low voltage signals over a connector

[fuuton]

Hi,

I am working on a PCB where I need to route 25mV signals with low current (uA) to another board. I am concerned about noise and signal degradation when these signals pass over a board to board connector. Any suggestions on connectors?

Are there existing methods to be used in such a scenario?
Are there special connectors which can be used for this purpose?

Thanks in advance

 

[KlausST]

Hi,

i recommend to amplify the signals.

**
If not possible: use a second signal (maybe GND) as reference.
It should:
* have the same impedance on both ends.
* be routed close to the other signal (as long as it is not HF).
--> All errors (thermal, inductive coupling, capacitive coupling) should influence both signals in the same way and magnitude.
--> A differential amplifier at the receiver side compensates a lot of influence.

Klaus

 

[D.A.(Tony)Stewart]

IN the old days, it was common to have feedthru connectors with shielded pins and capacitance to ground to prevent egress and ingress. THese are quite expensive but often used by military for best signal integrity.

Depending on your signal bandwidth and impedance, you want to pay attention to external interference voltage and current induced onto your signals. Thus a combination of solutions may be used. Shielding, balanced common mode chokes for low and high frequency, and differential filters ( RC). Suppression can be estimated from Load/Source impedance ratio * unintended source voltage or current noise.

Ultimately you must define the SNR and BW you need for immunity and signal integrity. There are standard immunity tests from IEC if going into consumer environment.

 

[marce]

convert and transmit as Balanced (differential) signals...

 

[FvM]

Differential signalling as always a good idea.

We should get an idea of signal kind (AC or DC) and bandwidth. mV and µA refers to kOhm impedance, sounds like low bandwidth.

 

[marce]

If differential signalling is not possible then differential (balanced) routing is another option, preferably broadside coupled where possible for low level analogue signals.