Questions tagged [termination]

The matching device placed at the end of a trace that is acting as a transmission line. This termination prevent reflections from the end of the line and ensures a complete transfer of energy in the waveform into the receiving unit.

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Does forward termination of a cable hide the capacitive load?

I stumbled across this claim in the datasheet of the TLV3541 opamp: The TLV354x output stage is capable of driving standard back-terminated 75-Ω video cables, as shown in Figure 23. By back-...
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USB Data Line Current Value

I am designing USB2.0 hardware input but i don't have enough space on my PCB area. I searched many site but I cant find any information about D+ D- data lines power consumption. I am using 15R ...
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Why do we need to use a 100ohm differential probe to measure ethernet signals when there is not any standard?

I was going through the debugging techniques of ethernet signals and found that we can capture the ethernet signals using a 100ohm differential probe. Why do we need to add 100ohms on the ...
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DDR3 Termination Resistors and VTT Capacitors

I have a DDR3 implemented in our current design with 50 Ohm 0402 termination resistors and 0.1uF 0402 decoupling capacitors to VTT on the address, data and control lines. The design is working well ...
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CAN bus termination resistor

I'm trying to design a CAN device where the user can select which device is the beginning/end device and activate the 120 ohm resistor accordingly. I've seen some examples using a switch, but I'm ...
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What's the signal seeing on the output - 50 ohm?

Hi, I'm designing an OP amp circuit. I would like to terminate the output with 50 ohm because the device will be a measurement device with an oscilloscope or DUT on the iutput. Left side is basically ...
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How Does an Adjustable Transistor Size CMOS Driver Work?

Background The source-terminated reflected wave switching scheme is a familiar one. One just needs to add a source-series terminator, which added together with the driver's output impedance equals the ...
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RIN measurements of a laser

I want to measure the relative intensity noise between 0 and 1 MHz of a laser using a photodiode (20 MHz BW), a voltage amplifier (10 MHz BW), and a spectrum analyzer. Since I don't have so much ...
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Help needed with determining PCB trace termination for µC/SDRAM interface

I am trying to figure out whether I need termination resistors for my PCB routing between a µ-Controller and an SDRAM (IS42S32800J-6BLI) that I plan to clock at 166 MHz. According to Table 72 of ST's ...
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Line termination for single-ended to fully-differential conversion

I am trying to convert a single-ended signal from a sensor to a differential one by using THS4500 from TI. The output of the sensor goes through a buffer before being connected to the fully ...
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ESP-PSRAM64 Termination Resistors

ESP-PSRAM64 uses a bidirectional QuadSPI interface at up to 133MHz. I am connecting this to an STM32 microcontroller. Normally I would use some series termination resistors at the source (e.g. for a ...
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How to terminate branches in a transmission line

some research has unfortunately not led to a clear result. Branches in transmission lines are not desirable, but if they are unavoidable the question arises how to properly terminate the individual ...
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Why is the tip of my PL-259 connector sheared off?

I recently ordered a cable with a PL-259 termination and when it arrived I saw that the tip of the plug had been sheared off and at first I thought it was defective and went to return it or downgrade ...
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Bi-directional Line Termination using series resistor (s)

I am designing a PCB for an ST micro MCU with external SDRAM. On the demo board, ST is using one(1) series resistor termination for the bidirectional data lines. ST places this resistor at about 30/70%...
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How can I bridge across a change in differential impedance?

In a design I'm working on, I have a 100Mbps differential signal traveling from a chip on one PCB to a chip on another PCB. For various reasons, I can't make the differential impedance the same on ...
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Can a node on a terminated end of a CAN bus self-identify that it is the final node?

Using the example below, is there any way for Node1 or Node3 to be able to recognize that they are the final nodes on the CAN bus? I want to allow my device to automatically enable a 120Ohm ...
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Parallel Termination:FLY-BY Topology

I was simulating fly by topology. I can see that the Rise time and fall time is better for the receiver which is near to the termination resistor. May I know why is it like that.
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Why for DDR3 driver with a low-impedance output undesirable?

I was reading Micron's TN-41-13 DDR3 Point-to-Point Design Support technical note. It says the following on page 7: In point-to-point designs, the memory’s position is typically quite close to the ...
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Level Translator Impedance Matching Termination Resistor For High Speed?

I want to connect level translators like 74LVC1T45 to a microcontroller to translate high speed signals from 3.3v to 5v. I want to make sure it works for frequencies up to 40 MHz. The traces on the ...
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Oscilloscope impedance mismatch issue

We have connected an oscilloscope and a function generator using a connector plate. We have terminated the signal connections from the oscilloscope & the function generator to the connector plate ...
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Series termination on an input pin?

On a development board, I found this schematic for an up to 100 MHz clock input/output pin hooked up to a 2.54 mm pin header block: The 22 ohm series termination makes sense if the pin is configured ...
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DDR4 clock termination

In many places I have seen that an AC termination scheme is recommended for high speed clock termination. What is the reason for choosing this scheme? For AC termination, can a capacitor be connected ...
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Termination resistors using bipolar transistors for RS-485?

I am planning to use RS-485 on a network and I do not have too much experience on the standard but I understand that termination resistance must be provided for considerable lengths and transmission ...
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Matched termination of a microstrip using absorber foam

I have open ended microstrips in an RF circuit (operation freq. 18 GHz) and they cause unwanted back reflection into the rest of the circuit. Now, I wonder if it is possible to eliminate / reduce ...
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How to terminate Shield of USB connector to System Ground via Resistor || Capacitor or Ferrite Bead?

