Forums

PIN diode

Started by Unknown October 19, 2021
On Wed, 20 Oct 2021 17:59:06 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

>On 2021-10-20 17:42, Dimiter_Popoff wrote: >> On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>> >>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>> this one is shocking: >>> >>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>> >>> 2 ohms on, 0.14 pF off. >>> >>> And that's packaged. Chip and beam-lead parts are even better. >>> >>> Of course, in the long-honored RF tradition, there are no DC specs. No >>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>> 1 volt might happen. >>> >>> >>> >> >> 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. > >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
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. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
On a sunny day (Wed, 20 Oct 2021 09:00:24 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<2ve0ng59aqcm1o44fgmc9kfp6rped1aaae@4ax.com>:

>On Wed, 20 Oct 2021 18:42:53 +0300, Dimiter_Popoff <dp@tgi-sci.com> >wrote: > >>On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>> >>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>> this one is shocking: >>> >>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>> >>> 2 ohms on, 0.14 pF off. >>> >>> And that's packaged. Chip and beam-lead parts are even better. >>> >>> Of course, in the long-honored RF tradition, there are no DC specs. No >>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>> 1 volt might happen. >>> >>> >>> >> >>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. > >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. > >http://www.highlandtechnology.com/DSS/P500DS.shtml
Was there not a thread here long ago about NPN transistor pulse generators? Something with Vce breakdown?
On Wed, 20 Oct 2021 18:03:20 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

>On 2021-10-20 17:46, jlarkin@highlandsniptechnology.com wrote: >> On Wed, 20 Oct 2021 08:29:17 +0200, Jeroen Belleman >> <jeroen@nospam.please> wrote: >> >>> On 2021-10-20 04:20, jlarkin@highlandsniptechnology.com wrote: >>>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>>> >>>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>>> this one is shocking: >>>> >>>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>>> >>>> 2 ohms on, 0.14 pF off. >>>> >>>> And that's packaged. Chip and beam-lead parts are even better. >>>> >>>> Of course, in the long-honored RF tradition, there are no DC specs. No >>>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>>> 1 volt might happen. >>> >>> DC-wise, it's just a diode. Not too many surprises there. >>> >>> Jeroen Belleman >> >> I just found this in my spam folder: >> >> https://rfmwblog.com/2021/10/18/why-are-dc-specifications-included-on-rf-device-data-sheets/?utm_source=RFMWSource-Monthly&utm_campaign=20211017-Source&utm_medium=email&utm_term=blog-dc-specs&utm_content=blog >> >> 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. > >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
Barbarians. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
On Wed, 20 Oct 2021 16:19:02 GMT, Jan Panteltje
<pNaonStpealmtje@yahoo.com> wrote:

>On a sunny day (Wed, 20 Oct 2021 09:00:24 -0700) it happened >jlarkin@highlandsniptechnology.com wrote in ><2ve0ng59aqcm1o44fgmc9kfp6rped1aaae@4ax.com>: > >>On Wed, 20 Oct 2021 18:42:53 +0300, Dimiter_Popoff <dp@tgi-sci.com> >>wrote: >> >>>On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>>> >>>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>>> this one is shocking: >>>> >>>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>>> >>>> 2 ohms on, 0.14 pF off. >>>> >>>> And that's packaged. Chip and beam-lead parts are even better. >>>> >>>> Of course, in the long-honored RF tradition, there are no DC specs. No >>>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>>> 1 volt might happen. >>>> >>>> >>>> >>> >>>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. >> >>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. >> >>http://www.highlandtechnology.com/DSS/P500DS.shtml > >Was there not a thread here long ago about NPN transistor pulse generators? >Something with Vce breakdown?
The P500 outputs are GaN. SiC rocks for kilovolt stuff. And fast bipolars are all going EOL. -- Father Brown's figure remained quite dark and still; but in that instant he had lost his head. His head was always most valuable when he had lost it.
On a sunny day (Wed, 20 Oct 2021 09:38:30 -0700) it happened
jlarkin@highlandsniptechnology.com wrote in
<1ch0nghafkfedg43auu6vrbqt0c9mmcckr@4ax.com>:

