De-embedded S-parameters

Are most transistor s-parameter files de-embedded to the edge of the casing (i.e. including the leads) or to the edge of the leads (not including the leads).

I have a transistor from sirenza (SPF-2086TK) that the datasheet says "de-embedded to device pins" and I am trying to determine if they mean the edge of the device leads or not. I am using high dielectric substrate so the leads on the input and output can add an additional phase change of 27 degrees.

Any knowledge would be appreciated.
-Brandon

If it's a power transistor package (source flange with flat gate and drain leads) then the de-embedding is to the package, meaning the solder pad and lead has been removed from the measurement.

More than likely this part is to the edge of the lead however they don't tell what substrate was used so you'll have to make some assumptions on how much shunt capacitance to add to compensate for your increased Er. You can probably assume:

1) The width of the example pad is close to 50 ohms.

2) They used a board material with Er from 3.5 to 4.5; lower or higher is typically not used for fixturing, rather antenna or small, distributed circuits.

If you are using this at 6 GHz and need that much phase accuracy then you'll need to measure it yourself using the desired board material and pad geometry. Now I'll plug Modelithics:


http://www.modelithics.com/products/3.htm

Hi,

transitor S parameters are usually de-embedded to the transistor capsule (leads are excluded). This applyies to most of the test fixtures used in measurements.

flyhigh