I want to know the best approach to connect USB connector's (receptor) Shield to System Ground? Below are the two options. PC(Earthed)<----- USB Cable ----> USB Connector female(PCB with NO ...
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Termination Regulator for DDR4

I went through a previous Industrial PC Motherboard design in my company where Ritchtek RT9045 was used for DDR4 design. it's clearly recommended tat this device is ideal for DDRII/DDRIII in the ...
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Capacitive coupling Ethernet on backplane

Sorry in advance I am fairly new to the electronics world and Ethernet signaling. I am a physics postgrad student doing some hardware work rather than an electronics engineering background. I have to ...
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CAN physical layer fault conditions Short circuit to battery on CANH and CANL lines analysis

In case of short circuit to battery on CANH, would the current flow as analysed below ? This is in the case of CAN transceiver TJA1042T and I got the internal block of the transciever by NXP. Data ...
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Resistor on outgoing signal lines - the logic behind it

I've been reading a lot and also been advised to place a series resistor (order of 33 - 45 ohms) on outgoing signal lines. Also called a termination resistor I believe. Example on this topic: Series ...
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Feed-through termination

I have a very basic question about rf-electronics: I tried to understand how feed-through terminators work, but I could not find a wiring diagram online. Intuitively it would make sense to me if such ...
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328 views

Star configuration using CAN Bus, I2C or RS485

I need to create a sensor network, with a central node receiving data from +10 different nodes, each one +20meters from the central node. So basically I need to create a star configuration, with a ...
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Why does FPGA PCI Express Tx output have on-chip termination of 100 Ohm?

The Intel Cyclone IV FPGA supports PCI Express (PCIe) generation 1, and the IO standard for the Tx output is PCML at 1.5 V. The Cyclone IV Device Handbook volume 2 page 1-13 describes that the Tx ...
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Series resistance on crystal

I have an STM32 chip with a 12MHz crystal connected to it (as seen in the figure below.) I've been advised to place a 220 ohms resistor 'in the OSC_OUT connection'. I know it has to do with the ...
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When do you need a complex termination?

The formula for the characteristic impedance is below So the characteristic impedance is a complex number. But why is a complex termination generally not used? With complex termination I mean a ...
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Considerations for CAN termination resistor location

I'm looking to incorporate a switchable 120Ω termination resistor (using a photo MOSFET) into a CAN design. Are there any issues with locating the 120Ω resistor at the CAN transceiver versus at the ...
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CAN Stub node termination in a network - 9.28k resistor

In a CAN network, the ends of the network has to be terminated with 120 ohm - I understand this. The middle node in the below diagram is the stub node and it does not have to be terminated, my stub ...
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Clock signal Series Termination

I was reading about the series termination techniques. I have seen many schematics with 33E series termination for clock signal. Can anybody please let me know why 33E is used & what happens if ...
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LVDS Termination - Not sure what it accomplishes

I am looking at the following schematic where there is an LVDS to LVDS connection. The common mode and swing are a little different between the output and the input. I am use to seeing 100 ohm ...
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SGMII Termination - Not understanding recommendation

I am going to be using a processor that has a few SGMII interfaces. From what I understand, these interfaces have LVDS logic levels. I am not use to seeing the termination scheme as recommended below. ...
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where should I place the terminations resistors for RS485?

I want to add termination resistors in RS485 bus . My systems is Multi-point ( the MCU can send to/receive from 3 external devices) I found out from this RS-485 CABLE SPECIFICATION GUIDE. that I need ...
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Oscilloscope amplitude reading depends on cable length? Reflection help

Suppose I have an RF source with 50 Ohm output impedance. First lets imagine the RF source outputs a low frequency 10 kHz signal (electrical wavelength is about 20 km). Suppose I have a 50 ohm coax ...
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1 answer
612 views

CAN Split Termination Capacitor Calculation

I'm trying to use the split termination on a CAN bus, but I'm a bit confused about the calculation for the split termination capacitor. It is described in Figure 10 in the Texas Instruments app note ...
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No terminations on point to point DDR3?

Are terminations required for DDR3 in point to point designs? I saw a reference design that doesn't include any termination to VTT for a controller/single DRAM design (pt to pt). DQS, DM and DQ use ...
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RS485 slew rate limiting remove need for termination

In regards to the highlighted feature of "slew-rate limiting" RS485 ICs. It says in multiple brand datasheets that the slew-rate limiting helps with transmission errors when there is ...
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Terminal resistor function on JTAG SMT2 schematic

I'm studying the Digilent JTAG-SMT2 datasheet, in particular the schematic of Example 3 (Interfacing a Zynq-7000 while retaining the Xilinx JTAG Header). I have a doubt about the function and value ...
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Unused output of LTC6957-4 (or LTC6957-3)

The LTC6957-4 has two complementary CMOS outputs, and I only need one. What do I do with the unused output? My goal is to minimize noise on the used output signal, REFCLK_OUT. The datasheet is clear ...
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852 views

Selectable CAN bus split termination

I am designing a CAN device where the user may switch between it being the end device and thus with terminators or vice versa. Now, there is no need to drive it digitally using MCU, I would actually ...
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RS485 Pull-up, Pull-down and single termination resistor

Currently I use for Modbus RTU via RS485 with a shielded cable length of about 5 meters and a bitrate of 19.200 bit/s. Wired are 680 Ohm pull-up (A->+5V) and pull-down (B->GND) resistors near to the ...
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Does the standard termination of 120 ohm really suppress reflections in recessive state in CAN?

Suppose we have a multi-node CAN network with the ends of transmission line terminated with the standard 120 ohm. When the recessive state is on the transmission line, the voltage on both CAN_H and ...
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2k views

Terminating Resistors on Ethernet Port

I'm using Ethernet (CAT5/5e/6) cables to communicate with the PCA9615 Differential I2C buffer. These cables roughly have a characteristic impedance of 100 ohms, but I have a few questions about ...
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