>On Wed, 20 Oct 2021 16:19:02 GMT, Jan Panteltje ><pNaonStpealmtje@yahoo.com> wrote: >>Was there not a thread here long ago about NPN transistor pulse generators? >>Something with Vce breakdown? > >The P500 outputs are GaN. SiC rocks for kilovolt stuff. And fast >bipolars are all going EOL.
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.
On 10/20/2021 18:59, Jeroen Belleman wrote:
> On 2021-10-20 17:42, Dimiter_Popoff wrote: >> On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>> >>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>> this one is shocking: >>> >>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>> >>> 2 ohms on, 0.14 pF off. >>> >>> And that's packaged. Chip and beam-lead parts are even better. >>> >>> Of course, in the long-honored RF tradition, there are no DC specs. No >>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>> 1 volt might happen. >>> >>> >>> >> >> 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. > > 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
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.
On Wed, 20 Oct 2021 18:05:10 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

>Am 20.10.21 um 17:59 schrieb Jeroen Belleman: >> On 2021-10-20 17:42, Dimiter_Popoff wrote: >>> On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>>> >>>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>>> this one is shocking: >>>> >>>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>>> >>>> 2 ohms on, 0.14 pF off. >>>> >>>> And that's packaged. Chip and beam-lead parts are even better. >>>> >>>> Of course, in the long-honored RF tradition, there are no DC specs. No >>>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>>> 1 volt might happen. > >No. the S-parameter tables give the conditions used for the measurement.
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. https://www.digikey.com/en/products/detail/infineon-technologies/BA895E6327/12109715 The general tend seems to be high Vf and high reverse leakage. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
On 10/20/2021 19:00, jlarkin@highlandsniptechnology.com wrote:
> On Wed, 20 Oct 2021 18:42:53 +0300, Dimiter_Popoff <dp@tgi-sci.com> > wrote: > >> On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>> >>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>> this one is shocking: >>> >>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>> >>> 2 ohms on, 0.14 pF off. >>> >>> And that's packaged. Chip and beam-lead parts are even better. >>> >>> Of course, in the long-honored RF tradition, there are no DC specs. No >>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>> 1 volt might happen. >>> >>> >>> >> >> 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. > > 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. > > http://www.highlandtechnology.com/DSS/P500DS.shtml > > > >
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).
On Wed, 20 Oct 2021 20:51:32 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:

>On 10/20/2021 18:59, Jeroen Belleman wrote: >> On 2021-10-20 17:42, Dimiter_Popoff wrote: >>> On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>>> >>>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>>> this one is shocking: >>>> >>>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>>> >>>> 2 ohms on, 0.14 pF off. >>>> >>>> And that's packaged. Chip and beam-lead parts are even better. >>>> >>>> Of course, in the long-honored RF tradition, there are no DC specs. No >>>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>>> 1 volt might happen. >>>> >>>> >>>> >>> >>> 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. >> >> 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 > >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.
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. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
On Wed, 20 Oct 2021 20:54:52 +0300, Dimiter_Popoff <dp@tgi-sci.com>
wrote:

>On 10/20/2021 19:00, jlarkin@highlandsniptechnology.com wrote: >> On Wed, 20 Oct 2021 18:42:53 +0300, Dimiter_Popoff <dp@tgi-sci.com> >> wrote: >> >>> On 10/20/2021 5:20, jlarkin@highlandsniptechnology.com wrote: >>>> I want to inject a 100 ps test pulse into a 50 ohm transmission line, >>>> tee-wise, sometimes, from a 25 ohm source. So I need a series switch. >>>> >>>> I'd never paid much attention to PIN diodes... they are RF stuff. But >>>> this one is shocking: >>>> >>>> https://www.mouser.com/datasheet/2/249/MADP_008120_12790T-1921620.pdf >>>> >>>> 2 ohms on, 0.14 pF off. >>>> >>>> And that's packaged. Chip and beam-lead parts are even better. >>>> >>>> Of course, in the long-honored RF tradition, there are no DC specs. No >>>> hint of the forward conduction curve. A tiny note suggests that 10 mA, >>>> 1 volt might happen. >>>> >>>> >>>> >>> >>> 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. >> >> 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. >> >> http://www.highlandtechnology.com/DSS/P500DS.shtml >> >> >> >> > >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).
Always willing to divert to an occasional on-topic discussion. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon