BF998W
Aug-10-20011
Silicon N-Channel MOSFET Tetrode
Short-channel transistor
with high S/C quality factor
For low-noise, gain-controlled
input stages up to 1 GHz
VPS05605
4
2
1
3
ESD: Electrostatic discharge sensitive device, observe handling precaution!
Type Marking Pin Configuration Package
BF998W MRs 1=D 2=S 3=G1 4=G2 SOT343
Maximum Ratings
Parameter ValueSymbol Unit
Drain-source voltage VDS 12 V
Continuos drain current ID30 mA
Gate 1/gate 2 peak source current ±IG1/2SM 10
Total power dissipation, TS = 94 °C Ptot 200 mW
Storage temperature Tstg 55 ... 150 °C
Channel temperature Tch 150
Thermal Resistance
Channel - soldering point1) Rthchs
280 K/W
1For calculation of RthJA please refer to Application Note Thermal Resistance
BF998W
Aug-10-20012
Electrical Characteristics at TA = 25 °C; unless otherwise specified.
Parameter Symbol Values Unit
min. typ. max.
DC characteristics
Drain-source breakdown voltage
ID = 10 µA, VG1S = -4 V, VG2S = -4 V V(BR)DS 12 - - V
Gate 1 source breakdown voltage
±IG1S = 10 mA, VG2S = VDS = 0 ±V(BR)G1SS 8 - 12
Gate 2 source breakdown voltage
±IG2S = 10 mA, VG1S = 0 V, VDS = 0 V ±V(BR)G2SS 8 - 12
Gate 1 source leakage current
±VG1S = 8 V, VG2S = VDS = 0 ±IG1SS - - 50 nA
Gate 2 source leakage current
±VG2S = 8 V, VG1S = 0 V, VDS = 0 V ±IG2SS - - 50
Drain current
VDS = 8 V, VG1S = 0 , VG2S = 4 V IDSS 2 - 18 mA
Gate 1 source pinch-off voltage
VDS = 8 V, VG2S = 0 , ID = 20 µA -VG1S(p) - - 2.5 V
Gate 2 source pinch-off voltage
VDS = 8 V, VG1S = 0 , ID = 20 µA -VG2S(p) - - 2
BF998W
Aug-10-20013
Electrical Characteristics
Parameter ValuesSymbol Unit
max.min. typ.
AC characteristics
24 --
gfs
Forward transconductance
VDS = 8 V, ID = 10 mA, VG2S = 4 V mS
2.5
Cg1ss
Gate 1 input capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz pF2.1-
-
Cg2ss -Gate 2 input capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz 1.2
Feedback capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz fF-25
Cdg1 -
Output capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz - pF
Cdss 1.1-
-Power gain
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 200 MHz -
Gps 28 dB
--
Gps
Power gain
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 800 MHz 20
-Noise figure
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 200 MHz -
F0.6
--
F
Noise figure
VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 800 MHz 1
-Gain control range
VDS = 8 V, VG2S = 4 ... -2V, f = 800 MHz 40
Gps -
BF998W
Aug-10-20014
Output characteristics ID = f (VDS)
0
0
EHT07333BF 998
Ι
D
DS
V
VG1S = 0.5
5
10
15
20
mA
25
510V15
0.4 V
-0.2 V
V
0.2 V
0 V
-0.4 V
-0.6 V
Total power dissipation Ptot = f(TS)
0 15 30 45 60 75 90 105 120 °C 150
TS
0
20
40
60
80
100
120
140
160
180
mA
220
Ptot
Gate 1 forward transconductance
gfs1 = f (VG2S)
-1
0
EHT07294BF 998
g
fs1
G2S
V
V
G1S
= 0.25
0
-0.25
0123V4
10
20
mS
30
V
V
V
Gate 1 forward transconductance
gfs1 = f (VG1S)
-1
0
EHT07293BF 998
g
fs1
G1S
V
= 4
G2S
V
01V2
10
20
mS
30
3
V
V
V2
1V
V0
BF998W
Aug-10-20015
Gate 1 forward transconductance
gfs1 = f (ID)
0
0
EHT07295BF 998
gfs1
D
Ι
1
G2S
V
10
20
mS
30
51015mA20
3
= 4
0.5
0
2
V
V
V
V
V
V
Gate 1 input capacitance Cg1ss = f (VG1S)
-3
0.0
EHT07296BF 998
C
g1ss
G1S
V
-2 -1 0 V 1
0.5
1.0
1.5
2.0
pF
2.5
Output capacitance Cdss = f (VDS)
0
0
EHT07298BF 998
C
dss
DS
V
510 15V
1
2
pF
3
Gate 2 input capacitance Cg2ss = f (VG2S)
-2
0.0
EHT07297BF 998
C
g2ss
G2S
V
-1 0 1 2 3 V 4
0.5
1.0
1.5
2.0
pF
BF998W
Aug-10-20016
Drain current ID = f (VG1S)
-1
0
EHT07299BF 998
G1S
V
Ι
D
10
20
30
mA
= 4 V
01V2
V
G2S
3V
V2
1V
V0
Power gain Gps = f (VG2S)
f = 200 MHz
-1
-40
EHT07300BF 998
G
ps
G2S
V
0123V4
-30
-20
-10
0
10
20
30
dB
Noise figure F = f (VG2S)
f = 200 MHz
0
0
EHT07301BF 998
F
G2S
V
4
5
1
2
3
dB
123V4
Power gain Gps = f (VG2S)
f = 800 MHZ
-1
-40
EHT07302BF 998
G
ps
G2S
V
0123V4
-30
-20
-10
0
10
20
30
dB
BF998W
Aug-10-20017
Gate 1 input admittance y11s
(common source)
0
0
EHT07304BF 998
b
11s
g
11s
100
200
300
400
500
600
1100
= 1200
f
123mS4
2
4
6
8
10
12
mS
14
700
800
1000
900
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
Noise figure F = f (VG2S)
f = 800 MHz
0
0
EHT07303BF 998
F
G2S
V
4
5
1
2
3
dB
123V4
Output admittance y22s
(common-source)
0
0
EHT07306BF 998
b
22s
g
0.1 0.2 0.3 0.4
mS
0.5
22s
100
200
300
400
500
800
1000
= 1200
f
2
4
6
mS
8
600
700
900
1100
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
Gate 1 forward transfer admittance y21s
(common source)
10
-25
EHT07305BF 998
b
21s
g
21s
= 1200
f
1100
1000
900
800
15 20 mS 25
-20
-15
-10
-5
mS
0
700
600
500
400
300
200
100
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
