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VHF 20DB GAIN TRANSISTOR

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rjcamatos
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Sir,
I simulate an RF 100MHz Cascaded 3 Transistors acting as Low Pass Filter to 20KHz (audible sinal) to extract FM modulated signal and it work as expected on simulation, but on reality the the transistor that i try don't amplify the 100MHz signal as oposit it decreases the gain (im using 2sc2498 npn).
So my question is what transistors can i use to have gain about 20Db (if not asking to mutch) on a 88MHz to 108MHz signal? LTSpice model is an requirement.
I know i should have an RF mixer than demodulate it, but i hould like to amplify the mentioned frequencies.

Best Regards.
 

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TonyStark
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***

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zsugori
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****

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rjcamatos
rjcamatos picture

BC635 as well and have shop near me.
please inform what parameter is refered to as gain operation frequency?
This is described as Ft 200MHz, but in gain graphic it is mention 100MHz high gain.
​How should i search for high frequency transistors?

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zsugori
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****

1
2SC535
BF...
SS....
nem a boltban kell keresni

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rjcamatos
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I read that the current gain can be calculated using the formula:
Ft/RF=CG

Ft = Transistor transiton frequency
RF = Signal to amplify
CG = Current Gain
If like that for 100 Gain of 100Mhz require 10GHz Ft
 

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rjcamatos
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MCH4015 - NPN 10GHZ FT

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rjcamatos
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Yap, tested on LTSPICE NPN SS9014 RESULTING IN AN HIGH GAIN AT 100MHZ.

.model ss9014 npn is=2.87599e-14 bf=377.5 vaf=123 ikf=1.1841 ise=4.7863f ne=1.5 br=4.79 var=11.29 ikr=0.275423 isc=1.44544e-14 nc=1.5 rb=200 irb=1e-5 rbm=10 re=0.56 rc=5 cje=1.7205e-11 vje=0.6905907 mje=0.3193434 tf=5.89463e-10 cjc=6.2956p vjc=0.4164212 mjc=0.2559546 xcjc=0.451391 xtb=1.8881 eg=1.2415 xti=3 fc=0.5 Vceo=45 Icrating=0.1 mfg=Fairchild

 

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