I spent most of the day measuring DC and AC behavior of mid-size (like
60v, 200 mA) schottly diodes. Looks like anything with wirebonds has a good bit of series inductance, enough to cause us trouble. But mini-MELFs are just two metal slugs with the chip soldered between them. I see no inductance with a 30 picosecond TDR step.
ftp://jjlarkin.lmi.net/Mini_Melf_Fixture.JPG
ftp://jjlarkin.lmi.net/NXP_BAS86_TDR.JPG
The TDR is, left to right,
Leadin coax from sampling head
SMA connector transition, at cm 2 or so, small capacitive bump
50 ohm trace, x-acto cut to 50.4 ohms, first try
Diode starts at cm 5. The fall time is pretty much TDR speed, then its capacitance starts to charge.
John