BF998 Silicon N-Channel MOSFET Tetrode
3
Short-channel transistor
with high S/C quality factor
4
For low-noise, gain-controlled
input stages up to 1 GHz
2 1
VPS05178
ESD: Electrostatic discharge sensitive device, observe handling precaution! Type
Marking
BF998
MOs
Pin Configuration 1=S
2=D
3 = G2
Package 4 = G1
SOT143
Maximum Ratings Parameter
Symbol
Drain-source voltage
VDS
12
V
Continuos drain current
ID
30
mA
Gate 1/gate 2 peak source current
±IG1/2SM
10
Total power dissipation, TS 76 °C
Ptot
200
Storage temperature
Tstg
-55 ... 150
Channel temperature
Tch
150
Value
Unit
mW °C
Thermal Resistance Channel - soldering point1)
Rthchs
370
K/W
1For calculation of R thJA please refer to Application Note Thermal Resistance
1
Aug-10-2001
BF998
Electrical Characteristics at TA = 25 °C; unless otherwise specified. Parameter Symbol Values
Unit
min.
typ.
max.
V(BR)DS
12
-
-
Gate 1 source breakdown voltage
±V(BR)G1SS
8
-
12
±IG1S = 10 mA, VG2S = VDS = 0 Gate 2 source breakdown voltage
±V(BR)G2SS
8
-
12
±IG1SS
-
-
50
±IG2SS
-
-
50
IDSS
2
-
18
mA
-VG1S(p)
-
-
2.5
V
-VG2S(p)
-
-
2
DC characteristics Drain-source breakdown voltage
V
ID = 10 µA, VG1S = -4 V, VG2S = -4 V
±IG2S = 10 mA, VG1S = 0 V, VDS = 0 V Gate 1 source leakage current
nA
±VG1S = 5 V, VG2S = VDS = 0 Gate 2 source leakage current ±VG2S = 5 V, VG1S = 0 V, VDS = 0 V Drain current VDS = 8 V, VG1S = 0 , VG2S = 4 V Gate 1 source pinch-off voltage VDS = 8 V, VG2S = 4 , ID = 20 µA Gate 2 source pinch-off voltage VDS = 8 V, VG1S = 0 , ID = 20 µA
2
Aug-10-2001
BF998
Electrical Characteristics Symbol
Parameter
Values
Unit
min.
typ.
max.
gfs
-
24
-
mS
Cg1ss
-
2.1
2.5
pF
Cg2ss
-
1.2
-
Cdg1
-
25
-
fF
Cdss
-
1.1
-
pF
Gps
-
28
-
dB
Gps
-
20
-
F
-
0.6
-
F
-
1
-
40
-
-
AC characteristics Forward transconductance VDS = 8 V, ID = 10 mA, VG2S = 4 V Gate 1 input capacitance VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz Gate 2 input capacitance VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz Feedback capacitance VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz Output capacitance VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 1 MHz Power gain VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 200 MHz Power gain VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 800 MHz Noise figure VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 200 MHz Noise figure VDS = 8 V, ID = 10 mA, VG2S = 4 V, f = 800 MHz
Gps
Gain control range VDS = 8 V, VG2S = 4 ... -2V, f = 800 MHz
3
Aug-10-2001
BF998
Output characteristics ID = f (VDS )
Total power dissipation Ptot = f(TS)
BF 998
25
220 mA
ΙD
180
EHT07333
mA
VG1S = 0.5 V
20
0.4 V
15
0.2 V
P tot
160 140 120 100
0V
10 80 60
-0.2 V
5
40
-0.4 V
20
-0.6 V
0 0
15
30
45
60
75
90 105 120 °C
0
150
0
5
10
V
TS
V DS
Gate 1 forward transconductance
Gate 1 forward transconductance
gfs1 = f (VG1S )
g fs1 = f (V G2S)
30
BF 998
EHT07293
VG2S = 4 V
mS g fs1
15
30
BF 998
EHT07294
mS
VG1S = 0.25 V
g fs1
0V
20
20 -0.25 V
3V
10
10 2V 1V
0
0V -1
0
1
V
0
2
VG1S
-1
0
1
2
3
V
4
VG2S
4
Aug-10-2001
BF998
Gate 1 forward transconductance
Gate 1 input capacitance Cg1ss = f (VG1S)
gfs1 = f (ID ) 30 g fs1
BF 998
EHT07295
mS
VG2S = 4 V
BF 998
2.5 C g1ss
EHT07296
pF 2.0
3V 2V
20
1.5
1.0
10 0.5
1V 0.5 V 0
0V
0.0
5
0
10
15
mA 20
-3
-2
-1
0
ΙD
BF 998
1
VG1S
Gate 2 input capacitance Cg2ss = f (VG2S)
2.0
V
Output capacitance C dss = f (V DS)
EHT07297
3
pF
BF 998
EHT07298
pF
Cg2ss
Cdss
1.5 2
1.0
1
0.5
0.0
-2
-1
0
1
2
3
V
0
4
0
5
10
V
15
V DS
VG2S
5
Aug-10-2001
BF998
Drain current ID = f (VG1S )
Power gain Gps = f (VG2S) f = 200 MHz
BF 998
30
EHT07299 VG2S = 4 V 3V 2V
Ι D mA
30
BF 998
EHT07300
dB Gps
20 10
1V
20
0 -10 10
-20 0V
0
-1
0
1
V
-30 -40
2
-1
0
1
2
3
V G1S
Power gain Gps = f (VG2S)
f = 200 MHz
f = 800 MHZ
F
BF 998
4
VG2S
Noise figure F = f (VG2S )
5
V
EHT07301
30
BF 998
EHT07302
dB
dB
G ps
20
4 10 3
0 -10
2
-20 1 -30 0
0
1
2
3
V
-40
4
V G2S
-1
0
1
2
3
V
4
VG2S
6
Aug-10-2001
BF998
Noise figure F = f (VG2S )
Gate 1 input admittance y11s
f = 800 MHz
(common source)
BF 998
5 F
EHT07303
14
BF 998
EHT07304
mS
dB
b 11s
f = 1200 MHz
12
1100 MHz
4
1000 MHz
10
900 MHz 800 MHz
3
8 700 MHz 600 MHz
6
2
500 MHz 400 MHz
4
300 MHz
1
2
200 MHz 100 MHz
0
1
0
2
3
V
0
4
0
1
2
3
Gate 1 forward transfer admittance y21s
Output admittance y 22s
(common source)
(common-source)
b 21s
BF 998
EHT07305
8
100 MHz
mS
4
g 11s
V G2S
0
mS
b 22s
200 MHz
BF 998
EHT07306
mS
f = 1200 MHz 1100 MHz
-5
300 MHz
6
1000 MHz
400 MHz
900 MHz
500 MHz
-10
800 MHz 600 MHz
700 MHz
4
700 MHz
600 MHz
800 MHz
-15
500 MHz
900 MHz
400 MHz
1000 MHz
-20
2
1100 MHz
300 MHz 200 MHz
f = 1200 MHz
100 MHz
-25 10
15
20
mS
0
25
g 21s
7
0
0.1
0.2
0.3
0.4 mS 0.5 g 22s
Aug-10-2001
