Rectify 500MHz Small Signal
in [Design]
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From: Rene Tschaggelar on 29 Sep 2009 15:59 John Larkin wrote: > 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 > Thanks John, we then took some M/A-Com parts. It was to be mounted into a waveguide in the DO119 case. I'll have a look at skyworks for next time. They deliver through BFI Optilas and possibly digikey. Rene
From: Jim Thompson on 29 Sep 2009 16:09 On Tue, 29 Sep 2009 12:56:53 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Phil Hobbs wrote: >> Joerg wrote: >>> Phil Hobbs wrote: >>>> Jan Panteltje wrote: >>>>> 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 >>>> >>>> I like PUTs for things like laser interlocks. Unlike ICs, I know >>>> exactly how they'll behave in fault conditions, which matters a lot. >>>> Relays are good too. >>>> >>> >>> Thanks. AFAICT the 2646 has long since been obsoleted, maybe still >>> considered by boutique mfgs. When I was young I was always told "We >>> can order it but that'll really cost ya". I didn't know you could >>> still get the 6027 although the fact that it was never migrated to SMT >>> doesn't bode well for its future. >>> >>> Personally I have never seen a design that contained a UJT, this >>> technology may have played chicken and egg for too long. >>> >> >> For my purposes the two-BJT SCR works fine too. Doesn't have to be >> fast, just very reliable and predictable. >> > >If I need a crowbar or something to that effect I usually take a regular >SCR, a TL431, a transistor and some resistors. You can make that go off >at rather precise levels. Impressed a client quite a bit who was used to >the regular sloppy crowbars. I told them mine would trigger between 3.6V >and 3.7V. "Really?" ... "Yeah". It triggered at precisely 3.65V :-) From the late '70's onward I've probably used as many TL431's as OpAmps... the world's most "peppy" NPN ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Coming soon to the elementary school in your neighborhood... I pledge allegiance to Dear Leader Barack Hussein Obama and to the community organization for which he stands: one nation under ACORN, unchallengeable, with wealth redistribution and climate change for all.
From: Joerg on 29 Sep 2009 16:19 Jim Thompson wrote: > On Tue, 29 Sep 2009 12:56:53 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> Phil Hobbs wrote: >>> Joerg wrote: >>>> Phil Hobbs wrote: >>>>> Jan Panteltje wrote: >>>>>> 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 >>>>> I like PUTs for things like laser interlocks. Unlike ICs, I know >>>>> exactly how they'll behave in fault conditions, which matters a lot. >>>>> Relays are good too. >>>>> >>>> Thanks. AFAICT the 2646 has long since been obsoleted, maybe still >>>> considered by boutique mfgs. When I was young I was always told "We >>>> can order it but that'll really cost ya". I didn't know you could >>>> still get the 6027 although the fact that it was never migrated to SMT >>>> doesn't bode well for its future. >>>> >>>> Personally I have never seen a design that contained a UJT, this >>>> technology may have played chicken and egg for too long. >>>> >>> For my purposes the two-BJT SCR works fine too. Doesn't have to be >>> fast, just very reliable and predictable. >>> >> If I need a crowbar or something to that effect I usually take a regular >> SCR, a TL431, a transistor and some resistors. You can make that go off >> at rather precise levels. Impressed a client quite a bit who was used to >> the regular sloppy crowbars. I told them mine would trigger between 3.6V >> and 3.7V. "Really?" ... "Yeah". It triggered at precisely 3.65V :-) > > From the late '70's onward I've probably used as many TL431's as > OpAmps... the world's most "peppy" NPN ;-) > Same here. I always wanted one in PNP flavor. IIRC there was (is?) a National part but it was expensive so I always sprung for another NPN behind the TL431. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Jan Panteltje on 29 Sep 2009 17:29 On a sunny day (Tue, 29 Sep 2009 13:29:48 -0400) it happened Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote in <lvqdnVZytI2N2V_XnZ2dnUVZ_rOdnZ2d(a)supernews.com>: >I like PUTs for things like laser interlocks. Unlike ICs, I know >exactly how they'll behave in fault conditions, which matters a lot. >Relays are good too. > >Cheers > >Phil Hobbs I have never used PUTs, think I have some in the box though. I liked the UJTs so much because if you made a RC oscillator with those, then the frequency would be independent of the supply voltage. This because the intrinsic standoff ratio is fixed at say about 0.6. Later the 555 timer appeared, with f also independent of supply voltage... I kept using UJTs. They were easy to sync too.
From: John Larkin on 29 Sep 2009 17:54
On Tue, 29 Sep 2009 12:53:36 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Tue, 29 Sep 2009 13:34:14 -0400, Phil Hobbs >> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >> >>> John Larkin wrote: >>>> 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 >>>> >>> Still not as good as now. I just bought an excellent-condition HP 8568B >>> spectrum analyzer for $900. About 2 cents on the dollar. So far this >>> year I've bought test equipment that would have cost way over $100000 >>> new, for probably $4k altogether. Amazing. >>> >>> Cheers >>> >>> Phil Hobbs >> >> And I'm looking at, theoretically, a quarter million dollars worth of >> sampling heads over there on my shelf. This is an amazing time to >> start a niche business, or even an exotic hobby. >> > >Is there anything available at reasonable cost that does zippy sampling >without needing a Goliath of a scope attached to it? Not really. The 5000 and 7000 series scopes had sampling plugins - I have a bunch, and they're dirt cheap now - but they were pretty bad compared to the superb 11801-series stuff. There are some little USB samplers, but they're very expensive. Pumping scope is good for you. John |