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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What's the benefit of using 2 ground line (instead of 1) in a differential pair of SATA3 data cable?

The following is a sata3 data cable picture taken from wikipedia There are 4 wires for each differential pair, and I guess the two silver-colored cables are grounds, and the two bronze-colored cables ...
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Best way to drive high speed ADC with differential inputs

Currently I am using AD8137 to convert my single ended signal to a differential signal. The ADC I am using is ADC3422 from TI and the data sheet suggests a passive circuit to drive low frequency ...
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Instability of fully differential op-amp in LTspice

I tested the following circuit including a fully differential op-amp for stability in LTspice. The circuit has an inverting gain of 6 and a roll-off at 4 MHz. When exciting the circuit with a step, ...
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2 votes
3 answers
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What are the recommended CK, DQ, DQS, ADDR impedances for LPDDR4?

I am using a micron part with LPDDR4, in many datasheets from micron there are no references to a specific impedance for CLK, DQ, DQS, ADDR. The datasheet mentions that the LVSTL is tuneable, but what ...
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What is SN75176 receiver pin drive current?

I am poor at understanding what datasheet symbols denote. Please help me decode what might be the drive current of receiver logic pin. Here is the link to datasheet: https://www.ti.com/lit/ds/symlink/...
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Frequency response of a differential amplifier

I have to simulate the frequency response of the following differential amplifier: Here are the simulation results: The green graph represents (vin1-vin2)/vs and the red one represents (vout+ - vout-...
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Ethernet PHY RMII waveform without LAN Cable connected

Is the below waveform that I am getting in TX- line of Ethernet (PHY Used - LAN8700) correct? (Waveform obtained without connecting the LAN cable). Using RMII mode in the PHY. R801 & R803 (pin 1) ...
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Benefit of fully differential amplifier

I am trying to build an audio amplifier PCB with S/PDIF and single ended line level inputs and want to use the CS42528 CODEC (datasheet). My questions are regarding the input and output stages of this ...
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Ethernet differential signals

I've 2 questions on Ethernet design: Suppose I am using a current mode Ethernet PHY which requires termination resistor of 49.9 ohms to VDD on the Ethernet differential lines. Can I increase the ...
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LVDS voltage levels

LVDS terminology can be a bit confusing when noted that Vcm typically is 1.2V and Vd 350mV. Does this mean 350mV as in +/-350mV so (Vin+ - Vin-) is (2*350mV) or overall swing (peak to peak of a ...
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Differential Microstrip Impedance Calculators Giving Conflicting Answers

I am attempting to determine the trace width needed for routing a differential signal of 100 Ω on a PCB I am designing. This is a hobby project and the differential traces are for gigabit ethernet. I'...
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Formula for coupled stripline of 100 ohm

I am designing a PCB which involves MIPI and LVDS routing. What is the formula to calculate the impedance of asymmetric coupled stripline for MIPI and LVDS routing (100 ohm)? The required calculator ...
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Is this a legitimate RS485 wave shape?

I'm having issues but first of all I need to verify the other end of the communication line… there is a Moxa TCC-100 RS232-RS485 converter attached to the bus and I see this weird signal on the bus ...
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DC-coupled wide-bandwidth differential to single-ended conversion

I'm designing a circuit that produces differential signal outputs in the frequency range from DC to about 2 GHz. This differential signal will be driven by an FDA (probably LMH6401 or LMH5401). I'd ...
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Differential capacitive transducer

I would like to design a differential capacitive transducer to measure the capacitance change in an accelerometer. I cant seem to understand, how to demodulate the signal and keep the actual DC value....
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Length matching/differential pairs and distance to polygon and other layers

If you have length matching on the inner layer of 4 layer board: Do you need any minimum or maximum distance to the adjacent layers above and below? Are there any rules of thumb? Also is there any ...
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Correct Dielectric Height on Differential Impedance Calculation?

I'm designing a custom PCB around the Raspberry Pi RP2040 MCU. Their hardware design guideline said the traces between the USB and the termination resistors should have a differential impedance of 90 ...
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What can this CAN bus like protocol be?

