BF998/BF998R
N-Channel Dual Gate MOS-Fieldeffect Tetrode,
Depletion Mode
Electrostatic sensitive device.
Observe precautions for handling.
Applications
Input- and mixer stages in UHF- and VHF-tuner
Features
D
D
D
D
D
Integrated gate protection diodes
Low noise figure
Low feedback capacitance
High cross modulation performance
Low input capacitance
D
High AGC-range
D
High gain
D
Available with reverse pin configuration (BF 998 R)
on request
2
1
1
2
94 9279
13 579
94 9278
95 10831
3
4
4
3
BF998 Marking: MO
Plastic case (SOT 143)
1 = Source; 2 = Drain; 3 = Gate 2; 4 = Gate 1
BF998R Marking: MOR
Plastic case (SOT 143R)
1 = Source; 2 = Drain; 3 = Gate 2; 4 = Gate 1
Absolute Maximum Ratings
Parameters
Drain source voltage
Drain current
Gate 1/gate 2-source peak current
Gate 1/gate 2-source voltage
Total power dissipation
Channel temperature
Storage temperature range
T
amb
≤
60
°C
Symbol
V
DS
I
D
±I
G1/G2SM
±V
G1S/G2S
P
tot
T
Ch
T
stg
Value
12
30
10
7
200
150
–65 ... +150
Unit
V
mA
mA
V
mW
°C
°C
Maximum Thermal Resistance
Parameters
Channel ambient on glass fibre printed board
25 x 20 x 1.5 mm
3
plated with 35
m
m Cu
Symbol
R
thChA
Value
450
Unit
K/W
TELEFUNKEN Semiconductors
Rev. A2, 07-Mar-97
1 (8)
BF998/BF998R
Electrical DC Characteristics
T
amb
= 25
_
C
Parameters / Test Conditions
Drain-source breakdown voltage
I
D
= 10
m
A,–V
G1S
= –V
G2S
= 4 V
Gate 1-source breakdown voltage
±I
G1S
= 10 mA, V
G2S
= V
DS
= 0
Gate 2-source breakdown voltage
±I
G2S
= 10 mA, V
G1S
= V
DS
= 0
Gate 1-source leakage current
±V
G1S
= 5 V, V
G2S
= V
DS
= 0
Gate 2-source leakage current
±V
G2S
= 5 V, V
G1S
= V
DS
= 0
Drain current
V
DS
= 8 V, V
G1S
= 0, V
G2S
= 4 V
Type
Symbol
V(
BR)DS
±V
(BR)G1SS
±V
(BR)G2SS
±I
G1SS
±I
G2SS
BF 998 /
BF 998 R
BF 998 A /
BF 998 RA
BF 998 B /
BF 998 RB
I
DSS
I
DSS
I
DSS
–V
G1S(OFF)
–V
G2S(OFF)
4
4
9.5
1.0
0.6
Min
12
8
8
14
14
50
50
Typ
Max
Unit
V
V
V
nA
nA
18
10.5
18
2.0
1.0
mA
mA
mA
V
V
Gate 1-source cut-off voltage
V
DS
= 8 V, V
G2S
= 4 V, I
D
= 20
m
A
Gate 2-source cut-off voltage
V
DS
= 8 V, V
G1S
= 0, I
D
= 20
m
A
Electrical AC Characteristics
V
DS
= 8 V, I
D
= 10 mA, V
G2S
= 4 V, f = 1 MHz, T
amb
= 25
°C
Parameters / Test Conditions
Forward transadmittance
Gate 1 input capacitance
Gate 2 input capacitance
V
G1S
= 0, V
G2S
= 4 V
Feedback capacitance
Output capacitance
Power gain
g
S
= 2 mS, g
L
= 0.5 mS, f = 200 MHz
g
S
= 3.3 mS, g
L
= 1 mS, f = 800 MHz
AGC range
V
G2S
= 4 V to –2 V, f = 800 MHz
Noise figure
g
S
= 2 mS, g
L
