PHILIPS BF908

DISCRETE SEMICONDUCTORS
DATA SHEET
BF908; BF908R
Dual-gate MOS-FETs
Product specification
Supersedes data of April 1995
File under Discrete Semiconductors, SC07
1996 Jul 30
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
BF908; BF908R
FEATURES
• High forward transfer admittance
d
handbook, halfpage
• Short channel transistor with high forward transfer
admittance to input capacitance ratio
4
3
g2
• Low noise gain controlled amplifier up to 1 GHz.
g1
APPLICATIONS
• VHF and UHF applications with 12 V supply voltage,
such as television tuners and professional
communications equipment.
1
2
s,b
Top view
MAM039
DESCRIPTION
Fig.1
Depletion type field-effect transistor in a plastic
microminiature SOT143 or SOT143R package. The
transistors are protected against excessive input voltage
surges by integrated back-to-back diodes between gates
and source.
Simplified outline (SOT143) and
symbol; BF908.
d
handbook, halfpage
3
CAUTION
4
The device is supplied in an antistatic package. The
gate-source input must be protected against static
discharge during transport or handling.
g2
g1
PINNING
2
PIN
SYMBOL
1
s, b
2
d
drain
3
g2
gate 2
4
g1
gate 1
1
s,b
DESCRIPTION
Top view
MAM040
source
Fig.2
Simplified outline (SOT143R) and
symbol; BF908R.
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
VDS
drain-source voltage
−
−
12
V
ID
drain current
−
−
40
mA
Ptot
total power dissipation
−
−
200
mW
Tj
operating junction temperature
−
−
150
°C
yfs
forward transfer admittance
36
43
50
mS
Cig1-s
input capacitance at gate 1
2.4
3.1
4
pF
Crs
reverse transfer capacitance
f = 1 MHz
20
30
45
pF
F
noise figure
f = 800 MHz
−
1.5
2.5
dB
1996 Jul 30
2
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
BF908; BF908R
LIMITING VALUES
In accordance with the Absolute Maximum Rating System (IEC 134).
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
VDS
drain-source voltage
−
12
V
ID
drain current
−
40
mA
±IG1
gate 1 current
−
10
mA
±IG2
gate 2 current
−
10
mA
Ptot
total power dissipation
see Fig.3; note 1
BF908
up to Tamb = 50 °C
−
200
mW
BF908R
up to Tamb = 40 °C
−
200
mW
Tstg
storage temperature
−65
+150
°C
Tj
operating junction temperature
−
150
°C
Note
1. Device mounted on a printed-circuit board.
MRC275
250
handbook, halfpage
P
tot
(mW)
200
BF908
150
BF908R
100
50
0
0
50
100
150
200
o
Tamb ( C)
Fig.3 Power derating curves.
1996 Jul 30
3
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
BF908; BF908R
THERMAL CHARACTERISTICS
SYMBOL
Rth j-a
PARAMETER
CONDITIONS
VALUE
UNIT
BF908
500
K/W
BF908R
550
K/W
thermal resistance from junction to ambient
note 1
Note
1. Device mounted on a printed-circuit board.
STATIC CHARACTERISTICS
Tj = 25 °C; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
±V(BR)G1-SS gate 1-source breakdown voltage
VG2-S = VDS = 0; IG1-S = 10 mA
8
−
20
V
±V(BR)G2-SS gate 2-source breakdown voltage
VG1-S = VDS = 0; IG2-S = 10 mA
8
−
20
V
−V(P)G1-S
gate 1-source cut-off voltage
VG2-S = 4 V; VDS = 8 V; ID = 20 µA −
−
2
V
−V(P)G2-S
gate 2-source cut-off voltage
VG1-S = 4 V; VDS = 8 V; ID = 20 µA −
−
1.5
V
IDSS
drain-source current
VG2-S = 4 V; VDS = 8 V; VG1-S = 0
3
15
27
mA
±IG1-SS
gate 1 cut-off current
VG2-S = VDS = 0; VG1-S = 5 V
−
−
50
nA
±IG2-SS
gate 2 cut-off current
VG1-S = VDS = 0; VG2-S = 5 V
−
−
50
nA
MAX.
UNIT
DYNAMIC CHARACTERISTICS
Common source; Tamb = 25 °C; VDS = 8 V; VG2-S = 4 V; ID = 15 mA; unless otherwise specified.
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
yfs
forward transfer admittance
pulsed; Tj = 25 °C; f = 1 MHz
36
43
50
mS
Cig1-s
input capacitance at gate 1
f = 1 MHz
2.4
3.1
4
pF
Cig2-s
input capacitance at gate 2
f = 1 MHz
1.2
1.8
2.5
pF
Cos
output capacitance
f = 1 MHz
1.2
1.7
2.2
pF
Crs
reverse transfer capacitance
f = 1 MHz
20
30
45
fF
F
noise figure
f = 200 MHz; GS = 2 mS; BS = BSopt
−
0.6
1.2
dB
f = 800 MHz; GS = GSopt; BS = BSopt
−
1.5
2.5
dB
1996 Jul 30
4
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
BF908; BF908R
MRC282
MRC281
40
handbook, halfpage
30
handbook, halfpage
VG2-S = 4 V
ID
(mA)
ID
(mA)
3V
30
VG1-S = 0.3 V
0.2 V
2V
20
0.1 V
1.5 V
1V
20
0V
0.5 V
10
−0.1 V
10
−0.2 V
−0.3 V
0V
0
−0.6
−0.4
0
−0.2
0
0.2
0.4
0
0.6
4
8
12
16
VDS (V)
VG1-S (V)
VDS = 8 V; Tj = 25 °C.
