Rectify 500MHz Small Signal
in [Design]
|
From: John Fields on 28 Sep 2009 19:48 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. --- 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." --- >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. --- Got a link? --- >The beefier td's would make a voltage step with a 22 picosecond rise >time... in 1964. --- Got a link?
From: Phil Hobbs on 28 Sep 2009 20:05 John Fields wrote: > 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. > > --- > 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 -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: John Larkin on 28 Sep 2009 20:28 On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >John Fields wrote: >> 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. >> >> --- >> 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. But I meant active switching when I was referring to a TD. A TD would *generate* a fast step from an arbitrarily slow drive. John
From: Phil Hobbs on 28 Sep 2009 20:38 John Larkin wrote: > On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> John Fields wrote: >>> 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. >>> --- >>> 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. > > But I meant active switching when I was referring to a TD. A TD would > *generate* a fast step from an arbitrarily slow drive. > > John > Sure. TDs are neat. I have a bunch of low-current ones, but they have some totally absurd capacitance and so aren't that fast. The really quick ones have peak currents of something like 50-100 mA. Kind of like a turbocharged rock crusher. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Joerg on 28 Sep 2009 20:43
John Larkin wrote: > On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> John Fields wrote: >>> 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. >>> --- >>> 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. > Got to watch the carrier lifetime. The lower the bottom of your spectrum 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. > But I meant active switching when I was referring to a TD. A TD would > *generate* a fast step from an arbitrarily slow drive. > I've drooled over SRDs all my life and every time I wanted to buy one I 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. |