All Questions
Tagged with impedance-matching termination
21
questions
8
votes
4
answers
1k
views
Impedance matching and termination resistor
I’m a little confused regarding impedance matching with resistors.
As far as I know, the impedance of a trace is a part of its characteristics and it can’t be measured with an ohmmeter. For example, ...
1
vote
0
answers
266
views
Impedance matching 133 MHz - Topology and terminating resistor concerns
I am using the QSPI bus of the RP2040 to talk to a flash chip. I am also putting 8 more chips (PSRAMs) on that bus in my design, and a second RP2040 to load them. The datasheet for the RP2040 isn't ...
- 671
0
votes
0
answers
211
views
How to correctly terminate a TTL line between two ICs?
I am designing a circuit to convert a 5ns ECL signal to an LVTTL signal of >10ns. The SY100ELT25 is used to convert the ECL to 5V TTL which is then fed into the SN74LVC1G123 to further reduce the ...
- 65
0
votes
3
answers
1k
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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 ...
- 319
0
votes
1
answer
217
views
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 ...
- 29
3
votes
1
answer
105
views
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 ...
- 31
0
votes
1
answer
478
views
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 ...
1
vote
1
answer
1k
views
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 ...
1
vote
2
answers
753
views
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 ...
- 11
1
vote
0
answers
58
views
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 ...
- 13
3
votes
0
answers
173
views
Eliminate reflections on pulse signal transformer
I am trying to isolate an RLC ringdown signal via an RF signal transformer but I'm having trouble maintaining the signal integrity through the transformer. Below is the simple schematic describing my ...
- 419
1
vote
0
answers
441
views
Impedance for TTL Hsync and Vsync Pulses
I'm just finishing up a sync combiner and audio/video PCB. I'm trying to impedance match my traces and I've done so for the 75 ohm RGB lines. Now I'm looking at the TTL level Hsync and Vsync lines ...
6
votes
3
answers
3k
views
With parallel termination of a transmission line, why does the receiver see the full voltage?
With parallel termination of a transmission line, the line characteristic impedance \$Z0\$ is matched with the pull-down resistance \$Rt\$. But, in that case, shouldn't the receiver see half of the ...
6
votes
1
answer
3k
views
Why is the signal amplitude low on the oscilloscope even though the impedance is matched?
I have a photodetector with differential outputs that are each 50-ohm terminated.
When I connect one output to the oscilloscope to look at the signal, I see a higher signal amplitude with higher ...
- 215
10
votes
3
answers
4k
views
RS485 termination: AC + failsafe + parallel + bidirectional
Knowing that I need to refine my RS485 circuitry, I've been reading. I have a series of specific questions and I hope that you'll indulge me as I describe how I attempted to follow through an ...
- 3,229