VISHAY
BF998 / BF998R / BF998RW
Vishay Semiconductors
N-Channel Dual Gate MOS-Fieldeffect Tetrode, Depletion Mode
2
1
SOT-143
Features
•
•
•
•
•
•
•
Integrated gate protection diodes
Low noise figure
Low feedback capacitance
High cross modulation performance
Low input capacitance
High AGC-range
High gain
3
1
4
2
SOT-143R
4
1
3
2
SOT-343R
Applications
Input and mixer stages in UHF tuners.
Mechanical Data
Typ:
BF998
Case:
SOT-143 Plastic case
Weight:
approx. 8.0 mg
Marking:
MO
Pinning:
1 = Source, 2 = Drain,
3 = Gate 2, 4 = Gate 1
Typ:
BF998R
Case:
SOT-143R Plastic case
Weight:
approx. 8.0 mg
Marking:
MOR
Pinning:
1 = Source, 2 = Drain,
3 = Gate 2, 4 = Gate 1
4
3
19216
Electrostatic sensitive device.
Observe precautions for handling.
Typ:
BF998RW
Case:
SOT-343R Plastic case
Weight:
approx. 6.0 mg
Marking:
WMO
Pinning:
1 = Source, 2 = Drain,
3 = Gate 2, 4 = Gate 1
Absolute Maximum Ratings
T
amb
= 25 °C, unless otherwise specified
Parameter
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
Test condition
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 to + 150
Unit
V
mA
mA
V
mW
°C
°C
Document Number 85011
Rev. 1.5, 31-Aug-04
www.vishay.com
1
BF998 / BF998R / BF998RW
Vishay Semiconductors
Maximum Thermal Resistance
Parameter
Channel ambient
1)
1)
VISHAY
Test condition
Symbol
R
thChA
Value
450
Unit
K/W
on glass fibre printed board (25 x 20 x 1.5) mm
3
plated with 35
µm
Cu
Electrical DC Characteristics
T
amb
= 25 °C, unless otherwise specified
Parameter
Drain - source breakdown
voltage
Gate 1 - source breakdown
voltage
Gate 2 - source breakdown
voltage
Test condition
I
D
= 10
µA,
- V
G1S
= - V
G2S
= 4 V
± I
G1S
= 10 mA, V
G2S
= V
DS
= 0
± I
G2S
= 10 mA, V
G1S
= V
DS
= 0
Part
Symbol
V
(BR)DS
± V
(BR)G1SS
± V
(BR)G2SS
± I
G1SS
± I
G2SS
BF998/
BF998R/
BF998RW
BF998A/
BF998RA/
BF998RAW
BF998B/
BF998RB/
BF998RBW
Gate 1 - source cut-off voltage
Gate 2 - source cut-off voltage
V
DS
= 8 V, V
G2S
= 4 V, I
D
= 20
µA
V
DS
= 8 V, V
G1S
= 0, I
D
= 20
µA
I
DSS
4
Min
12
7
7
14
14
50
50
18
Typ.
Max
Unit
V
V
V
nA
nA
mA
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
I
DSS
4
10.5
mA
I
DSS
9.5
18
mA
- V
G1S(OFF)
- V
G2S(OFF)
1.0
0.6
2.0
1.0
V
V
Electrical AC Characteristics
T
amb
= 25 °C, unless otherwise specified
V
DS
= 8 V, I
D
= 10 mA, V
G2S
= 4 V, f = 1 MHz
Parameter
Forward transadmittance
Gate 1 input capacitance
Gate 2 input capacitance
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
Noise figure
V
G2S
= 4 to -2 V, f = 800 MHz
G
S
= 2 mS, G
L
= 0.5 mS,
f = 200 MHz
G
S
= 3,3 mS, G
L
= 1 mS,
f = 800 MHz
V
G1S
= 0, V
G2S
= 4 V
Test condition
Symbol
|y
21s
|
C
issg1
C
issg2
C
rss
C
oss
G
ps
G
ps
∆G
ps
F
F
16.5
40
1.0
1.5
Min
21
Typ.
