Semiconductor Group 1 04.96
Silicon N Channel MOSFET Tetrode BF 998
Features
●Short-channel transistor
with high S/C quality factor
●For low-noise, gain-controlled
input stages up to 1 GHz
Maximum Ratings
Type Marking Package1)
Pin Configuration
BF 998 Q62702-F1129MO SOT-143
1 2 3 4
S D G2G1
Ordering Code
(tape and reel)
Parameter Symbol Values Unit
Drain-source voltage VDS 12 V
Thermal Resistance
Junction - soldering point Rth JS < 370 K/W
Total power dissipation, TS < 76 ˚C Ptot 200 mW
Storage temperature range Tstg – 55 … + 150 ˚C
Gate 1/gate 2 peak source current ±IG1/2SM 10
Channel temperature Tch 150
mADrain current ID30
1) For detailed information see chapter Package Outlines.
BF 998
Semiconductor Group 2
Electrical Characteristics
at TA = 25 ˚C, unless otherwise specified.
UnitValues
Parameter Symbol
min. typ. max.
VDrain-source breakdown voltage
I
D = 10 µA, – VG1S = – VG2S = 4 V V(BR) DS 12 – –
nAGate 1-source leakage current
±VG1S = 5 V, VG2S = VDS = 0 ± IG1SS ––50
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 = VDS = 0 ± V(BR) G2SS 8–12
Gate 2-source leakage current
±VG2S = 5 V, VG1S = VDS = 0 ± IG2SS ––50
mADrain current
VDS = 8 V, VG1S = 0, VG2S = 4 V IDSS 2–18
VGate 1-source pinch-off voltage
VDS = 8 V, VG2S = 4 V, ID= 20 µA– VG1S(p) – – 2.5
Gate 2-source pinch-off voltage
VDS = 8 V, VG1S = 0, ID= 20 µA– VG2S(p) ––2
DC Characteristics
BF 998
Semiconductor Group 3
Electrical Characteristics
at TA = 25 ˚C, unless otherwise specified.
Control range
(test circuit 2)
VDS = 8 V, VG2S = 4 … – 2 V
f = 800 MHz
∆Gps 40 – –
dBNoise figure
(test circuit 1)
VDS = 8 V, ID = 10 mA, f = 200 MHz,
GG = 2 mS, GL = 0.5 mS, VG2S = 4 V
F– 0.6 –
Noise figure
(test circuit 2)
VDS = 8 V, ID = 10 mA, f = 800 MHz,
GG = 3.3 mS, GL = 1 mS, VG2S = 4 V
F–1–
UnitValues
mS
Parameter
Forward transconductance
VDS = 8 V, ID = 10 mA, VG2S = 4 V
f = 1 kHz
Symbol
gfs
min.
–
typ.
24
max.
–
pFGate 1 input capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V
f = 1 MHz
Cg1ss – 2.1 2.5
Gate 2 input capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V
f = 1 MHz
Cg2ss – 1.2 –
fFReverse transfer capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V
f = 1 MHz
Cdg1 –25–
pFOutput capacitance
VDS = 8 V, ID = 10 mA, VG2S = 4 V
f = 1 MHz
Cdss – 1.05 –
dBPower gain
(test circuit 1)
VDS = 8 V, ID = 10 mA, f = 200 MHz,
GG = 2 mS, GL = 0.5 mS, VG2S = 4 V
Gps –28–
Power gain
(test circuit 2)
VDS = 8 V, ID = 10 mA, f = 800 MHz,
GG = 3.3 mS, GL = 1 mS, VG2S = 4 V
Gps –20–
AC Characteristics
BF 998
Semiconductor Group 4
Total power dissipation Ptot = f (TA)
Gate 1 forward transconductance
gfs1 = f (VG1S)
VDS = 8 V, IDSS = 10 mA, f = 1 kHz
Output characteristics ID = f (VDS)
VG2S = 4 V
Gate 1 forward transconductance
gfs1 = f (VG2S)
VDS = 8 V, IDSS = 10 mA, f = 1 kHz
BF 998
Semiconductor Group 5
Gate 1 forward transconductance
gfs1 = f (ID)
VDS = 8 V, IDSS = 10 mA, f = 1 kHz
Gate 2 input capacitance Cg2ss = f (VG2S)
VG1S = 0 V, VDS = 8 V
IDSS = 10 mA, f = 1 MHz
Gate 1 input capacitance Cg1ss = f (VG1S)
VG2S = 4 V, VDS = 8 V, IDSS = 10 mA,
f = 1 MHz
Output capacitance Cdss = f (VDS)
VG1S = 0 V, VG2S = 4 V
IDSS = 10 mA, f = 1 MHz
BF 998
Semiconductor Group 6
Drain current ID = f (VG1S)
VDS = 8 V
Noise figure F = f (VG2S)
VDS = 8 V, VG1S = 0, IDSS = 10 mA,
f = 200 MHz (see test circuit 1)
Power gain Gps = f (VG2S)
VDS = 8 V, VG1S = 0, IDSS = 10 mA,
f = 200 MHz (see test circuit 1)
Power gain Gps = f (VG2S)
VDS = 8 V, VG1S = 0, IDSS = 10 mA,
f= 800 MHz (see test circuit 2)
BF 998
Semiconductor Group 7
Noise figure F = f (VG2S)
VDS = 8 V, VG1S = 0, IDSS = 10 mA,
f = 800 MHz (see test circuit 2)
Gate 1 forward transfer admittance y21s
VDS = 8 V, VG2S = 4 V, VG1S = 0
IDSS = 10 mA (common-source)
Gate 1 input admittance y11s
VDS = 8 V, VG2S = 4 V, VG1S = 0,
IDSS = 10 mA (common-source)
Output admittance y22s
VDS = 8 V, VG2S = 4 V, VG1S = 0
IDSS = 10 mA (common-source)
BF 998
Semiconductor Group 8
Test circuit 1 for power gain and noise figure
f = 200 MHz, GG = 2 mS, GL = 0.5 mS
Test circuit 2 for power gain and noise figure
f = 800 MHz, GG = 3.3 mS, GL = 1 mS
