a diffierential PWM ...
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63 views

Attenuation in the circuitry of differential vs isolated probes

Using this website as a reference for differential probes: https://circuitcellar.com/research-design-hub/high-voltage-differential-probe/ By Andrew Levido, Circuit Cellar The differential probe is ...
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103 views

Differential (RS-422) vs current mode signaling in noisy environments

I’m building some automation equipment for my shop that will be used in extreme noise environments (plasma cutting and TIG welding nearby, for example) and I’m trying to come up with the best ...
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74 views

Differential integrator vs standard

I want to integrate/amplify a very small signal (relatively short pulses of 100ns to 4ms, necessitate high-bandwidth components minimum 40MHz+). The capacitors will be switched (shorted) when not in ...
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Finite CMRR even with ideal tail current source (body effect)

In Razavi's Design of Analog CMOS Integrated Circuits 2nd edition page 123, the diff-pair below is included with a comment about how even if the tail current source is infinite, if the transistor pair ...
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34 views

Referencing multiple differential pairs to ground before analog multiplexer

Yesterday I asked how to properly reference a differential signal (in my case from a current transformer) to ground, and got told that the impedance to ground should be matched at the location where ...
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376 views

Common ground in low side current sensing

I've asked this question a while back and user/Transistor told me that the circuit will be floating and drift without a common ground, he suggested a virtual ground. but in this case we already have a ...
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84 views

Create differential signal from single ended encoder

I have a problem with the output of an DC motor encoder feedback. I have an 5v single ended encoder (AB signal), but my control needs an differential signal. I am not sure how to do this as I have no ...
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35 views

Differential pair linear range

If I increase the tail current, will the linear range of differential pair (range of Vid when both transistors are on) become larger or smaller? According to this formula, linear range will increase ...

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