Rectify 500MHz Small Signal
in [Design]
|
From: John Larkin on 28 Sep 2009 21:42 On Mon, 28 Sep 2009 17:46:39 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: > >[...] > >> But I meant active switching when I was referring to a TD. A TD would >> *generate* a fast step from an arbitrarily slow drive. >> > >Forgot to mention, I was also never able to lay my hand on a tunnel >diode. The hobbyist books had schematics with them in there but that was >all bogus, just like UJTs were. Unobtanium. Can you buy a TD in large >qties at a reasonable price somewhere? I mean, not the $100 ones. Not any more. I used to buy them from Allied for a few bucks, when I was a kid. More recently, I was prowling through some dusty bins at HalTed and found one full of TDs. They didn't know what they were... just wires with bumps. 10 cents each. RCA made TDs with peak point currents over 100 amps, but I don't think they found any good uses for them. The only germanium tunneling parts still made in any volume are RF detector back diodes. GPD bought the old GE td process, which was insane, but they don't seem to make them any more. Maybe somebody else got it. http://www.gpd-ir.com/products.htm John
From: John Larkin on 28 Sep 2009 21:42 On Mon, 28 Sep 2009 17:55:40 -0700, Mycelium <mycelium(a)thematrixattheendofthemushroomstem.org> wrote: >On Mon, 28 Sep 2009 17:46:39 -0700, Joerg <invalid(a)invalid.invalid> >wrote: > >>John Larkin wrote: >> >>[...] >> >>> But I meant active switching when I was referring to a TD. A TD would >>> *generate* a fast step from an arbitrarily slow drive. >>> >> >>Forgot to mention, I was also never able to lay my hand on a tunnel >>diode. The hobbyist books had schematics with them in there but that was >>all bogus, just like UJTs were. Unobtanium. Can you buy a TD in large >>qties at a reasonable price somewhere? I mean, not the $100 ones. > > > Old radios (transceivers). Old Tek scopes and plugins. John
From: Rene Tschaggelar on 29 Sep 2009 05:22 Jim Thompson wrote: > Anyone have clever ideas for rectifying a 500MHz sine wave, amplitude > say 50mV to 500mV peak-to-peak? > > Half wave is OK. > > 1mV accuracy is needed :-( > > Process is X-Fab XB06. > > Thanks! > > ...Jim Thompson There are zero-bias diodes available up to at least Xband (10GHz). They have a sensitivity of in the order of -55dBm I recently got some for 30 bucks each. Rene
From: Jan Panteltje on 29 Sep 2009 07:11 On a sunny day (Mon, 28 Sep 2009 17:46:39 -0700) it happened Joerg <invalid(a)invalid.invalid> wrote in <7id3ngF30fqppU1(a)mid.individual.net>: >John Larkin wrote: > >[...] > >> But I meant active switching when I was referring to a TD. A TD would >> *generate* a fast step from an arbitrarily slow drive. >> > >Forgot to mention, I was also never able to lay my hand on a tunnel >diode. The hobbyist books had schematics with them in there but that was >all bogus, just like UJTs were. UJTs were very available. I have used them for H and V oscillator in a vidicon camera I designed in 1968. Also used those in thyristor drive circuits, in large quantities, same time. Tunnel diodes were also available, but have not used them. Worked with some equipment that had them in it. In some of the Ampex quadruplex videotape recorders the FM modulator was a tunnel diode. UJTs are cool.
From: John Fields on 29 Sep 2009 08:08
On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever ><OneBigLever(a)InfiniteSeries.Org> wrote: > >>On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell" >>><mike.terrell(a)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. --- http://en.wikipedia.org/wiki/PIN_diode#RF_and_Microwave_Switches --- >There was a single-TD circuit that was an RF amp, a local oscillator, >a mixer, and an IF amp. One TD and a couple of passives would make an >FM transmitter. --- news:9ut3c51te70akq93hddmq4084us66ui4d8(a)4ax.com JF |