> Noise figure is something that can be assured
> over a wafer a little easier than things like
> Idss, Vp and g_subm (gm), and these last two
> parameters are something that can be probed on-wafer
> whereas NF (on a discrete part such as this)
> cannot owing to the fact that there are no pads/RF
> structures to bring in the 'stripline RF probes'
> and perform this high-frequency measurement at
> frequency (like 1 GHz).
>
> To assure a wafer is at a particular NF value testing
> is done on specialized transisitor test-structures
> that possess the necessary RF pads in test reticles
> that allow just a few easy, quick RF measurements
> (RF measurements take more time per part, require
> specialized RF probes versus the simpler "probe
> cards" used for DC tests and also requires a Noise
> Figure Measuring Test Set, plus DC supplies to bias
> the part during testing).

Ahh... All becomes clear.  I know very little of IC manufacture.  Just a
little bit about some parts.  I was extrapolating that based on the
placement in the circuit, but you are, I have no doubt quite correct.

> Since the gain of the device can be tracked via so-called
> "DC on-wafer tests" (that don't require specialized
> conditions like on-wafer RF testing does) the
> gm (transconductance), Vp (gate pinch-off voltage) and
> Idss (drain current with zero gate voltage) parameters
> can be measured and logged -
>
> - tests which also assure device functionality - I'd say
> that those marks were for gain-binning.
>
> But, I could be wrong. I don't know what this manufacturer
> was doing - and I was just extrapolating based on what our
> foundry did (our product was GaAs devices, including
> discretes and MMIC's (Microwave Monolithic Integrated
> Circuits - almost RF SOIC's in some cases!).

I doubt, at this stage, that you're wrong.  Everything you mentioned makes
sense to me.  (I've used a NF meter before, but not with much success, and
I'm not really a RF tech, but I'm having to do the job for now)

--Brendan

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