VG2-S = 4 V; Tj = 25 °C.
Fig.4 Transfer characteristics; typical values.
Fig.5 Output characteristics; typical values.
MRC280
50
Yfs
(mS)
40
MRC276
60
4V
3V
2V
Yfs
(mS)
1.5 V
40
30
1V
20
20
0.5 V
10
VG2-S = 0 V
0
0
0
5
10
15
20
40
25
I D (mA)
VDS = 8 V; Tj = 25 °C.
Fig.6
1996 Jul 30
0
40
80
120
160
T j (o C)
VDS = 8 V; VG2-S = 4 V; ID = 15 mA.
Forward transfer admittance as a function
of drain current; typical values.
Fig.7
5
Forward transfer admittance as a function
of junction temperature; typical values.
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
Table 1
f
(MHz)
BF908; BF908R
Scattering parameters
s11
MAGNITUDE
(ratio)
s21
ANGLE
(deg)
MAGNITUDE
(ratio)
s12
ANGLE
(deg)
MAGNITUDE
(ratio)
s22
ANGLE
(deg)
MAGNITUDE
(ratio)
ANGLE
(deg)
VDS = 8 V; VG2-S = 4 V; ID = 10 mA; Tamb = 25 °C.
50
0.998
−5.1
3.537
173.5
0.001
98.2
0.996
−2.4
100
0.994
−10.4
3.502
167.7
0.001
88.8
0.994
−4.9
200
0.979
−20.8
3.450
154.9
0.003
74.6
0.987
−9.5
300
0.962
−30.3
3.318
143.7
0.004
69.5
0.983
−13.9
400
0.939
−40.1
3.234
131.9
0.005
65.6
0.980
−18.5
500
0.914
−49.1
3.093
120.7
0.006
64.4
0.974
−22.8
600
0.892
−57.1
2.912
111.1
0.005
63.1
0.969
−27.0
700
0.865
−64.4
2.774
101.0
0.005
65.2
0.966
−31.2
800
0.837
−71.6
2.616
91.4
0.004
70.8
0.965
−35.4
900
0.811
−78.1
2.479
81.9
0.004
87.4
0.965
−39.4
1000
0.785
−84.5
3.329
72.5
0.003
108.0
0.966
−43.7
VDS = 8 V; VG2-S = 4 V; ID = 15 mA; Tamb = 25 °C.
50
0.998
−5.3
3.983
173.4
0.001
95.5
0.994
−2.4
100
0.994
−10.9
3.943
167.5
0.001
93.6
0.991
−5.0
200
0.976
−21.6
3.878
154.7
0.003
74.3
0.984
−9.7
300
0.957
−31.7
3.722
143.3
0.004
70.0
0.979
−14.2
400
0.934
−41.7
3.614
131.6
0.005
63.5
0.975
−18.8
500
0.907
−51.1
3.446
120.4
0.006
62.2
0.969
−23.2
600
0.885
−59.1
3.240
110.9
0.005
59.6
0.964
−27.4
700
0.851
−66.8
3.072
100.9
0.005
64.8
0.961
−31.6
800
0.826
−73.9
2.891
91.3
0.004
67.8
0.959
−35.9
900
0.797
−80.7
2.733
81.9
0.004
85.0
0.958
−40.0
1000
0.773
−87.0
2.569
72.8
0.004
102.9
0.958
−44.2
Table 2
Noise data
f
(MHz)
Fmin
(dB)
Γopt
rn
(ratio)
(deg)
0.720
56.7
0.580
0.700
59.2
0.520
VDS = 8 V; VG2-S = 4 V; ID = 10 mA; Tamb = 25 °C.
800
1.50
VDS = 8 V; VG2-S = 4 V; ID = 15 mA; Tamb = 25 °C.
800
1996 Jul 30
1.50
6
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
BF908; BF908R
PACKAGE OUTLINES
handbook, full pagewidth
3.0
2.8
0.150
0.090
0.75
0.60
B
1.9
4
3
0.1
max
o
10
max
0.2 M A B
A
2.5
max
1.4
1.2
o
10
max
1
1.1
max
o
30
max
2
0
0.1
0.88
0.48
0.1 M A B
0
0.1
MBC845
1.7
TOP VIEW
Dimensions in mm.
Fig.8 SOT143.
3.0
2.8
handbook, full pagewidth
0.150
0.090
0.40
0.25
B
1.9
3
4
0.1
max
o
10
max
0.2 M A
A
1.4
1.2
o
2.5
max
10
max
2
1.1
max
o
30
max
1
0.48
0.38
0.88
0.78
1.7
0.1 M B
TOP VIEW
Dimensions in mm.
Fig.9 SOT143R.
1996 Jul 30
7
MBC844
Philips Semiconductors
Product specification
Dual-gate MOS-FETs
BF908; BF908R
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.
1996 Jul 30
8