TMUX1111: Leakage Current

Hey Corrado,

What does the layout look like? Sounds like you may be seeing some board leakages here. Have you done any guarding on the traces to help reduce this leakage?

Thanks,
Rami

Hi,

I only designer the circuits but not the layout.

Below the layout.

DUT is the Device which measure the voltage at point A or B. The green line is part of circuits excluded by opening manual switch.

So when RS1 and RS2 are mounted I can see a current till 100pA flows through them that affect the voltage measure. 

When RS1 and RS2 are disconnected the current disappear.

My explanation there is a leakage current introduced by TMUX111.

Hi Corrado,

The leakage current is most likely due the layout not incorporating proper guarding as Rami mentioned in his previous post. For applications that require pAs worth of accuracy, many different ICs (including multiplexers) can exhibit extraneous leakage currents if special precautions are not taken for such sensitive nets on your design (such as guarding/shielding). This leakage occurs because the nearby conductors to those traces are at a different potential than those coming from the mux/output to the measurement circuit, thus creating stray/parasitic capacitances along that line that allow extra leakage currents to exist.

Let me know if this makes sense.

Thanks!

Bryan

Hi Corrado,

Following up here. Please let us know if there is something further you would like to discuss on this topic or bring to our attention. Will do our best to work with you here if there is anything else.

Thanks!

Bryan