Help with interview question

[IA52]

Help with interview question - Design test jig for digital circuit

Hello, I have this question for an interview, i'm fully prepared to tell said employer that I have never heard of this before etc, i'm not sure if i'm even supposed to have heard of it. A series of random testing questions, I have done the software one and one about 4 wire resistance testing method.

This one though, its hard to find information on

1:You are tasked to design an interface jig for a high speed digital UUT. What considerations must be made in the design of the jig and its wiring?

I assume the interface jig simply must not interfere with the UUT but how does it interfere? The wiring must be what? Low EMI? Shielded? have decoupling capacitors somewhere?

Thanks in advance :thumbsup:

 

[barry]

A pretty vague question, I understand your confusion. But you can say that the wiring must match the impedance(s) of the UUT. Without knowing more about what you are testing, it's a pretty stupid question. Maybe ask him what color he would like the jig to be.

 

[IA52]

The test jig must not interfere with the UUT as little as possible by reducing EMI. The wires and UUT must have matched impedance. Possibly shield the wires to reduce EMI, have decoupling capacitors in the Jig. The goal of the jig is to affect as little as possible in the UUT while testing its functionality.

Ideally you would be able to test the UUT as if the jig was not there at all.
Other than not interfering with the digital circuit, the Jig must be capable of picking up high speed oscillations to ensure accurate measurement of the UUT.

This is what I said so far, been working on the other questions. At the very least...am I not wrong in my general statements? I never heard of jig before 2 days ago :/

 

[asdf44]

Yes it's vague. I take it they're getting at general signal integrity issues while transmitting high speed signals over a wire.

So I think the things mentioned so far cover a lot of it. Impedance, shielding, proper termination, wire choice, connector choice etc.