I am currently probing what seems to me the CAN bus twisted pair of my car. But the signals are not what I expect. One of the pair is like a typical CAN HI signal, however the idle state is a 0V and a ...
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Differential signalling [duplicate]

This is a similar question to one over here. Posting a new question here, assuming that my question was not clear in that. Can we split a differential signal into 2? Assume the below image: I'm using ...
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RS-485 Network Topology with Backbone and Daisy-Chain Stubs [closed]

I am designing a RS-485 network and would like to know whether the configuration below would work. The transceiver I am using is the Maxim MAX485, with the master ad slaves hardwired to always ...
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3 answers
136 views

Splitting of a differential signal

Can the Ethernet Tx and Rx signals (Using all 4 pairs; RGMII interface) be split into 2 so as to connect to 2 RJ-45 connectors, but only 1 will be used at a time. In general, can we split any ...
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How do I make these MIPI signals better?

I have a system which transmits 1 Gbps single lane MIPI video over several flex circuits. Where each flex circuit connects to its neighbour, I have placed a MIPI repeater chip: SNx5DPHY440SS. At the ...
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What are the recommended differential trace characteristics for Power over Ethernet input section?

I've been looking through a few application notes for Power over Ethernet front ends such as Microchip AN3468 and Skyworks AN1130. I can't figure out what the characteristic impedance of the ...
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4 votes
1 answer
115 views

Characteristic impedance when routing differential

Can the characteristic impedance value of a single-ended transmissions line be omitted when the two transmissions lines of a differential pair are routed differentially (not two isolated lines)? I ask ...
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Is it possible to convert LVDS (TI DS90c241/124) differential signals to optical signals?

I have a circuit that uses the TI DS90C241 DS90C124 serdes pair to serialize 24bits of data from one board to the other. Either due to electrical interference or the transmission media's ...
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Logistic Growth in MATLAB -- Need help with the plot

I'm working on a school project about coding the logistic growth using matlab gui, till now everything is great, the calculation is perfect, but I'm stuck with the graph, it always show only one point ...
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Multiple conductors used for the same signal

I've inherited a design that has a pair of PCBs mated with two-row mezzanine connectors (0.5mm pitch, 2.5mm mated height) There are two differential pairs that travel through the connectors (RX and TX)...
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What is the function of a forward inverter and an inverted inverter in parallel in a digital circuit?

When I was simulating a divider using two D-latch as shown below (two D-latches in series,) I found that the circuit in the red rectangular is key to the differential D-latch. In fact, the circuit in ...
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1 vote
2 answers
60 views

What happens if you go below the minimum common mode voltage of a current sense amplifier?

This might be a simple one, but I can only seem to find information on going above the common mode voltage (VCM), not below it. Obviously going above the VCM upper limit will damage the device. I'm ...
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Oscilloscope "isolated" inputs

As I don't want to see my oscilloscope go up in flames when I play with probing circuits, I was wondering the following: First off, my goal is to measure different floating voltages aka the "GND&...
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1 vote
1 answer
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Differential voltage to frequency

Edited to clarify some questions I’m working on a design that will take a 0.5V-4V signal from a laser displacement sensor (Keyence Il-1000) and convert it to a frequency signal (0.1-2Mhz) for input to ...
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1 answer
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MIPI DSI/differential pair layout guidance

I have a display sample that I'd like to interface with a Linux SBC, the only issue is that the connector is not compatible. To make it possible to interface the two parts I've designed a PCB, trying ...
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1 answer
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Micro USB and RS485 Compatibility

I am looking into understanding micro usb better and seem to be missing something apparently obvious different about the difference between micro usb and rs485. From looking online like here, the ...
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1 vote
2 answers
45 views

ARINC429 - Help generating differential ouput with SN75172?

I'm trying to make a simple circuit setup to do a single-ended input to differential-balanced output of the ARINC429 spec, which is differential +5/-5v (10v p-p)... ie spec is explained better here: ...
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2 answers
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DAC differential output signal problem?

