PIN diode (2023 Update)

DC-wise, it's just a diode. Not too many surprises there.

Jeroen Belleman

Not much likelihood of recognizing one if you stumbled over it either, from lack of marking info.

RL

Thanks for posting this John. I had been looking for something like that for a pulse generator I might want to build one day (after nearly 30 years this day may be coming closer...) and so far I had seen only parts with 1-2 V reverse voltage ability; this one seems to handle way more than I need.

I just found this in my spam folder:

This is hilarious, and attempt to answer their question "why take DC test measurements at all?" when all any RF guy needs is S-parameters.

I can imagine dozens of diode types. This PIN is probably GaAs. I have

+-5 volts available to turn it on and off, but I can imagine having 0/+2.5 from an FPGA, or +-0.8 differential PECL. Its DC curves and tolerances might matter.

You do realize that it's not the PIN diode that makes the pulse, right? A pin diode is merely a switch, and not even a very fast one at that.

Jeroen Belleman

Yeah, the specs shocked me, after struggling to do this with a schottky. The carrier lifetime could be a problem with long pulses.

I love pulse generators. Let me know if I can help.

There are all sorts of cheap fungens and scopes and such, but pulse generators are generally still mediocre and expensive. I want to do one myself some day, a really fast version of our DDG.

Ah, OK! ;-) An RF guy would just apply ten volts through a kOhm and a choke or two, so he doesn't care!

Jeroen Belleman

No. the S-parameter tables give the conditions used for the measurement.

and, for the LTspice fans: spice cannot simulate it.

Gerhard

I have seen step-recovery effects in some PIN diodes, but it's rare and not very useful. I guess the intrinsic region doping profile can accidentally approach an SRD. Better to buy a real one.

On a sunny day (Wed, 20 Oct 2021 09:00:24 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

Was there not a thread here long ago about NPN transistor pulse generators? Something with Vce breakdown?

Barbarians.

The P500 outputs are GaN. SiC rocks for kilovolt stuff. And fast bipolars are all going EOL.

On a sunny day (Wed, 20 Oct 2021 09:38:30 -0700) it happened snipped-for-privacy@highlandsniptechnology.com wrote in snipped-for-privacy@4ax.com:

Dunno about that, you will find those in LNBs for satellite at 10 GHz and more for example. If the economy tanks so to speak, then having a bunch of BJTs and FETS maybe helpful to at least send an S.O.S or do other things. Maybe simple car electronics... better than no car at all because no chips... If people will still know how to drive by then, not all 'auto pilots'. Think I need to order some BC109 ;-) Have some BU208 too... horizontal TV output. Have not tried any SiC yet.

Hey, I know what a diode is and have known how to switch currents using diodes for well over 30 years :-). The problem I hope it will solve is I will not inject too much charge during the switching process, and at 1/4 pF (IIRC) this will be the case, unless there are some unknown to me at this point effects, similar to storage time for bipolars etc.

It's the only suggestion of DC operating point in the entire document. Slightly better than nothing, I guess, generous by RF standards.

This PIN data sheet has a Vf/If curve, absurdly wrong in the RF tradition.

The general tend seems to be high Vf and high reverse leakage.

You already did help, if this is indeed a "normal" diode which can be turned off without conducting back much more than its capacitance would take it will do what I want just fine (take a current from one path into another).

Pins will switch fast signals, but turning the switch on/off is slow, so they can't *make* fast signals.

There are potentially useful GHz-speed IC switches, but the switch times are terrible.

Making fast pulses still requires lots of parts on boards, old-fashioned circuit design.

Always willing to divert to an occasional on-topic discussion.

I honestly have no idea if PIN diodes for RF switching snap. As a rule, they keep conducting for 100ns or so after reversal. I didn't look in detail what happens then. Maybe I'm not curious enough...

I was quite happy to use them as RF switches with tiny parasitics. (I would have used a reed, but the parasitic inductance turned out to be too high in my application.)

Jeroen Belleman