DATA SHEET
Product specification
Supersedes data of 1995 Apr 25
File under Discrete Semiconductors, SC07
1997 Sep 05
DISCRETE SEMICONDUCTORS
BF998WR
N-channel dual-gate MOS-FET
1997 Sep 05
2
Philips Semiconductors
Product specification
N-channel dual-gate MOS-FET
BF998WR
FEATURES
High forward transfer admittance
Short channel transistor with high forward transfer
admittance to input capacitance ratio
Low noise gain controlled amplifier up to 1 GHz.
APPLICATIONS
VHF and UHF applications with 12 V supply voltage,
such as television tuners and professional
communications equipment.
DESCRIPTION
Depletion type field-effect transistor in a plastic
microminiature SOT343R package with source and
substrate interconnected. The transistor is protected
against excessive input voltage surges by integrated
back-to-back diodes between gates and source.
CAUTION
The device is supplied in an antistatic package. The
gate-source input must be protected against static
discharge during transport or handling.
PINNING
PIN
SYMBOL
DESCRIPTION
1
s, b
source
2
d
drain
3
g
2
gate 2
4
g
1
gate 1
Fig.1 Simplified outline (SOT343R) and symbol.
Marking code: MB.
MAM198
Top view
2
1
3
4
s,b
d
g
1
g
2
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
V
DS
drain-source voltage
-
-
12
V
I
D
drain current
-
-
30
mA
P
tot
total power dissipation
-
-
300
mW
T
j
operating junction temperature
-
-
150
C
y
fs
forward transfer admittance
-
24
-
mS
C
ig1-s
input capacitance at gate 1
-
2.1
-
pF
C
rs
reverse transfer capacitance
f = 1 MHz
-
25
-
fF
F
noise figure
f = 800 MHz
-
1
-
dB
1997 Sep 05
3
Philips Semiconductors
Product specification
N-channel dual-gate MOS-FET
BF998WR
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
Note
1. Device mounted on a printed-circuit board.
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
V
DS
drain-source voltage
-
12
V
I
D
drain current
-
30
mA
I
G1
gate 1 current
-
10
mA
I
G2
gate 2 current
-
10
mA
P
tot
total power dissipation
up to T
amb
= 45
C; see Fig.2; note 1
-
300
mW
T
stg
storage temperature
-
65
+150
C
T
j
operating junction temperature
-
+150
C
Fig.2 Power derating curve.
handbook, halfpage
0
50
100
200
0
MLD154
150
400
200
300
100
Ptot
(mW)
T ( C)
amb
o
1997 Sep 05
4
Philips Semiconductors
Product specification
N-channel dual-gate MOS-FET
BF998WR
THERMAL CHARACTERISTICS
Notes
1. Device mounted on a printed-circuit board.
2. T
s
is the temperature at the soldering point of the source lead.
STATIC CHARACTERISTICS
T
j
= 25
C; unless otherwise specified.
DYNAMIC CHARACTERISTICS
Common source; T
amb
= 25
C; V
G2-S
= 4 V; I
D
= 10 mA; V
DS
= 8 V; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
VALUE
UNIT
R
th j-a
thermal resistance from junction to ambient
note 1
350
K/W
R
th j-s
thermal resistance from junction to soldering point
note 2; T
s
= 90
C
200
K/W
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
V
(BR)G1-SS
gate 1-source breakdown voltage
V
G2-S
= V
DS
= 0; I
G1-S
= 10 mA
6
20
V
V
(BR)G2-SS
gate 2-source breakdown voltage
V
G1-S
= V
DS
= 0; I
G2-S
= 10 mA
6
20
V
V
(P)G1-S
gate 1-source cut-off voltage
V
G2-S
= 4 V; V
DS
= 8 V; I
D
= 20
A
-
-
2.5
V
V
(P)G2-S
gate 2-source cut-off voltage
V
G1-S
= 0; V
DS
= 8 V; I
D
= 20
A
-
-
2
V
I
DSS
drain-source current
V
G2-S
= 4 V; V
DS
= 8 V; V
G1-S
= 0
2
18
mA
I
G1-SS
gate 1 cut-off current
V
G2-S
= V
DS
= 0; V
G1-S
= 5 V
-
50
nA
I
G2-SS
gate 2 cut-off current
V
G1-S
= V
DS
= 0; V
G2-S
= 5 V
-
50
nA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
y
fs
forward transfer admittance
pulsed; T
j
= 25
C
22
25
-
mS
C
ig1-s
input capacitance at gate 1
f = 1 MHz
-
2.1
2.5
pF
C
ig2-s
input capacitance at gate 2
f = 1 MHz
-
1.2
-
pF
C
os
drain-source capacitance
f = 1 MHz
-
1.05
-
pF
C
rs
reverse transfer capacitance f = 1 MHz
-
25
-
fF
F
noise figure
f = 200 MHz; G
S
= 2 mS; B
S
= B
Sopt
-
0.6
-
dB
f = 800 MHz; G
S
= 3.3 mS; B
S
= B
Sopt
-
1
-
dB
1997 Sep 05
5
Philips Semiconductors
Product specification
N-channel dual-gate MOS-FET
BF998WR
Fig.3 Transfer characteristics; typical values.
V
DS
= 8 V.
T
amb
= 25
C.
0
24
16
8
0
1
1
MGC471
I D
(mA)
V (V)
G1 S
V = 4 V
3 V
2 V
1 V
0 V
G2 S
Fig.4 Output characteristics; typical values.
V
G2-S
= 4 V.
T
amb
= 25
C.
0
24
16
8
0
2
10
MGC470
4
6
8
I D
(mA)
V (V)
DS
0.4 V
0.3 V
0.2 V
0.1 V
-
0.1 V
0 V
V =
G1 S
-
0.2 V
-
0.3 V
-
0.4 V
-
0.5 V
V
DS
= 8 V; V
G2
= 4 V; T
amb
= 25
C.
Fig.5
Drain current as a function of gate 1 voltage;
typical values.
-
1600
400
24
0
8
16
MGC472
-
1200
-
800
-
400
0
max
typ
min
ID
(mS)
V (mV)
G1
Fig.6
Forward transfer admittance as a function
of drain current; typical values.
V
DS
= 8 V; T
amb
= 25
C.
0
20
30
0
6
MGC473
12
18
24
4
8
12
16
y fs
(mS)
I (mA)
D
V = 0 V
G2
-
S
0.5 V
4 V
3 V
2 V
1 V
PDF 
ZIP