Hi
All I am trying to develop a circuit that would enable an analogue signal (400kHz Frequency, 0V to 5V) to be transferred over wires to another circuit board, in a noise environment it is critical that it remains an analogue signal. I was thinking of using some sort of differential signalling circuit on one end (the source of the analogue signal) and on the other PCB a differential single ended circuit (Where the analogue signal gets reproduced). However I am a little unsure on what components to use and what kind of circuits I should be using can anybody guide me in the right direction with any suggestions for components/LTSpice simulatons?

Thanks

Art

 

Hi
All I am trying to develop a circuit that would enable an analogue signal (400kHz Frequency, 0V to 5V) to be transferred over wires to another circuit board, in a noise environment it is critical that it remains an analogue signal. I was thinking of using some sort of differential signalling circuit on one end (the source of the analogue signal) and on the other PCB a differential single ended circuit (Where the analogue signal gets reproduced). However I am a little unsure on what components to use and what kind of circuits I should be using can anybody guide me in the right direction with any suggestions for components/LTSpice simulatons?

Thanks

Art

How long of a wire? How about shielded coaxial cable.

Without knowing the details and what constraints you have, we can only solve your proposed solution, not your problem.

 

Hi 547.
Over what distance are you working with the cabling.?
How is the 400KhZ modulated?
E

 

I

Hi 547.
Over what distance are you working with the cabling.?
How is the 400KhZ modulated?
E

It's not over a long distance around 10/15cm, its from a current sensor which is measuring the output current of a half bridge, the current sensor has a bandwidth of 400kHz which I assume I should design for?

 

How long of a wire? How about shielded coaxial cable.

Without knowing the details and what constraints you have, we can only solve your proposed solution, not your problem.

It's not over a long distance around 10/15cm, its from a current sensor which is measuring the output current of a half bridge, the current sensor has a bandwidth of 400kHz which I assume I should design for?

 

Below is the LTspice simulation of a single-ended to differential to single-ended circuit.
That will minimize any noise between the two circuit board grounds from contaminating the signal.
Out1 and Out2 are the differential output to the second board, which contains U2.
This converts the differential signal back to single-ended (Out3).

 

Below is the LTspice simulation of a single-ended to differential to single-ended circuit.
That will minimize any noise between the two circuit board grounds from contaminating the signal.
Out1 and Out2 are the differential output to the second board, which contains U2.
This converts the differential signal back to single-ended (Out3).

View attachment 143834

Nice! ... is it safe to leave the negative output of U2 disconnected? (floating?)

 

Hi
All I am trying to develop a circuit that would enable an analogue signal (400kHz Frequency, 0V to 5V) to be transferred over wires to another circuit board, in a noise environment it is critical that it remains an analogue signal. I was thinking of using some sort of differential signalling circuit on one end (the source of the analogue signal) and on the other PCB a differential single ended circuit (Where the analogue signal gets reproduced). However I am a little unsure on what components to use and what kind of circuits I should be using can anybody guide me in the right direction with any suggestions for components/LTSpice simulatons?

Thanks

Art

Yes, there are a variety of differential line drivers available. RS 422/485 protocol is useful over a few thousand feet. Look into the standard equipment available before trying to design your own! We used -422 under the harshest conditions imaginable at Hipas Observatory and HAARP.

 

is it safe to leave the negative output of U2 disconnected? (floating?)

I would assume so.
You can connect a load to ground if it makes you feel better.

RS 422/485 protocol is useful over a few thousand feet.

That's a digital signal, not analog.

 

You can connect a load to ground if it makes you feel better.

I'd use a resistor for that... but then again, I haven't read the datasheet...

That's a digital signal, not analog.

yeah... I was gonna say...

many thanks!

 

I haven't read the datasheet...

I saw no particular mention in the data sheet of whether leaving a output unconnected is a problem.

 

I would assume so.
You can connect a load to ground if it makes you feel better.
That's a digital signal, not analog.

but the actual hardware is pretty much the same:
http://www.analog.com/en/products/a...-5-video-drivers/ad8131.html#product-overview

 

but the actual hardware is pretty much the same:

Depends upon your definition of "pretty much the same".
RS 422/485 hardware is optimized to transmit a two-level digital signal.
Superficially they may seem similar but the internal circuit is significantly different if it needs to accurately transmit a continuous level analog signal.