J
Joerg
Guest
John Larkin wrote:
and the higher the RF current, the longer its carrier lifetime must be.
I found PIN diodes to be great and most of all cheap variable
attenuators as well as switched. Designed in tons of them.
either couldn't have one or it was outlandishly expensive. Guess
avalanching is the only game in town and if you want avalanche-rated
then a bone-simple BJT can easily shoot up to twenty bucks.
--
Regards, Joerg
http://www.analogconsultants.com/
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Got to watch the carrier lifetime. The lower the bottom of your spectrumOn Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:
John Fields wrote:
On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever
OneBigLever@InfiniteSeries.Org> wrote:
On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
John Larkin wrote:
There's the slideback technique: drive a comparator with RF on one
side, DC feedback on the other. Tease the DC appropriately.
I once made a slideback sampling oscilloscope, using tunnel diodes, as
my EE senior project. I won an award and had to attend a dreadful IEEE
chapter banquet and repeat it to a bunch of old-fart power engineers
who didn't understand a word I said. I described the slideback
sampling scope in this ng some years back and a certain party loved
the idea so much he later decided that he'd invented it himself.
http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html
TDs are insanely expensive nowadays, ballpark $100. I used to get them
for a couple bucks from Allied. The fabrication process is insane, and
nobody ever modernized it.
There are some more modern planar germanium back diodes, essentially
low Ip tunnel diodes, but they're RF detectors, useless for switching.
Pity, I used to like tunnel diodes.
http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf
John
Try PiN diodes then.
For what? Certainly not switching, amplifying, oscillating, detection,
or mixing.
---
Re. switching, From:
http://en.wikipedia.org/wiki/PIN_diode
"Under zero or reverse bias, a PIN diode has a low capacitance. The low
capacitance will not pass much of an RF signal. Under a forward bias of
1 mA, a typical PIN diode will have an RF resistance of about 1 ohm,
making it a good RF conductor. Consequently, the PIN diode makes a good
RF switch."
---
Good, but not fast. PIN diodes specialize in having a lot of stored
charge, so that the signal current can be quite a bit larger than the DC
current without causing excessive distortion.
Cheers
Phil Hobbs
PINs stop behaving like PINs at low frequencies, too. So they don't
make useful wideband switches.
and the higher the RF current, the longer its carrier lifetime must be.
I found PIN diodes to be great and most of all cheap variable
attenuators as well as switched. Designed in tons of them.
I've drooled over SRDs all my life and every time I wanted to buy one IBut I meant active switching when I was referring to a TD. A TD would
*generate* a fast step from an arbitrarily slow drive.
either couldn't have one or it was outlandishly expensive. Guess
avalanching is the only game in town and if you want avalanche-rated
then a bone-simple BJT can easily shoot up to twenty bucks.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.