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Reply-To: "Kevin Aylward"
From: "Kevin Aylward"
References: <3D760B64.CC303206@scs.uiuc.edu> <3D763949.4B6D795E@scs.uiuc.edu> <email@example.com> <firstname.lastname@example.org> <3D808AAC.B0C1DDA3@cern.ch> <email@example.com> <3D858448.DAA17B4A@cern.ch> <3D85A1C1.908227B@cern.ch>
Subject: Re: High impedance low noise
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
Date: Mon, 16 Sep 2002 10:59:28 +0100
NNTP-Posting-Date: Mon, 16 Sep 2002 10:59:31 BST
"Jeroen Belleman" wrote in message
> Kevin Aylward wrote:
> > Here is a PSpice model I made many years ago. This might help a bit.
> > .MODEL J2SK162_XN NJF(Beta=161.6m Betatce=-500m Rd=1 Rs=4 Lambda=10m
> > Vto=-380m Vtotc=-2.5m Is=12.66f
> > + Isr=127f N=1 Nr=2 Xti=3 Alpha=10u Vk=100 Cgd=4n M=1.963
> > + Pb=1 Fc=500m Cgs=19.41p Kf=2.5e-003f Af=1)
> > I made it from the data sheet, but it was so long ago I don't recall
> > well I made it.
> Thanks, Kevin. Just one point: Cgd=4n, surely that's not true, is it?
No. This must have been one of those errors that crept in. The number is
too clean let along too huge. Cgd and Cgs are usually about equal. I'd
make it 20pf as a estimate. This number seems reasonable. It is a big
fet in order to get the noise down, but not that big!
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
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