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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2answers
253 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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3answers
160 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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4answers
4k views

Can anyone explain this balanced driver circuit to me?

I'm looking to generate a differential signal to control a laser projector's galvos, and as I understand it needs to be +5V/-5V (10Vpp). I've found this circuit for a laser harp, but I'm confused ...
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1answer
163 views

Why do we need differential amplifier after Transimpedance amplifier?

I am implementing the circuit published in AN3025 Transimpedance Amplifier Design as shown below. When I am simulating this circuit, a few questions come to mind: Q1. Why do we need a differential ...
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1answer
58 views

Understanding different crystal designs

I'm having trouble understanding around how this crystal design works: They place a capacitor between the XI and XO pins (is this called a load capacitor?), whereas all other crystal designs I've seen ...
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2answers
43 views

Fully differential opamp with transformer coupled input voltage

I want to amplify / buffer a transformer coupled voltage with a fully differential op amp. When using e.g. instrumentation amplifiers with a transformer coupled input voltage, one side has to be ...
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1answer
32 views

Differential Pair routing insight for USB 2.0 circuit involving a USB C connector with multiple D_N and D_P pins

I'm bringing USB 2.0 into a PCB design from a USB C receptacle. I've already accounted for the 5.1k resistors needed but I'm stumped on how best to run a differential pair with DP1, DP2, DN1 and DN2 ...
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2answers
201 views

Why don't I get the right values for Vout=Gain(v1-v2) for this differential BJT amplifier?

I am trying to use the formula that they have mentioned Vout=Gain(v1-v2), in my simulator I have placed one signal at 0.001V and the other one at 0V. The gain that they have found is 192, so I expect ...
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1answer
207 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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1answer
314 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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1answer
48 views

What is the difference between “differential” and “differential-coplanar” in controlled impedance?

I am routing differential pairs in Altium 20 and using controlled impedance profiles. I am using microstrips on external layers only. For instance, I want a 100 Ω controlled impedance pair, and have ...
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3answers
209 views

Measuring voltages from different sources sharing Common ground that might differ slightly

I have a design with resistor dividers and low pass RC filters dropping down 0-32V to ADC range of 0-1.8V. With multiple channels, I attempt to measure voltages from different voltage sources on a ...
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1answer
664 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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1answer
73 views

Differential Square Current generator LTspice

I am trying to model a square wave differential current generator in LTSpice for MAX30001 IC, refer page 6 for the specs. Specifications: Differential Square wave, Amplitude : 8 to 96 uApk and ...
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1answer
44 views

Altium Designer - How to change width and gap of differential pairs without rerouting?

As the title already states, is there a way to change the width and espacially the gap of a differential pair after routing? In Altium Designer you can easily change the width of both of the ...
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1answer
36 views

How does differential mode noise and common mode noise occur

I was reading this article on common mode and differential mode noise. But it is not mentioned anywhere on how the differential mode noise and common mode noise occurs. From the diagram, I kind of ...
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0answers
66 views

How to recognize a symmetrical circuit

I'm reading a book (Vatché Vorperian's book on the extra element theorem) and there is a problem which states : I found solving this problem interesting. However, the hint is most useful for other ...
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6answers
553 views

Differentiator and integrator - without op-amp

I am trying to understand the working and function of the integrator and differentiator circuits using op-amps. Can someone tell me why we need to use op-amps for that function? Selecting just the ...
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2answers
215 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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1answer
49 views

Routing ethernet differential pairs over ground plane

I am routing a flexible PCB which connects a panel-mount ethernet connector (without integrated magnetics) to a rigid PCB which contains the ethernet magnetics. I plan to route the differential pairs ...
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0answers
26 views

How to improve this bypass switch from floating/differential to grounded/single-ended with just one DPDT?

This is for use in guitar onboard active electronics. (i.e. battery powered, installed in the guitar.) I want to be able to switch between: Differential input (to Op Amp circuit) with pickup coil ...
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5answers
100 views

Do differential ADC's really reject 100% of common mode noise?

