100GHz transistors
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From: Paul Keinanen on 6 Feb 2010 02:27 On Fri, 05 Feb 2010 23:28:40 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: > >Even more interesting is the maximum speed it can do >I am not talking about 100GHz. What exactly does cut off frequency mean for a FET ? In bipolars the current gain drops below 1 at fT but you still can get some usable power gain in common base configuration at higher frequencies. Before the invention of real microwave tubes (such as klystrons, magnetrons TWTs etc.) much of the UHF/microwave amplification was done my grounded grid tubes.
From: Jan Panteltje on 6 Feb 2010 06:49 On a sunny day (Sat, 06 Feb 2010 09:27:51 +0200) it happened Paul Keinanen <keinanen(a)sci.fi> wrote in <b06qm55b5hrq6cthlcb0usdppkbsahustp(a)4ax.com>: >On Fri, 05 Feb 2010 23:28:40 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >> >>Even more interesting is the maximum speed it can do >>I am not talking about 100GHz. > >What exactly does cut off frequency mean for a FET ? > >In bipolars the current gain drops below 1 at fT but you still can get >some usable power gain in common base configuration at higher >frequencies. > >Before the invention of real microwave tubes (such as klystrons, >magnetrons TWTs etc.) much of the UHF/microwave amplification was done >my grounded grid tubes. Yes, but apart from power gain, say linear applications, an area where this would have applications is in switching circuits. Think 100 GHz up to 5 THz (if my info is right) processors. That would change a few thing.
From: Dirk Bruere at NeoPax on 6 Feb 2010 07:29 Bill Sloman wrote: > On Feb 6, 12:28 am, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote: >> On a sunny day (Fri, 5 Feb 2010 15:00:53 -0800 (PST)) it happened Bill Sloman >> <bill.slo...(a)ieee.org> wrote in >> <16ba972d-76b2-4dbf-a0f3-4e7307fd9...(a)21g2000yqj.googlegroups.com>: >> >>> On Feb 5, 8:41 pm, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote: >>>> 100GHz transistors >>>> On graphene >>>> http://www.sciencemag.org/cgi/content/abstract/327/5966/662 >>> The interesting thing about that abstract isn't the 100GHz - all sorts >>> of handmade graphene transistors seem to be able to do that well - but >>> the phrase "Transistors were fabricated on epitaxial graphene >>> synthesized on the silicon face of a silicon carbide wafer" which >>> suggests that these particular transistors might be susceptible to >>> mass-production, which is what we have all been waiting for. >>> -- >>> Bill Sloman, Nijmegen >> Even more interesting is the maximum speed it can do >> I am not talking about 100GHz. > > Then what on earth are you talking about? And why isn't the 100GHz > figure - which you chose to emphasise by using it to name of this > thread - a useful indicator of the speed of the part? Because scaling it downwards and otherwise tweaking it will likely push it to 1THz, which is what the project is aiming at. -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.theconsensus.org/ - A UK political party http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: Dirk Bruere at NeoPax on 6 Feb 2010 07:30 Jan Panteltje wrote: > 100GHz transistors > On graphene > http://www.sciencemag.org/cgi/content/abstract/327/5966/662 Looks like a smooth transition to graphene will occur within the decade. Moore's Law marches on. -- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.theconsensus.org/ - A UK political party http://www.blogtalkradio.com/onetribe - Occult Talk Show
From: John Devereux on 7 Feb 2010 10:30 Joerg <invalid(a)invalid.invalid> writes: > a7yvm109gf5d1(a)netzero.com wrote: >> On Feb 5, 6:28 pm, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote: >>> On a sunny day (Fri, 5 Feb 2010 15:00:53 -0800 (PST)) it happened Bill Sloman >>> <bill.slo...(a)ieee.org> wrote in >>> <16ba972d-76b2-4dbf-a0f3-4e7307fd9...(a)21g2000yqj.googlegroups.com>: >>> >>>> On Feb 5, 8:41 pm, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote: >>>>> 100GHz transistors >>>>> On graphene >>>>> http://www.sciencemag.org/cgi/content/abstract/327/5966/662 >>>> The interesting thing about that abstract isn't the 100GHz - all sorts >>>> of handmade graphene transistors seem to be able to do that well - but >>>> the phrase "Transistors were fabricated on epitaxial graphene >>>> synthesized on the silicon face of a silicon carbide wafer" which >>>> suggests that these particular transistors might be susceptible to >>>> mass-production, which is what we have all been waiting for. >>>> -- >>>> Bill Sloman, Nijmegen >>> Even more interesting is the maximum speed it can do >>> I am not talking about 100GHz. >> >> One day after the first 100GHz CPU hits stores, all the software dorks >> of the planet will invent such abstract, surreal and wasteful new ways >> to "program" that you won't be able to tell that CPU from a 1GHz PIII. >> Picture a 1TB mouse driver that needs a few dozen virtual machines ... >> Because you can. > > > But we as users are often not much better than bloatware > programmers. I often receive drawings as printable docs. Typically a > huge file, even one-sheeters often wouldn't have fit onto a floppy > disk back in the old days. Yet one can create the same sort of info in > a 50k PNG file ... There is a company I deal with (I informally administer the computers for them). Someone there designed a new format for quotations. Basically a single-page Excel file with some thumbnails of the products. Thanks to the wonders of MS Office (and ignorance) the document ended up ~200MB. For each quote. They were generating a few GB per day for something that could have been typed up on a few pages of A4. I only found out when "the internet got slow"... Then there's another guy there who likes to regularly dump 5GB of solidworks modelling data onto the server. > In 1989 my whole biz book-keeping database set fit onto one 1.44MB > disk, including the SW to run it. My 2009 set would still fit on such > a disk, except that the "modern" SW version needs several times more > program storage space than my whole hard drive had back then. Same here, for a couple of years after we started all my PCB design files & source code went on one floppy. -- John Devereux
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