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DISCRETE SEMICONDUCTORS
DATA SH EET
BF908WR
N-channel dual-gate MOS-FET
Preliminary specification
File under Discrete Semiconductors, SC07
Philips Semiconductors
1995 Apr 25
Page 2
Philips Semiconductors Preliminary specification
N-channel dual-gate MOS-FET BF908WR
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. 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
3g
4g
34
21
Top view
Marking code: MD.
gate 2
2
gate 1
1
MAM198
g
2
g
1
Fig.1 Simplified outline (SOT343R) and symbol.
d
s,b
QUICK REFERENCE DATA
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
V
DS
I
D
P
tot
T
j
forward transfer admittance 36 43 50 mS
y
fs
C
ig1-s
C
rs
drain-source voltage −−12 V
drain current −−40 mA
total power dissipation −−300 mW
operating junction temperature −−150 °C
input capacitance at gate 1 2.4 3.1 4 pF
reverse transfer capacitance f = 1 MHz 20 30 45 fF
F noise figure f = 800 MHz − 1.5 2.5 dB
1995 Apr 25 2
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Philips Semiconductors Preliminary specification
N-channel dual-gate MOS-FET BF908WR
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT
V
DS
I
D
I
G1
I
G2
P
tot
T
stg
T
j
Note
1. Device mounted on a printed-circuit board.
drain-source voltage − 12 V
drain current − 40 mA
gate 1 current −±10 mA
gate 2 current −±10 mA
total power dissipation up to T
=45°C; see Fig.2;
amb
− 300 mW
note 1
storage temperature −65 +150 °C
operating junction temperature − +150 °C
400
handbook, halfpage
P
tot
(mW)
300
200
100
0
0 50 100 200
150
T ( C)
amb
Fig.2 Power derating curve.
MLD154
o
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Philips Semiconductors Preliminary specification
N-channel dual-gate MOS-FET BF908WR
THERMAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS VALUE UNIT
R
th j-a
R
th j-s
Notes
1. Device mounted on a printed-circuit board.
2. Ts is the temperature at the soldering point of the source lead.
STATIC CHARACTERISTICS
=25°C; unless otherwise specified.
T
j
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
V
(BR)G1-SS
V
(BR)G2-SS
V
(P)G1-S
V
(P)G2-S
I
DSS
I
G1-SS
I
G2-SS
thermal resistance from junction to ambient note 1 350 K/W
thermal resistance from junction to soldering point Ts=87°C; note 2 210 K/W
gate 1-source breakdown voltage V
gate 2-source breakdown voltage V
gate 1-source cut-off voltage V
gate 2-source cut-off voltage V
drain-source current V
gate 1 cut-off current V
gate 2 cut-off current V
G2-S=VDS
G1-S=VDS
G2-S
G1-S
G2-S
G2-S=VDS
G1-S=VDS
= 0; I
= 0; I
=10mA 8 − 20 V
G1-S
=10mA 8 − 20 V
G2-S
=4V; VDS=8V; ID=20µA −−−2V
=4V; VDS=8V; ID=20µA −−−1.5 V
=4V; VDS=8V; V
= 0; V
G1-S
= 0; V
G2-S
=0 3 15 27 mA
G1-S
=5V −−50 nA
=5V −−50 nA
DYNAMIC CHARACTERISTICS
Common source; T
=25°C; VDS=8V;V
amb
= 4 V; ID= 15 mA; unless otherwise specified.
G2-S
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
y
forward transfer admittance pulsed; Tj=25°C 364350mS
fs
C
ig1-s
C
ig2-s
C
os
C
rs
F noise figure f = 200 MHz; G
input capacitance at gate 1 f = 1 MHz 2.4 3.1 4 pF
input capacitance at gate 2 f = 1 MHz 1.2 1.8 2.5 pF
drain-source capacitance f = 1 MHz 1.2 1.7 2.2 pF
reverse transfer capacitance f = 1 MHz 20 30 45 fF
f = 800 MHz; G
= 2 mS; BS=B
S
S=GSopt
; BS=B
Sopt
Sopt
− 0.6 1.2 dB
− 1.5 2.5 dB
1995 Apr 25 4
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Philips Semiconductors Preliminary specification
N-channel dual-gate MOS-FET BF908WR
40
handbook, halfpage
I
D
(mA)
30
20
10
0
VDS=8V.
Tj=25°C.
G2-S
0 0.2 0.4 0.6–0.2–0.4–0.6
Fig.3 Transfer characteristics; typical values.
= 4 VV
V
G1-S
MRC281
3 V
2 V
1.5 V
1 V
0.5 V
0 V
(V)
30
handbook, halfpage
I
D
(mA)
20
10
0
04812
V
=4V.
G2-S
Tj=25°C.
Fig.4 Output characteristics; typical values.
MRC282
V =
G1-S
0.3 V
0.2 V
0.1 V
0 V
–0.1 V
–0.2 V
–0.3 V
V (V)
DS
16
50
Y
fs
(mS)
40
30
20
10
0
VDS=8V.
Tj=25°C.
0.5 V
V
= 0 V
G2-S
0 5 10 15 20 25
MRC280
4 V
3 V
2 V
1.5 V
1 V
ID(mA)
Fig.5 Forward transfer admittance as a function
of drain current; typical values.
MRC276
o
Tj( C)
Y
fs
(mS)
60
40
20
0
0 40 80 120 16040
Fig.6 Forward transfer admittance as a function
of junction temperature; typical values.
1995 Apr 25 5
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Philips Semiconductors Preliminary specification
N-channel dual-gate MOS-FET BF908WR
PACKAGE OUTLINE
1.00
max
0.2
A
M
0.2
M
34
0.4
B
0.2
A
0.1
max
0.2
Dimensions in mm.
2.2
2.0
21
0.7
0.5
1.4
1.2
2.2
1.8
Fig.7 SOT343R.
1.35
1.15
B
0.3
0.1
0.25
0.10
MSB367
1995 Apr 25 6
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Philips Semiconductors Preliminary specification
N-channel dual-gate MOS-FET BF908WR
DEFINITIONS
Data Sheet Status
Objective specification This data sheet contains target or goal specifications for product development.
Preliminary specification This data sheet contains preliminary data; supplementary data may be published later.
Product specification This data sheet contains final product specifications.
Limiting values
Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.
1995 Apr 25 7
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