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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112 views

Generate +2V Offset on a +12VCD Supply line

I have a 12VDC @50mA_Max supply line. I need to inject a +2V 50us offset pulse to the +12VDC line, having an effective +14V for 50us. I have access to an external power supply, where I can have ...
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1answer
848 views

Mapping a voltage range to whole ADC range using opamps

I want to use a micro for measuring temperature using PT-1000 sensor for range -40C to 150C. I have come up with these draft information, I appreciate it if a pro person can confirm my thoughts are OK ...
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3answers
2k views

How do I find transconductance gm in this exercise?

We have the following exercise : I have questions regarding a) and b) For a) the solution is As for b) you can kinda see it in the above solution that IE=0.5 mA ,I think that this is because IE=I/...
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130 views

Why ADC Differential Driver feedback resistors are small in hundreds range?

I noticed that the differential ADC driver circuits always using small values for feedback network resistors, an example is shown in the attached picture. Can we use large Values for feedback ...
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1answer
655 views

What is the advantage of a current shunt ic versus a differential ADC across the shunt?

I'm trying to measure DC 25A across a .005 ohm shunt resistor. From my research I've found the TI INA169 which is a current shunt monitor ic. However the datasheet says it has a total output error of ~...
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1answer
2k views

Driving a differential signal from FPGA

Disclaimer: I am not sure if this is the right place to ask this. I am trying to create an sdram controller for the numato mimas v2 fpga. The board contains an LPDDR module (either the Micron ...
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3answers
7k views

Ethernet 100 ohm differential pair layout

I'm finishing off the layout of a board in Eagle which has a LAN8710A 100Mbps Ethernet PHY on it. The SMSC documentation is really pretty good but I'm stuck on the important detail of how to do the ...
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1answer
681 views

Parallel differential signals

I need to send some I2C data through RJ45 cable between Arduinos. One ATMEGA2560 as master and 1-4 328P's as slaves. I've seen some different configurations and I think for my application the solution ...
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2answers
2k views

What are the effects of single ended signals on twisted pair conductors?

I'm currently using a cable that has multiple twisted pair conductors. I'm attempting to send a several single ended signals down some of these conductors at a frequency of 12.5MHz. Essentially, I'm ...
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2answers
569 views

High Speed PCB impedance question

I am going to design a high speed digital design including an FPGA and GSPS A/D interfaced with multi-gigabit/s serial ports. But I have found the impedance matching problem a little confusing, My ...
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1answer
172 views

Choosing differential receiver IC?

I have a differential signal A which I would like to convert to LVTTL output X as follows: X = 1 iff A+ > A- + 50 mV. That is to say, X is '1' only when A+ is more than 50 mV greater than A-. ...
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824 views

Vout of differential amplifier as Vref of comparator

simulate this circuit – Schematic created using CircuitLab I am a beginner at circuit design, and I am having trouble using the Vout of differential amplifier as Vref of comparator. The other ...
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1answer
693 views

How to decide and calculate parameters for track on differential pair?

I am a bit lost about how to establish the parameters to establish differential pair routing. I am currently trying to route several differential pair and I am a bit new to this. I have searched ...
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3answers
2k views

Differential pair how to decide track width, spacing and lenght matching [closed]

I am currently routing a pcb where there are some differential pair: Speaker, Mic. How do I decide what should be the space between both tracks and what should be the width for the traces ? I add a ...
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1answer
141 views

INA155 reference pin not working

To test the INA 155 I gave a sine wave of amplitude 0.2 V p-p 100Hz. It was operated at 5 V single supply. The reference pin was connected to 2.5 V from an op amp buffer. There seems to be no offset ...
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2answers
524 views

Saturation in differential pair

I'm reading Analysis and Design of Analog Integrated Circuits by Gray & Meyer. In the differential pairs' chapter, there is this circuit and it says: Assume the collector resistors are small ...
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1answer
614 views

How to connect GND between both sides of a signal transformer

I am doing a test board to learn more about ethernet, differential pairs, etc. I understand that the transformer will isolate my board from the world. But I wonder how to design the termination ...
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2answers
2k views

How do I get Ad and Acm for a BJT differential amplifier?