I'm trying to use a MAX5183 DAC to generate an analog voltage from a digital input. I have got it working in as far as the outputs follow the shape of the input digital waveform (just a sawtooth input ...
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2 votes
1 answer
123 views

Battery voltage measurement using ADC problem

I want to measure the open circuit voltage of an electrochemical battery using an ADC and an Arduino. I need to use the ADC in differential reading mode (A0 por positive and A1 for negative). ...
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Linearity Loss on Single Ended to Differential Circuit

I have a board that converts a single ended output of a DAC to a differential signal with options for the common mode voltage. The output of my 20-bit DAC goes on the VOUT_BUFFERED signal here. At ...
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1 vote
2 answers
96 views

How to protect differential data lines from ESD?

How do you protect a differential signal line (like Ethernet) without a common ground from high voltage or ESD? Do you use TVS-diodes from Tx+ to Tx-? I thought of using TVS-diode arrays due to their ...
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Intra Pair Length Mismatch Tolerance For 12.5Gbps signals

I'm making a high-speed transceiver design and want some direction regarding layout of trace length from P to N. The speeds will be up to 12.5Gbps. I have been informed by a equalizer manufacturer ...
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2 votes
1 answer
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Do I need to connect all pins of USB 4085 or can I use only the first row?

I would like to add a THT USB-C for hand soldering to my PCB. I found this on KiCad: https://gct.co/connector/usb4085 (Full schematics) D+ and D- are differential pairs. Do I need to connect all of ...
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0 votes
1 answer
106 views

voltage divider inside differential op amp configuration

I'm working on a DIY analog synth based on the CEM3340 chip. When feeding it 12V at VCC it will output waves at different amplitudes that I'll want to scale to 5V to -5V: Square: 0-10.7V Sawtooth: 0-...
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1 vote
1 answer
102 views

Why is the output impedance so high in my differential op-amp?

I tried to make a differential op-amp, but I get around 65k ohm of output impedance. I read online that op-amps should have ~50ohm to about maximum ~500ohm output impedance, but however I change ...
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8 votes
1 answer
905 views

What is this circuit called, and what is it used for?

I analyzed this circuit and found that it's an inverting amplifier and that the impedance of the circuit goes to zero when the frequency of the input voltage goes to infinity. Does anyone know the ...
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0 votes
0 answers
289 views

Differential signals in micro-coax

I have seen many applications where micro-coax is used for differential signals. For example display panels with LVDS or eDP, and a I-PEX VS type connector. The I-PEX connector even names USB4, HDMI ...
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How can I design a low cost fully differential op amp using a generic op-amp (audio purpose) [closed]

can I replace this fully differential Op-amp (OPA1632) with a generic op-amp based design ( Figure 2: Using NE5532). The Application area is audio signal handling. Input: Differential input / ...
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What are the voltage levels in 100 Base-TX Ethernet?

I know what the differential voltage looks like. If you measure across Tx+ and Tx- it goes from -1V to 0V to 1V and so on, but how are these voltage levels actually transmitted? Does Tx+ go from 0V - ...
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2 answers
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Single-ended digital signal to RS422 differential signal

I'm trying to control a laser scanner from an Arduino board. The Arduino outputs a single-ended digital signal 0V or 3.3V. The signal I'm transmitting to the laser is the same signal as I use to ...
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0 answers
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Single-ended to differential ADC driver with one pole active low pass filter

I have this ADC driver circuit: There is a passive filter downstream of the driver which works as desired. I'm focused here on the active filter. When I run AC analysis on this circuit configured for ...
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2 votes
2 answers
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Capacitive coupling for common mode rejection?

I'm not finding any information on this method, so I'm thinking that I must be missing something. I have a 5V single ended RRIO opamp that I need to measure BLDC motor current with. The motor is ...
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1 vote
3 answers
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Cable Shielding for Non-Isolated Differential Signals

If I am transferring data from one device to another using a non-isolated differential signaling standard like LVDS or RS-422 through a cable, and each device has its own single-point ground, should I ...
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