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NNTP-Posting-Date: Mon, 03 Jun 2024 14:18:01 +0000
From: john larkin <jl@650pot.com>
Newsgroups: sci.electronics.design
Subject: Re: fast NPN in LT Spice
Date: Mon, 03 Jun 2024 07:18:01 -0700
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On Mon, 3 Jun 2024 09:58:52 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

>On 6/3/24 00:36, john larkin wrote:
>> There are many NPNs in the standard LT Spice library.
>> 
>> Does anyone know of a fast, RF type, transistor? It's hard to tell
>> from the jillion lines of fine-print parameters.
>> 
>> I want to make a model of the MC10EP89 gate.
>> 
>
>I always used the -now obsolete- BFR92A for such things.
>That's a 5GHz Ft NPN that I used often. It's not in the
>library, I think. Below the model. Mind the line wraps.
>
>Jeroen Belleman
>
>.model BFR92A NPN IS=4.11877E-016 BF=1.02639E+002 NF=9.97275E-001 
>VAF=6.26719E+001 IKF=3.20054E+000 ISE=4.01062E-015 NE=1.57708E+000 
>BR=1.81086E+001 NR=9.96202E-001 VAR=3.36915E+000 IKR=1.28155E+000 
>ISC=2.79905E-016       NC=1.07543E+000 RB=1.00000E+001 IRB=1.00000E-006 
>RBM=1.00000E+001 RE=1.16450E+000 RC=2.32000E+000 EG=1.11000E+000 
>XTI=3.00000E+000 CJE=8.90512E-013 VJE=6.00000E-001 MJE=2.58570E-001 
>TF=1.54973E-011 XTF=3.91402E+001 VTF=2.15279E+000       ITF=2.13776E-001 
>CJC=5.46563E-013 VJC=3.80824E-001 MJC=2.02935E-001

2SC3838K is in the library, and has Ft = 3.5G typically. It's good
enough for what I want to do now. 

This is actually a bit faster than the MC10EP89:

Version 4
SHEET 1 1208 700
WIRE 112 -64 -16 -64
WIRE 272 -64 112 -64
WIRE 400 -64 272 -64
WIRE 576 -64 400 -64
WIRE 576 0 576 -64
WIRE -16 16 -16 -64
WIRE 272 16 272 -64
WIRE 400 96 400 -64
WIRE 272 144 272 96
WIRE 336 144 272 144
WIRE 576 144 576 80
WIRE -192 192 -368 192
WIRE -128 192 -192 192
WIRE -128 224 -128 192
WIRE 112 224 112 -64
WIRE -368 240 -368 192
WIRE 400 256 400 192
WIRE 576 256 400 256
WIRE 624 256 576 256
WIRE 640 256 624 256
WIRE -16 272 -16 96
WIRE 48 272 -16 272
WIRE -368 352 -368 320
WIRE -192 352 -368 352
WIRE -128 352 -128 304
WIRE -128 352 -192 352
WIRE 112 384 112 320
WIRE 400 384 112 384
WIRE 624 384 400 384
WIRE 640 384 624 384
WIRE -368 400 -368 352
WIRE -16 432 -16 272
WIRE 272 432 272 144
WIRE 400 432 400 384
WIRE 576 432 576 256
WIRE -16 560 -16 512
WIRE 272 560 272 512
WIRE 400 560 400 512
WIRE 576 560 576 512
FLAG 576 144 0
FLAG -192 192 A
FLAG -192 352 B
FLAG 624 256 X
FLAG 624 384 Y
FLAG -16 560 0
FLAG 272 560 0
FLAG -368 400 0
FLAG 400 560 0
FLAG 576 560 0
SYMBOL npn 336 96 R0
WINDOW 0 100 21 Left 2
WINDOW 3 71 55 Left 2
SYMATTR InstName Q1
SYMATTR Value 2SC3838K
SYMBOL voltage 576 -16 R0
WINDOW 0 48 40 Left 2
WINDOW 3 54 75 Left 2
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL res 256 0 R0
WINDOW 0 -65 38 Left 2
WINDOW 3 -70 76 Left 2
SYMATTR InstName R2
SYMATTR Value 200
SYMBOL npn 48 224 R0
WINDOW 0 100 21 Left 2
WINDOW 3 71 55 Left 2
SYMATTR InstName Q2
SYMATTR Value 2SC3838K
SYMBOL res -32 0 R0
WINDOW 0 53 46 Left 2
WINDOW 3 48 80 Left 2
SYMATTR InstName R1
SYMATTR Value 200
SYMBOL bi -16 432 R0
WINDOW 0 58 111 Left 2
WINDOW 3 -343 170 Left 2
SYMATTR InstName B1
SYMATTR Value I=4m*( 1 - tanh (200 * ( V(B)-V(A) ) ) )
SYMBOL res -144 208 R0
WINDOW 0 -60 48 Left 2
WINDOW 3 -69 79 Left 2
SYMATTR InstName R5
SYMATTR Value 10K
SYMBOL bi 272 432 R0
WINDOW 0 -91 109 Left 2
WINDOW 3 -100 169 Left 2
SYMATTR InstName B2
SYMATTR Value I=4m*( 1 - tanh (200 * ( V(A)-V(B) ) ) )
SYMBOL voltage -368 224 R0
WINDOW 0 -58 -21 Left 2
WINDOW 3 -94 -80 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(-1 1 1n 500p 500p 2n)
SYMBOL res 384 416 R0
WINDOW 0 53 40 Left 2
WINDOW 3 47 71 Left 2
SYMATTR InstName R3
SYMATTR Value 200
SYMBOL res 560 416 R0
WINDOW 0 49 36 Left 2
WINDOW 3 46 71 Left 2
SYMATTR InstName R4
SYMATTR Value 200
TEXT -288 48 Left 2 !.tran 5n
TEXT 416 232 Left 2 ;1.6v pp
TEXT -296 -40 Left 2 ;MC10EP89
TEXT 136 360 Left 2 ;1.6v pp
TEXT -328 0 Left 2 ;JL  Jun 2  2024