= 0.5 mS, f = 200 MHz
g
S
= 3.3 mS, g
L
= 1 mS, f = 800 MHz
Symbol
y
21s
C
issg1
C
issg2
C
rss
C
oss
G
ps
G
ps
∆G
ps
F
F
Min
21
Typ
24
2.1
1.1
25
1.05
28
20
Max
2.5
Unit
mS
pF
pF
fF
pF
dB
dB
dB
1.0
1.5
dB
dB
16.5
40
2 (8)
TELEFUNKEN Semiconductors
Rev. A2, 07-Mar-97
BF998/BF998R
Common Source S-Parameters
V
G2S
= 4 V, Z
0
= 50
W
S
11
V
DS
/V
I
D
/mA
f/MHz
LOG
MAG
dB
–0.03
–0.15
–0.34
–0.57
–0.83
–1.10
–1.35
–1.62
–1.84
–2.09
–2.33
–2.52
–2.72
–0.04
–0.15
–0.38
–0.62
–0.91
–1.19
–1.45
–1.74
–2.01
–2.27
–2.52
–2.73
–2.94
–0.04
–0.16
–0.39
–0.64
–0.93
–1.22
–1.50
–1.80
–2.06
–2.32
–2.59
–2.78
–3.00
ANG
deg
–7.2
–14.1
–20.9
–27.4
–33.6
–39.3
–45.0
–50.1
–55.6
–60
.6
–65.4
–70.2
–74.9
–7.6
–14.8
–21.9
–28.6
–35.0
–41.0
–46.6
–52.0
–57.5
–62.5
–67.2
–72.0
–76.6
–7.6
–14.9
–22.1
–28.9
–35.3
–41.5
–47.1
–52.6
–58.0
–62.9
–67.7
–72.4
–77.0
LOG
MAG
dB
5.71
5.51
5.20
4.84
4.39
3.98
3.57
3.16
2.80
2.43
2.11
1.79
1.52
7.92
7.72
7.42
7.02
6.60
6.15
5.73
5.32
4.95
4.58
4.23
3.92
3.62
8.75
8.54
8.24
7.83
7.40
6.94
6.52
6.12
5.73
5.35
5.00
4.68
4.38
S
21
ANG
deg
168.8
157.3
145.9
135.5
125.3
116.0
107.2
98.9
90.6
83.0
75.3
67.5
60.4
168.9
157.6
146.7
136.4
126.5
117.4
108.9
100.8
92.8
85.4
78.1
70.6
63.9
169.1
157.8
147.0
136.7
126.8
117.9
109.3
101.5
93.6
86.4
79.0
71.7
65.2
LOG
MAG
dB
–55.94
–50.26
–47.29
–45.68
–44.98
–44.62
–45.51
–45.88
–46.46
–47.88
–49.66
–49.70
–47.29
–55.74
–49.95
–47.09
–45.38
–44.69
–44.43
–45.21
–45.48
–46.06
–47.18
–48.75
–48.80
–46.98
–55.44
–49.75
–46.89
–45.18
–44.49
–44.23
–44.91
–45.08
–45.56
–46.48
–47.85
–48.20
–46.78
S
12
ANG
deg
83.6
76.8
70.6
65.5
60.1
58.6
56.2
58.4
64.0
70.0
89.8
116.0
145.4
83.2
76.8
70.5
65.4
60.1
58.8
57.0
59.5
65.2
71.5
89.0
111.9
139.8
83.4
76.8
70.5
65.5
60.3
59.4
57.6
60.2
65.8
71.4
87.0
107.0
133.8
LOG
MAG
dB
–0.08
–0.13
–0.21
–0.28
–0.37
–0.47
–0.55
–0.65
–0.72
–0.77
–0.82
–0.89
–0.89
–0.10
–0.16
–0.24
–0.33
–0.43
–0.53
–0.61
–0.72
–0.79
–0.85
–0.90
–0.96
–0.97
–0.13
–0.19
–0.28
–0.35
–0.46
–0.57
–0.66
–0.76
–0.84
–0.90
–0.95
–1.00
–1.01
S
22
ANG
deg
–3.6
–7.0
–10.4
–13.5
–16.7
–19.5
–22.5
–25.1
–28.2
–30.9
–33.7
–36.7
–39.6
–3.6
–7.1
–10.5
–13.8
–17.1
–19.8
–22.6
–25.4
–28.4
–31.1
–33.8
–36.9
–39.7
–3.7
–7.2
–10.6
–13.9
–17.2
–20.0
–22.8
–25.7
–28.6
–31.3
–34.0
–36.9
–39.9
5
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
8
10
15
TELEFUNKEN Semiconductors
Rev. A2, 07-Mar-97
3 (8)
BF998/BF998R
Typical Characteristics
(T
j
= 25
_
C unless otherwise specified)
300
P
tot
