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From: "Helmut Sennewald"
Subject: Re: Q. medium-power RF transistor
Date: Sun, 10 Nov 2002 00:07:40 +0100
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
"Winfield Hill" schrieb im Newsbeitrag
> email@example.com (carltons) wrote...
> > Helmut Sennewald HelmutSennewald@t-online.de wrote:
> >> Winfield Hill schrieb ...
> >>> I'm thinking about making 20 to 30V pulses with a
> >>> 1ns max risetime into a 50-ohm line...
> >>> What's a good low-capacitance transistor to use with
> >>> say Vceo 30V, 500mA capable (h_fe >10 at 500mA) and
> >>> with f_T of at least say 1GHz at Ic 200mA, Vce 15V?
> >> Hello Win,
> >> I would try four cascodes in parallel with BFG135 transistors.
> >> http://www.semiconductors.philips.com/pip/BFG135.html
> >> The product of output capacitance of your transistor(s) and
> >> the load (50Ohm) has to be below the wanted rise time.
> That's a nice transistor, reasonable beta at 100mA, with just
> over 3pF of Ccb+Coe capacitance. I could parallel four with
> a 50-ohm pullup to 25V (each in common-base mode, Vcbo = 25V),
> and still have RC under 1ns. And it looks easy to get.
> But I wonder, where have all the medium-current 25+ volt RF
> transistors gone? All the likely parts I have examined are
> discontinued. For example, an ON Semi MRF3010 or MRF134 RF
> MOSFET (65V, 1A, Coss + Crss < 12pF) would have been nice a
> few years ago. What's the ticket now?
I have looked in my archive about my older contributions
and found the links to the RF-Power Mosfet.
Hopefully I could help you.
---- Original text
Thread: Re: high speed power mosfet models
Take a first look here as Mohi already recommended,
and choose the replacement part. Then go to their part and take
the appropriate SPICE model from Polyfet.
Motorola seems to have only special models for the HF simulation
tools ADS, APLAC and AWR and these are not SPICE based simulators as I
So it looks bad, but what about asking Motorola and tell us what they
Some general info from ST:
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