In a practise exam question I am given a circuit of a BJT differential amplifier and told to show that these equations are true: I am told to do it using the hybrid-pi model. Here is a picture of ...
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1k views

Passives used in differential signal lines

My doubt pertains to the presence of passives in many differential links (say RS422, for eg). Consider the schematic below - In the above circuits , I see a capacitor in series with the differential ...
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2answers
537 views

Measuring a potentiometer with noisy power

I need to measure a potentiometer where the voltage supplied is very noisy and cannot be filtered. I run into this a lot in my work, but currently I'm trying to measure a steering angle potentiometer ...
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1answer
57 views

Differential ADC has stopped working

I'm using a differential ACD from Microchip called MCP3424 and an ATMega16 to make various measurements. Here is the schematic: http://picul.de/view/HoR Note: I have changed the values of R22 and ...
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2answers
591 views

Unbalanced differential pair in NE5234

I had a question in mind. I was reading "Design and Analysis of Integrated Circuits" by Gray and Meyer... In the edition 5 there is an analysis of a Low power OpAmp NE5234... In the second stage of ...
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1answer
3k views

Is my Bob Smith termination valid for Ethernet 100Mb/s?

This is my first ethernet circuit, and I am a noob in differential signal lines. That is why I want to learn with a "simple" circuit. I use the reference schematics from the LAN9512 usb to ethernet ...
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1answer
104 views

What does an impedance to a fixed potential mean?

I am reviewing about differential pair and this comes up a bit confusing. Could anyone explain the part "equal impedances to a fixed potential" here? What does an impedance to a fixed potential mean? ...
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1answer
157 views

Could anyone explain why differential biasing is easier than single-ended one? [closed]

The lecture says that differenial biasing is easier than single ended. Could anyone explain why differential biasing is easier than single-ended one?
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1answer
104 views

Power at the differential output

I was measuring the voltage at the intermediate frequency output of this tuner http://superkuh.com/gnuradio/R820T_datasheet-Non_R-20111130_unlocked.pdf using the oscilloscope. The tuner has a ...
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2answers
1k views

Multi-stage differential amplifier

What is the purpose of combining two differential amplifiers as in the figure below? The first differential amplifier is a single input balanced output and the second differential amplifier is a dual ...
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1answer
85 views

Some confusion about differential-ended data acquisition system

I have many transducers which all have single-ended signal outputs. I hook them up to a single-ended DAQ board. A board with 16 single-ended inputs. The DAQ bard is currently set to single-ended ...
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0answers
126 views

using the AD8475 as a single ended output

simulate this circuit – Schematic created using CircuitLab I am putting together my schematic and I am trying to figure out if I can use the AD8475 as a single ended output buffer. AD8475 ...
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1answer
3k views

Can I use differential I/O pins of FPGA as high speed comparator?

High speed comparators are rather expensive and speed is what FPGAs are very good at. On the other hand, FPGAs (in my case: XC3S400) have paired differential pins in each bank that their voltages are ...
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1answer
90 views

Virtuous: Differential Input Single Ended Output Design Enhancement

I am trying to design a low power, fully Differential Input Single Ended Output amplifier with gain of atleast 50dB. I am using a VDD of 1.5 Volts using MOSFETS. I want to have maximum swing and my ...
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1answer
57 views

Can you explain why is there zero voltage at the source of a differiential MOSFET amplifier?

