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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!feed.opticnetworks.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: legg Newsgroups: sci.electronics.design Subject: Re: fast NPN in LT Spice Date: Mon, 10 Jun 2024 17:27:59 -0400 Organization: A noiseless patient Spider Lines: 60 Message-ID: References: <4n2q5jln0sb9oqbfp81jm723tbjf7tol80@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Date: Mon, 10 Jun 2024 23:26:07 +0200 (CEST) Injection-Info: dont-email.me; posting-host="9601cbb5c79b45170877248f59b32bbd"; logging-data="683077"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/K/7BP/8rpGJjB3EZIjRHB" Cancel-Lock: sha1:admM8rEARuFzL7Sthho4VrjVLb0= X-Newsreader: Forte Agent 4.2/32.1118 Bytes: 3585 On Sat, 8 Jun 2024 03:29:11 +1000, Bill Sloman wrote: >On 7/06/2024 11:24 pm, legg wrote: >> On Fri, 7 Jun 2024 14:03:16 +1000, Bill Sloman >> wrote: >> >>> On 7/06/2024 4:05 am, legg wrote: >>>> On Thu, 6 Jun 2024 23:18:12 +1000, Bill Sloman >>>> wrote: >>>> >>>>> On 6/06/2024 1:46 pm, legg wrote: > > > >> That's sort of what I'm talking about. You choose a part, you choose a >> model, you choose a parameter that allows a model to simulate >> performance more accurately. You choose a circuit configuration >> with component values. > >You mostly can't chose an EBIC model because the manufacturers treat >them as "commercial in confidence". > >Gummel-Poon isn't as good, but it's mostly adequate. > >> From the larger spreadsheet, you see models for 'similar devices >> varying widely in performance in a particular circuit configuration. >> >> So what is it, in the model, or in the circuit configuration, that >> allows such a wide variation in performance. What parameter is a >> true predictor? What weakness in the circuit is the wild card? > >Silly question. Gummel-Poon doesn't model inverted bipolar transistor >operation particularly well, but if you want anything else you will have >measure the device parameters for yourself, and nobody here has ever >claimed to have done that. > >> Looking for understanding or beneficial increase in knowledge here. >> Not pushing or pulling the benefits or disadvantages of modeling >> or breadboarding - already have pretty fixed opinions about that. > >Do try to understand what practical circuit designers actually do. > >I've never seen anybody set up a "spreadsheet" of transistor models. > >The process is mostly working out what you can do with what you can get. > >The models aren't perfect, and individual devices aren't identical, so >coping with production variation is part of the job. Some parts are >sorted by the manufacturer after production, which gives you >funny-looking parameter distributions. > >-- >Bill Sloman, Sydney Right, I see Q2 normally inverted. C2 seems unneccessarily loaded. RL