X-Received: by 2002:a37:cc81:: with SMTP id n1-v6mr4074470qkl.44.1538654425318; Thu, 04 Oct 2018 05:00:25 -0700 (PDT) X-Received: by 2002:a37:6203:: with SMTP id w3-v6mr78297qkb.6.1538654425138; Thu, 04 Oct 2018 05:00:25 -0700 (PDT) Path: csiph.com!xmission!news.snarked.org!border2.nntp.dca1.giganews.com!nntp.giganews.com!m93-v6no668649qte.0!news-out.google.com!i36-v6ni2213qti.0!nntp.google.com!m93-v6no668642qte.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: sci.electronics.design Date: Thu, 4 Oct 2018 05:00:24 -0700 (PDT) In-Reply-To: <3j2brdlncd0dsn48vkv3e8cfu96el9k9at@4ax.com> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=172.58.225.124; posting-account=vPfM1woAAABXtZGvJzP3XEqhyiqNwdWX NNTP-Posting-Host: 172.58.225.124 References: <389c8897-eca4-4dcd-843a-f3406f3d23d7@googlegroups.com> <3j2brdlncd0dsn48vkv3e8cfu96el9k9at@4ax.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <2ac37dbb-2c85-4351-94de-8d8bb2e4e7a7@googlegroups.com> Subject: Re: really fast buffers From: pcdhobbs@gmail.com Injection-Date: Thu, 04 Oct 2018 12:00:25 +0000 Content-Type: text/plain; charset="UTF-8" Lines: 17 Xref: csiph.com sci.electronics.design:518319 >>https://octopart.com/search?q=BFP650&oq=BFP650&start=0 >That would work, as a couple or few emitter followers to fan out my >incoming signal. It has decent beta at, say, 50 mA or even 100 mA >(driving something like 5 volts into 50 ohms). >The Vbe offset would be more predictable than the turn-on of a phemt. Their low drain impedances make pHEMTs very disappointing as followers, unless you bootstrap the drain. The late lamented ATF38148 could have a gain of 0.5 as a follower. >I'll be timing edges to picoseconds so I don't want unpredictable offsets. You'll need a base resistor to keep it from oscillating. Don't let anybody hang a cable on it. Cheers Phil Hobbs