– Total Power Dissipation ( mW )
20
250
I
D
– Drain Current ( mA )
16
12
8
0
4
V
G1S
= –1V
0
0
96 12159
4V
V
DS
= 8V
5V
3V
2V
1V
200
150
100
50
20
40
60
80
100 120 140 160
12817
0
–0.6
–0.2
0.2
0.6
1.0
1.4
T
amb
– Ambient Temperature (
°C
)
V
G2S
– Gate 2 Source Voltage ( V )
Figure 1. Total Power Dissipation vs. Ambient Temperature
32
28
I
D
– Drain Current ( mA )
24
20
16
12
0
8
4
–0.4V
0
0
12812
Figure 4. Drain Current vs. Gate 2 Source Voltage
3.0
V
G2S
= 4V
V
G1S
= 0.6V
C
issg1
– Gate 1 Input Capacitance ( pF )
2.5
2.0
1.5
1.0
0.5
0
–2
V
DS
=8V
V
G2S
=4V
f=1MHz
0.4V
0.2V
–0.2V
1
2
3
4
5
6
7
8
9
10
12863
–1.5 –1.0 –0.5
0.0
0.5
1.0
1.5
V
DS
– Drain Source Voltage ( V )
V
G1S
– Gate 1 Source Voltage ( V )
Figure 2. Drain Current vs. Drain Source Voltage
20
Figure 5. Gate 1 Input Capacitance vs. Gate 1 Source Voltage
3.0
C
oss
– Output Capacitance ( pF )
V
DS
= 8V
I
D
– Drain Current ( mA )
16
12
8
4
0
–0.8
12816
6V
5V
4V
3V
2V
1V
2.5
2.0
1.5
1.0
0.5
0
V
G2S
=4V
f=1MHz
0
V
G2S
=–1V
–0.4
0.0
0.4
0.8
1.2
2
12864
4
6
8
10
12
V
G1S
– Gate 1 Source Voltage ( V )
V
DS
– Drain Source Voltage ( V )
Figure 3. Drain Current vs. Gate 1 Source Voltage
Figure 6. Output Capacitance vs. Drain Source Voltage
4 (8)
TELEFUNKEN Semiconductors
Rev. A2, 07-Mar-97
BF998/BF998R
10
f= 800MHz
– Transducer Gain ( dB )
0
–10
–20
–0.2V
–30
–0.4V
–40
–50
–1
12818
4V
3V
2V
1V
0
Im ( y ) ( mS )
21
5
0
–5
–10
–15
–20
–25
–30
–35
–40
1300MHz
0
12821
V
DS
=8V
V
G2S
=4V
f=100...1300MHz
I
D
=5mA
10mA
20mA
f=100MHz
400MHz
700MHz
1000MHz
S
21
2
V
G2S
=–0.8V
–0.5
0.0
0.5
1.0
1.5
4
8
12
16
20
24
28
32
V
G1S
– Gate 1 Source Voltage ( V )
Re (y
21
) ( mS )
Figure 7. Transducer Gain vs. Gate 1 Source Voltage
32
28
24
20
16
12
8
4
0
0
0
12819
Figure 10. Short Circuit Forward Transfer Admittance
9
y
21s
– Forward Transadmittance ( mS )
V
DS
=8V
f=1MHz
V
G2S
=4V
3V
Im ( y ) ( mS )
22
8
7
6
5
4
3
2
f=1300MHz
1000MHz
700MHz
400MHz
100MHz
0
0.25
0.50
0.75
V
DS
=15V
V
G2S
=4V
I
D
=10mA
f=100...1300MHz
1.00
1.25
1.50
2V
1V
1
0
20
24
28
12822
4
8
12
16
I
D
– Drain Current ( mA )
Re (y
22
) ( mS )
Figure 8. Forward Transadmittance vs. Drain Current
20
18
16
14
Im ( y ) ( mS )
11
12
10
8
6
4
2
0
0
12820
Figure 11. Short Circuit Output Admittance
f=1300MHz
1000MHz
700MHz
V
DS
=8V
V
G2S
=4V
I
D
=10mA
f=100...1300MHz
6
8
10
12
14
400MHz
100MHz
2
4
Re (y
11
) ( mS )
Figure 9. Short Circuit Input Admittance
TELEFUNKEN Semiconductors
Rev. A2, 07-Mar-97
5 (8)
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