Again! LNA Design with BF998

bf998

hi everyone..

im designing using ADS but i cant locate s2p file...

Does anyone have the s2p file for this transistor?

thanks


ozenk

bf998 preamplifier

it is available from library.

lna bf998

here it is

bf998 lna

thanks for the help...

but i still confuse with this file paramater...

i use in the ampliefier design guide > s-parameter in ADS, it doesnt work well. The noise figure not change when i use different frequency and voltage... my friends said that maybe the typical ofthe S parameter..i confused with that..

oya...

oya.... i design preamplifier in the range 130-140 Mhz in cascade (2 or 3) so i can get high gain...

is it can be modeling with multisim?...


is any example in multisim? or ADS?.....

i have been search in this forum but i can solve my problem...



thanks for the help...

bf998 preamp

If you check the NF file you find that there are only two NF points, so you need a simulation software able to interpolate the results for different frequencies.

With voltage the NF anyway will not the change, because in the S-param/Noise file is specified only at one bias point.

bf998 biasing

yaps...

i think, that the reason why it doesnt work with other frequency...

but what you (vfone) mean about a simulation software...is you mean BF998 can not be simulate by ADS...because the paramater is specified at one bias point so whatever i configured the bias circuit, i unable to get dynamic Noise Figure (change with different frequency)....

bf998 spice

I mean a linear simulation is using an s2p file, (where parameters are specified at only one bias point) and whatever DC bias you change in the schematic, the noise will not change.

To get NF vs bias change, you need a nonlinear simulation, using a nonlinear model (not s2p).

bf998 spice model

im undertsand what you mean...

so im must use non linear model...i get it the file from NXP semiconductor....

it is just like in other thread in LNA ..


* BF998 SPICE MODEL OCTOBER 1993 PHILIPS SEMICONDUCTORS
* ENVELOPE SOT143 (R)
* 1.: SOURCE; 2.: DRAIN; 3.: GATE 2; 4.: GATE 1;
.SUBCKT BF998 1 2 3 4
L10 1 10 L=0.12N
L20 2 20 L=0.12N
L30 3 30 L=0.12N
L40 4 40 L=0.12N
L11 10 11 L=1.20N
L21 20 21 L=1.20N
L31 30 31 L=1.20N
L41 40 41 L=1.20N
C13 10 30 C=0.085P
C14 10 40 C=0.085P
C23 20 30 C=0.085P
C24 20 40 C=0.005P
D11 42 11 ZENER
D12 42 41 ZENER
D21 32 11 ZENER
D22 32 31 ZENER
RS 10 12 R=100
MOS1 61 41 11 12 GATE1 L=1.1E-6 W=1150E-6
MOS2 21 31 61 12 GATE2 L=2.0E-6 W=1150E-6

.MODEL ZENER D BV=10 CJO=1.2E-12 RS=10

.MODEL GATE1
+ NMOS LEVEL=3 UO=600 VTO=-0.250 NFS=300E9 TOX=42E-9
+ NSUB=3E15 VMAX=140E3 RS=2.0 RD=2.0 XJ=200E-9 THETA=0.11
+ ETA=0.06 KAPPA=2 LD=0.1E-6
+ CGSO=0.3E-9 CGDO=0.3E-9 CBD=0.5E-12 CBS=0.5E-12

.MODEL GATE2
+ NMOS LEVEL=3 UO=600 VTO=-0.250 NFS=300E9 TOX=42E-9
+ NSUB=3E15 VMAX=100E3 RS=2.0 RD=2.0 XJ=200E-9 THETA=0.11
+ ETA=0.06 KAPPA=2 LD=0.1E-6
+ CGSO=0.3E-9 CGDO=0.3E-9 CBD=0.5E-12 CBS=0.5E-12

.ENDS BF998


so i must use PSPice software to get simulation

or im can still ADS but replace the file parameter..?

in other thread it said "You can use the spice model to to the HB simulation and get the conversion gain"...


mm...

i will try to use it...

thanks...

bf998 s parameters

Guess it's a popular device and a lot of folks want the s-parameter file

so here's the s2p file


! SIEMENS Small Signal Semiconductors
! BF998
! Si Dual Gate MOSFET Tetrode in SOT143
! VDS = 8 V VG2S = 4 V ID = 5 mA
! Common Source S-Parameters: May 1988
# GHz S MA R 50
! f S11 S21 S12 S22
! GHz MAG ANG MAG ANG MAG ANG MAG ANG
0.050 0.9992 -2.9 1.818 175.3 0.0006 89.2 0.9962 -1.7
0.060 0.9991 -3.5 1.820 174.4 0.0006 94.0 0.9960 -2.0
0.070 0.9984 -4.1 1.819 173.4 0.0006 92.8 0.9965 -2.3
0.080 0.9983 -4.7 1.819 172.4 0.0009 83.6 0.9962 -2.6
0.090 0.9981 -5.3 1.820 171.4 0.0009 85.1 0.9960 -3.0
0.100 0.9975 -5.8 1.821 170.4 0.0010 86.0 0.9962 -3.3
0.150 0.9942 -8.8 1.818 165.4 0.0015 84.7 0.9951 -5.0
0.200 0.9901 -11.7 1.812 160.4 0.0019 82.2 0.9950 -6.7
0.250 0.9854 -14.6 1.804 155.4 0.0025 79.8 0.9937 -8.3
0.300 0.9793 -17.4 1.789 150.5 0.0028 78.0 0.9921 -10.0
0.400 0.9643 -23.1 1.753 140.8 0.0035 70.3 0.9891 -13.2
0.500 0.9471 -28.5 1.710 131.3 0.0043 68.8 0.9865 -16.5
0.600 0.9280 -33.9 1.668 122.1 0.0046 64.9 0.9828 -19.7
0.700 0.9083 -39.3 1.622 113.0 0.0050 65.6 0.9798 -23.0
0.800 0.8854 -44.5 1.569 104.2 0.0056 61.5 0.9749 -26.2
0.900 0.8616 -49.6 1.519 95.6 0.0054 57.2 0.9712 -29.3
1.000 0.8384 -54.5 1.474 87.2 0.0051 57.8 0.9691 -32.4
1.200 0.7866 -64.7 1.386 70.2 0.0048 65.6 0.9606 -39.1
1.400 0.7312 -74.4 1.280 53.7 0.0040 68.6 0.9504 -46.0
1.500 0.7076 -78.7 1.234 46.1 0.0038 84.6 0.9482 -49.3
1.600 0.6833 -82.8 1.191 38.4 0.0039 93.0 0.9469 -52.6
1.800 0.6411 -91.4 1.128 23.2 0.0044 116.6 0.9456 -59.3
2.000 0.5980 -100.7 1.074 7.2 0.0053 133.5 0.9423 -66.8
!
! SIEMENS AG Semiconductor Group, Munich

Cheers,
Mike