A lot of devices have a low output impedance so that the signal can be split
using a TEE adapter with little loss or need for a distribution amplifier.
However, the cables must be impedance matched at far end, scope input, to
prevent reflections which are the source of the ringing.
You can
Is there any reason (other than cost) not to both series-terminate the
source and parallel-terminate the sink?
When I was dealing with analog video, the standard distribution method was :
1. Buffer amplifier with high input impedance, very low output
impedance, and a gain of 2 (so 1 V P-P
Hi Dave,
yes there is a reason.
The standard 1PPS signal termination (Thunderbolt etc) used to be 5 Ohms
or less series termination into a 50 Ohms coax (yikes), then end-terminate
to get rid of all the undesired reflections.
Your example below is properly terminating a 75 Ohms coax with
I will agree that the end termination is optional if you are delivering a
pulse signal to just one input, which is at the far end of the coax.
However, I think there's still a problem with series-only termination when
the pulse signal is daisy-chained through multiple inputs. When you apply
5
Hi Dave,
what you are describing is reflected wave switching, which works perfectly
in applications such as the PCI bus. The PCI bus uses it because it lends
itself to extremely low power consumption.
Your scenario does not work with end-termination either if you have
multiple taps,
dave.martind...@gmail.com said:
Is there any reason (other than cost) not to both series-terminate the
source and parallel-terminate the sink?
With both series and parallel termination, the signal at the receiver is 1/2
the output level of the output driver. That doesn't work well if you
Hi
These are saturated logic signals. When you terminate both source and load you
get an interesting issue with compatible logic levels.
For instance: 5V CMOS switches at roughly 2.5V. If you series terminate and
load terminate, your destination now sees a 0 to 2.5V signal. Either it’s
depend how do you terminate the, cable if the cable's impedance is Z,
use two terminating resistors each R =2Z, one is connected to thee
ground the other is connected to the supply voltage of the receiving
chip, that way although the cables input and output termination will
eat up half of the
