Re: Mitigating Signal Reflection

On Mon, 18 Mar 2024 00:12:14 GMT, Dan <dan@nospam.invalid> wrote:

I'm new to electronics and I'm hitting an issue beyond my skill set. I
should start by saying I'm not 100% sure signal reflection is the issue,
but it's my best guess.
>
I have a 3.3V clock signal that I'm trying to convert to 5V. The clock
speeds are sub 100 kHz. I'm using a TI level shifter, TXS0108E. Looking
at the signal on a scope, it's a clean signal on the input and output
side when I don't have anything connected on the output side.
>
When I hook up the clock signal on the output side, over an
approximately 1 meter wire the signal on the scope is full of noise. The
scope also says the frequency is much higher than one the input signal
should generate. I see the noise push through to the input side. I'm
assuming this is because the level-shifter is bi-directional.
>
I've tried a few failed solutions, like using a diode to try and block
out the reflections, but so far no luck.
>
Any advice on how to deal with this?

Using a twisted pair for the signal might make sense. Running the
wire close to the system's metal container, or test bed ground plane
is also advised.

Where's the ground lead on the scope connected when you're
making these measurements? It can introduce gound loops.
If the noise/problem goes away when the the scope's disconnected
it's an indicator.

RL