Rectify 500MHz Small Signal
in [Design]
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From: Joerg on 29 Sep 2009 12:25 John Larkin wrote: > On Mon, 28 Sep 2009 17:43:22 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> 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. > > SRDs aren't hard to get. MA/Com has distributor parts, under a buck. > M-Pulse and Metelics are good about samples. If you want a few, send > me a SASE. > > Oh, here it is... > > 229-1769 DIO SRD 30V SOT23 150PS MA44769 1PF > > MA44769-287 PENSTOCK > > Price 58 cents in small quantities. > > They also have MA44767-287, 600 ps risetime, a little easier to drive > because it stores more charge. > > These make nice edge generators and frequency multipliers. I have a > rubidium clock that generates the 6.3846826128 GHz frequency from a 10 > MHz rock with an absurdly small number of cheap parts. > Thanks, John! That's a decent price. And thanks for the SASE offer, but maybe I'll combine that with a beer at Zeitgeist when I get down there :-) As a kid I grew up in Europe and back then such exotic parts were very hard to find over there, even at hamfests. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 29 Sep 2009 12:34 Jan Panteltje wrote: > 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. Well, yeah, but you probably lived in the Netherlands as a kid. You guys had dump handelaars and all sorts of electronics places. UJTs were unobtanium in Germany. Once in a while we'd mount a car and head over the border. But since I was a kid back then and didn't have my own car I'd have to hitch a ride. We usually split the cost for gas and then it was affordable for everyone, but you needed a whole day. Later I lived in Zuid Limburg and with a stiff bicycle ride you could haul stuff home from the surplus dealer in Margraten. Wrecked many baggage racks that way, plus some chains, axles and so on. And found out the hard way that bicycle brakes don't work so good with 50 pounds of stuff on the back. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 29 Sep 2009 12:47 On Tue, 29 Sep 2009 09:25:15 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Mon, 28 Sep 2009 17:43:22 -0700, Joerg <invalid(a)invalid.invalid> >> wrote: >> >>> 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. >> >> SRDs aren't hard to get. MA/Com has distributor parts, under a buck. >> M-Pulse and Metelics are good about samples. If you want a few, send >> me a SASE. >> >> Oh, here it is... >> >> 229-1769 DIO SRD 30V SOT23 150PS MA44769 1PF >> >> MA44769-287 PENSTOCK >> >> Price 58 cents in small quantities. >> >> They also have MA44767-287, 600 ps risetime, a little easier to drive >> because it stores more charge. >> >> These make nice edge generators and frequency multipliers. I have a >> rubidium clock that generates the 6.3846826128 GHz frequency from a 10 >> MHz rock with an absurdly small number of cheap parts. >> > >Thanks, John! That's a decent price. And thanks for the SASE offer, but >maybe I'll combine that with a beer at Zeitgeist when I get down there :-) Well, drop in. We have a zillion exotic parts in stock. And the quality of Z's burgers has improved radically lately. Only biker bar I know of with Chimay on tap. > >As a kid I grew up in Europe and back then such exotic parts were very >hard to find over there, even at hamfests. We were lucky. Tons of exotic surplus gear, lots of old teevees, Allied and Lafayette and Fair Radio Sales mail-order available to anyone, local distributors for over-the-counter transistors and 10-turn pots and such... the counter guys gave me more parts than I ever paid for. I made a deal with my parents to dump my allowance in favor of a revolving credit account with Allied, so I could just order stuff. I made spending money fixing radios and TVs. John
From: John Larkin on 29 Sep 2009 13:13 On Tue, 29 Sep 2009 11:22:32 +0200, Rene Tschaggelar <none(a)none.net> wrote: >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 Try Skyworks. Similar parts for under a buck. John
From: Jan Panteltje on 29 Sep 2009 13:25
On a sunny day (Tue, 29 Sep 2009 09:34:08 -0700) it happened Joerg <invalid(a)invalid.invalid> wrote in <7ier86F30e1vkU1(a)mid.individual.net>: >> UJTs are cool. > > >Well, yeah, but you probably lived in the Netherlands as a kid. You guys >had dump handelaars and all sorts of electronics places. UJTs were >unobtanium in Germany. Once in a while we'd mount a car and head over >the border. But since I was a kid back then and didn't have my own car >I'd have to hitch a ride. We usually split the cost for gas and then it >was affordable for everyone, but you needed a whole day. > >Later I lived in Zuid Limburg and with a stiff bicycle ride you could >haul stuff home from the surplus dealer in Margraten. Wrecked many >baggage racks that way, plus some chains, axles and so on. And found out >the hard way that bicycle brakes don't work so good with 50 pounds of >stuff on the back. Still widely available, I used the 2N2646: http://nl.farnell.com/unijunction-transistors-ujt |