Using KVL, KCL and circuit analysis, Can you explain why is there zero voltage at the source of a differiential MOSFET amplifier? In the textbook, they just state that because it's balanced the source ...
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1answer
355 views

Selection of filters (common mode and differential mode)

I am designing a flyback converter that works at an operational frequency of 100kHz. Now, I need 2 levels of filtering at the input phase viz - common mode filter and differential mode filter. The ...
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2answers
327 views

Low side current measurement

I have a system similar to the one given by schematic. There is a 12V battery used for supplying MCU board and couple of distributed boards(inverter/measurement network etc.). Since I want to measure ...
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1answer
747 views

Differential measurements with high voltage oscilloscope probes

This interesting post about differential measurements with a scope has raised a few questions in my mind. I have read about true differential scope probes and they seem to be very expensive. Would ...
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1answer
2k views

differential pair with current mirror load

I have a question regarding small-signal analysis of the differential pair with current mirror load. For Small-signal analysis, why is I(d2) = -I(s1) ?
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5k views

Do I need biasing resistors on the +/- lines for RS485?

I know I should have a terminating resistor on RS 485. Do I need biasing resistors on the +/- lines of an RS485 differential signal?
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2answers
5k views

GND plane close to LVDS differential pair?

I have two LVDS differential pairs on my PCB, running from a connector. On the connector, I have the following sequence of nets: GND LVDS+ LVDS- GND LVDS+ LVDS- GND This is as I have seen suggested: ...
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0answers
494 views

Piezo speaker driver not giving full differential voltage - why?

I am trying to drive a piezo speaker at 20kHz with maximum voltage swing from a 10V source. Previously I had used a square wave plus its inverse to give the equivalent of 20V across the speaker but I ...
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1answer
2k views

Single supply differential balanced preamp

I'm trying to build a single supply balanced preamp for an electret mic. To further complicate matters, I'd like to impedance balance the mic output to take full advantage of the preamp's noise ...
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2answers
916 views

Common mode voltage elimination at differential pair receiver

Can you please explain to me how is common mode voltage of differential pairs is eliminated at receiver side? For example, if on RS422/485 bus there is more different transceivers (drivers and ...
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1answer
1k views

Single ended to differential amplifier workings

Hello electronics experts, I do not yet have enough reputation to post more then two images. For the images please see: http://imgur.com/a/dizis I have a single ended signal that i want to convert ...
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1answer
303 views

What are the concerns when converting single-ended signals into differential?

Application Description: We are converting a single ended DAC output into differential. The DAC output composes a DC signal(-10V - +10V) and sine waves running below 100kHz(below 100mVpp). The DAC ...
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2answers
4k views

Internal USB (FFC?) cable with 90 Ohm Differential impedance

I'm trying to run USB D+/D- signals and some unrelated 19V power between two PCBs, on the daughter PCB the USB D+/D- will terminate to a USB-A-F jack. I have no problem maintaining 90 ohm differential ...
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3answers
7k views

Current split between resistor and capacitor in parallel

I'm interested in knowing the formula which represents the voltage across the 10 ohm resistor. I know that it's going to be the current multiplied by the resistance, which means I have to find the ...
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1answer
96 views

How does an ADC with an unequal split supply work?

I'm having some trouble verifying my thought process for how a differential-input ADC works, especially when done in a case when run off an unequal split supply. I'm hoping to get some clarification ...
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3answers
943 views

What is the advantage of analog subtractor/summer?

Why we use opamps like in figure 2 instead of just add or subtract signals from each other as shown in the first figure? Is this choice differ if I apply DC signal instead of AC one? Sorry if this is ...
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2answers
7k views

USB signal routing - Swap data lines using vias?

I'm making my second USB design, but the D+/D- pins on the MCU (atemga16u2) aren't in the right order for the micro B connector. What's the best practice for routing these to go the right way? My ...
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2answers
60 views

Keeping inputs to opamps

I'm trying to get the hang of op-amps, and I've run into a stop. I'm trying to implement a differential op-amp, where the two inputs are from a wheatstone bridge. Please see attached diagram The ...
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1answer
355 views

Subtract Diff-Signal (Millivolts range) on top of common mode voltage (volts) with opamp - very inaccurate

I built a subtractor circuit as shown here with 10k each resistor. Now I want to measure current by using a shunt between the two inputs and letting a current flow through it, see here, figure 4, the ...