24
2.1
1.1
25
1.05
28
20
2.5
Max
Unit
mS
pF
pF
fF
pF
dB
dB
dB
dB
dB
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2
Document Number 85011
Rev. 1.5, 31-Aug-04
VISHAY
BF998 / BF998R / BF998RW
Vishay Semiconductors
Typical Characteristics
(T
amb
= 25
°C
unless otherwise specified)
300
20
I
D
– Drain Current ( mA)
P
tot
-Total
Power Dissipation ( mW )
250
200
150
100
50
0
0
20
40
60
80
100 120 140 160
T
amb
- Ambient Temperature (
°C
)
V
DS
= 8 V
5V
4V
3V
2V
1V
16
12
8
4
0
–0.6
0
V
G1S
= –1 V
–0.2
0.2
0.6
1.0
1.4
V
G2S
– Gate 2 Source Voltage ( V )
96 12159
12817
Figure 1. Total Power Dissipation vs. Ambient Temperature
Figure 4. Drain Current vs. Gate 2 Source Voltage
30
25
20
15
10
5
0
0
12812
C
issg1
– Gate 1 Input Capacitance ( pF )
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-2
-1.5
-1
-0.5
0
0.5
1.0
1.5
V
G1S
– Gate 1 Source Voltage ( V )
V
DS
= 8 V
V
G2S
= 4 V
f = 1 MHz
V
G2S
= 4 V
V
G1S
= 0.6 V
I
D
– Drain Current ( mA )
0.4 V
0.2 V
0
–0.2 V
–0.4 V
2
4
6
8
10
V
DS
– Drain Source Voltage ( V )
12863
Figure 2. Drain Current vs. Drain Source Voltage
Figure 5. Gate 1 Input Capacitance vs. Gate 1 Source Voltage
V
DS
= 8 V
I
D
– Drain Current ( mA)
6V
5V
4V
C
oss
– Output Capacitance ( pF )
20
16
12
8
4
0
–0.8
12816
3V
2V
1V
3.0
2.5
2.0
1.5
1.0
0.5
0.0
2
V
G2S
= 4 V
f = 1 MHz
0
V
G2S
= –1 V
–0.4
0.0
0.4
0.8
1.2
V
G1S
– Gate 1 Source Voltage ( V )
12864
4
6
8
10
12
V
DS
– Drain Source Voltage ( V )
Figure 3. Drain Current vs. Gate 1 Source Voltage
Figure 6. Output Capacitance vs. Drain Source Voltage
Document Number 85011
Rev. 1.5, 31-Aug-04
www.vishay.com
3
BF998 / BF998R / BF998RW
Vishay Semiconductors
VISHAY
10
- Transducer Gain ( dB )
f = 800 MHz
0
–10
–20
–30
4V
3V
2V
1V
Im ( y ) ( mS )
21
5
0
–5
–10
–15
–20
–25
–30
–35
–40
0
12821
V
DS
= 8 V
V
G2S
= 4 V
f = 100...1300 MHz
I
D
= 5 mA
10 mA
20 mA
f = 100 MHz
0
–0.2 V
–0.4 V
–40
–50
–1.0
V
G2S
= –0.8 V
400 MHz
700 MHz
1000 MHz
S
21
2
1300 MHz
4
8
12 16 20 24
Re (y
21
) ( mS )
28
32
–0.5
0.0
0.5
1.0
1.5
12818
V
G1S
– Gate 1 Source Voltage ( V )
Figure 7. Transducer Gain vs. Gate 1 Source Voltage
Figure 10. Short Circuit Forward Transfer Admittance
y
21s
– Forward Transadmittance ( mS )
32
28
24
20
16
12
8
4
0
0
0
4
8
12
16
20
24
28
12822
9
V
DS
= 8 V
f = 1 MHz
V
G2S
= 4 V
3V
Im ( y ) ( mS )
22
8
7
6
5
4
3
2
1
0
0.00
f = 1300 MHz
1000 MHz
700 MHz
400 MHz
100 MHz
0.25
V
DS
= 15 V
V
G2S
= 4 V
I
D
=10 mA
f = 100...1300 MHz
1.25
1.50
2V
1V
12819
I
D
– Drain Current ( mA )
0.50 0.75 1.00
Re (y
22
) ( mS )
Figure 8. Forward Transadmittance vs. Drain Current
Figure 11. Short Circuit Output Admittance
20
18
16
Im ( y ) ( mS )
11
f = 1300 MHz
14
12
10
8
6
4
2
0
0
400 MHz
100 MHz
2
4
700 MHz
1000 MHz
V
DS
= 8 V
V
G2S
= 4 V
I
D
= 10 mA
f = 100...1300 MHz
12
14
12820
6
8
10
Re (y
11
) ( mS )
Figure 9. Short Circuit Input Admittance
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4
Document Number 85011
Rev. 1.5, 31-Aug-04
VISHAY
V
DS
= 8 V, I
D
= 10 mA, V
G2S
= 4 V, Z
0
= 50
Ω
S
11
j
j0.5
j0.2
j2
BF998 / BF998R / BF998RW
Vishay Semiconductors
S
21
90 °
700
1000
30 °
1300 MHz
100
180 °
1
2
0°
120 °
400
150 °
j5
60 °
0
–j0.2
0.2
0.5
1
2
5
100
–j5
–150°
–120 °
–60 °
–30°
1300 MHz
1000
–j0.5
–j2
–j
12960
12962
–90 °
Figure 12. Input Reflection Coefficient
Figure 14. Forward Transmission Coefficient
S
12
90 °
S
22
j
60 °
30 °
1200
200
100
j0.5
j2
120 °
150 °
1300 MHz
180 °
j0.2
j5
0.08
0.16
0°
0
0.2
0.5
1
2
5
100
–j5
–j0.2
–150 °
–120 °
–60 °
–30 °
–j0.5
12973
1300 MHz
–j2
–j
–90 °
12963
Figure 13. Reverse Transmission Coefficient
Figure 15. Output Reflection Coefficient
Document Number 85011
Rev. 1.5, 31-Aug-04
www.vishay.com
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