Say you have differential signals that are perfectly phase and amplitude balanced, but obviously 180 degrees out of phase V+= Asin(2pif*t)+ Vcommon_mode_noise V-= -Asin(2pif*t)+ Vcommon_mode_noise The ...
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0answers
23 views

Designing Differential amplifier with differential output

I have done calculations for designing a differential amplifier (DA) with differential output. I simulate (using cadence ) the DA with the calculated values and perform the DC analysis of the circuit ...
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4answers
155 views

Frequency response of difference amplifier

I'm studying the difference amplifier circuit configuration of op amps, reading from this datasheet. I know that unlike the instrumentation amplifiers, the difference amplifier differential gain can ...
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1answer
426 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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1answer
47 views

STM32F303 ADC Differential Mode Offsets

I am trying to configure ADC1 on the STM32F303RE Nucleo board and I have not been able to find any good documentation on how differential mode works. I used CubeMX to setup the HAL with ADC1 Channel 8 ...
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3answers
364 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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1answer
329 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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1answer
165 views

Calculating the gain in a differential amplifier

I have a specific question regarding this circuit: I need to calculate the gain of this amplifier. However, when I do this, I get the value two times bigger than the simulation of this circuit, which ...
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2answers
247 views

Locally hatched ground plane to increase differential impedance

I am designing a flexible PCB to carry two types of differential signals. One is about 1.2Gbps 100R differential impedance, while the other is only 3Mbps, with much more tolerance on the impedance. ...
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2answers
70 views

Problem with op amp output hitting bottom rail on output stage for DIY 3D printed strain gauge. High gain is needed

So the goal is to take our differential input from our experimental full bridge strain gauge and amplify the signal to a gain of roughly 5500. The output signal would then be going into a 12-bit ADC ...
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2answers
52 views

Read 4wire pressure transducer via a differential amplifier

I have been trying to read a 4wire pressure transducer (M3021-000005-01KPG) with a microcontroller, but problems keep arising. First of all, I realized that the signal (0-100 mV) is differential, ...
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1answer
69 views

Capacitor stitching for high speed differential pairs

This is the first time I have designed a 4 layer board and the reading I have done says to use stitching vias for the differential pairs due to the stackup I am using. The stackup is as follows ...
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1answer
193 views

Simulating PMOS differential amplifier in Cadence

I am studying about rail-to-rail opamp design and I am trying to recreate the Itail vs Vgs (in this case input common voltage) curve from the link bellow (pages 5 and 6): https://mixsignal.files....
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0answers
68 views

Gmo2 from vout about differential amplificator

I'd like to know if this demostration is correct to calculate Gmo2 from vout about differential amplificator from this diagram : 1 : Gmo transconductance about Common Base configuration 2 : Gmo1 ...
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1answer
24 views

Common mode (CM) and differential mode (DM) filters components reduction

I have a 24VDC system where I have designed common mode (CM) and differential mode (DM) filters. As system works with lower voltage I use TPS54560 buck regulator. The goal is low conducted emi. ...
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1answer
36 views

differential amplifier mismatch of transistor values

I am studying differential amplifiers and I am confused that when mismatch occurs in gm or RC in BJTs or gm and RD in mosfets, in book it carries out calculations as if the transistors are matched. ...
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1answer
50 views

Differential pair on a PCB region without a reference plane

I was reading the datasheet for an Ethernet interface layout from NXP and I found they didn't use a reference plane in the region where they routed the differential pairs. I couldn't understand why ...
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2answers
159 views

Amplifier output goes haywire with load attached

I'm trying to create an op amp using FETs and BJTs. I need the gain to be over 500, currently without a load attached I have the gain about 1000. The input is a 0.05V sine wave, the output is ...
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0answers
31 views

LPF based Differential demodulator design

I am designing LPF based differential demodulator(LPF_DDM) to retrieve differentially modulated signals, which are on-chip capacitive isolated [shown]. LPF_DDM includes a differential amplifier, LPF, ...
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2answers
51 views

Balanced Audio Line Driver Off Single Supply

I am working on a device that needs a balanced audio line driver that can convert an unbalanced signal to balanced and drive a balanced cable run between devices. I am looking at schematics using ...
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1answer
51 views

LTC5599: why are these baseband inputs passed through 49.9 ohms and the capacitor + SPI

I'm designing a radar transceiver board using the LTC5599. In the datasheet for the part, there is a schematic that shows the circuit configuration for the evaluation board. Here is an image of the ...
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1answer
40 views

RF output matching using baluns: LTC6946

The datasheet that I refer to below can be found here: https://www.analog.com/media/en/technical-documentation/data-sheets/6946fb.pdf I have a question about baluns. In the datasheet for LTC6946 ...
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2answers
2k views

Ground loops with balanced connections?

Different articles and tutorials provide somewhat contradictory information about ground loops. For a balanced (differential) connection, the return path is "the other wire" in the ...
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1answer
85 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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2answers
392 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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2answers
839 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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3answers
407 views

Advice for 90 Ohm traces of a USB 2.0 HUB

I am designing a USB-hub that has many USB traces. I followed some guidelines online and read forums. Based on my understanding of a 4-layer stack-up, one of the best set-up I chose is 8 mil trace ...
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3answers
93 views

In a differential pair BJT amplifier, the individual gain of the transistors should be equal. Why am I getting different gain for each transistor? [closed]

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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