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NXP Semiconductors
BF908; BF908R
Dual-gate MOS-FETs
Rev. 03 — 14 November 2007 Product data sheet
NXP Semiconductors Product specification
Dual-gate MOS-FETs BF908; BF908R
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 SOT143 or SOT143R package. The
transistors are protected against excessive input voltage
surges by integrated back-to-back diodes between gates
and source.
PINNING
CAUTION
The device is supplied in an antistatic package. The
gate-source input must be protected against static
discharge during transport or handling.
PIN SYMBOL DESCRIPTION
1 s, b source
2 d drain
3g
2
gate 2
4g
1
gate 1
Fig.1 Simplified outline (SOT143) and
symbol; BF908.
handbook, halfpage
s,b
d
g1
g2
43
21
Top view
BF908 marking code: %M1.
MAM039
Fig.2 Simplified outline (SOT143R) and
symbol; BF908R.
handbook, halfpage
s,b
d
g1
g2
MAM040
34
12
Top view
BF908R marking code: %M2.
QUICK REFERENCE DATA
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
VDS drain-source voltage −−12 V
IDdrain current −−40 mA
Ptot total power dissipation −−200 mW
Tjoperating junction temperature −−150 °C
yfsforward 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
Rev. 03 - 14 November 2007
2 of 9
NXP Semiconductors Product specification
Dual-gate MOS-FETs BF908; BF908R
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
VDS drain-source voltage −12 V
IDdrain 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
Tjoperating junction temperature −150 °C
Fig.3 Power derating curves.
handbook, halfpage
0
50
100
150
200
250
0 50 100 150 200
BF908
BF908R
P
tot
(mW)
Tamb ( C)
o
MRC275
Rev. 03 - 14 November 2007
3 of 9
NXP Semiconductors Product specification
Dual-gate MOS-FETs BF908; BF908R
THERMAL CHARACTERISTICS
Note
1. Device mounted on a printed-circuit board.
STATIC CHARACTERISTICS
Tj=25°C; unless otherwise specified.
DYNAMIC CHARACTERISTICS
Common source; Tamb =25°C; VDS =8V; V
G2-S =4V; I
D= 15 mA; unless otherwise specified.
SYMBOL PARAMETER CONDITIONS VALUE UNIT
Rth j-a thermal resistance from junction to ambient note 1
BF908 500 K/W
BF908R 550 K/W
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
±V(BR)G1-SS gate 1-source breakdown voltage VG2-S =V
DS = 0; IG1-S =10mA 8 −20 V
±V(BR)G2-SS gate 2-source breakdown voltage VG1-S =V
DS = 0; IG2-S =10mA 8 −20 V
−V(P)G1-S gate 1-source cut-off voltage VG2-S =4V; V
DS =8V; I
D=20µA−−2V
−V
(P)G2-S gate 2-source cut-off voltage VG1-S =4V; V
DS =8V; I
D=20µA−−1.5 V
IDSS drain-source current VG2-S =4V; V
DS =8V; V
G1-S =03 1527mA
±I
G1-SS gate 1 cut-off current VG2-S =V
DS = 0; VG1-S =5V −−50 nA
±IG2-SS gate 2 cut-off current VG1-S =V
DS = 0; VG2-S =5V −−50 nA
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
yfsforward 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=B
Sopt −0.6 1.2 dB
f = 800 MHz; GS=G
Sopt; BS=B
Sopt −1.5 2.5 dB
Rev. 03 - 14 November 2007
4 of 9
NXP Semiconductors Product specification
Dual-gate MOS-FETs BF908; BF908R
Fig.4 Transfer characteristics; typical values.
VDS = 8 V; Tj=25°C.
handbook, halfpage
−0.6 −0.4 0 0.2−0.2 0.4
VG1-S (V)
3 V
2 V
1.5 V
0.5 V
0 V
0.6
40
30
10
0
20
MRC281
VG2-S = 4 V
1 V
ID
(mA)
Fig.5 Output characteristics; typical values.
VG2-S = 4 V; Tj=25°C.
handbook, halfpage
048 16
30
10
0
20
MRC282
12 VDS (V)
ID
(mA) 0.2 V
0.1 V
0 V
−0.3 V
−0.2 V
−0.1 V
VG1-S = 0.3 V
Fig.6 Forward transfer admittance as a function
of drain current; typical values.
VDS = 8 V; Tj=25°C.
0
10
20
30
40
50
0 5 10 15 20 25
0.5 V
1 V
1.5 V
2 V
3 V
4 V
VG2-S = 0 V
Yfs
(mS)
ID(mA)
MRC280
Fig.7 Forward transfer admittance as a function
of junction temperature; typical values.
0
20
40
60
0 40 80 120 16040
Yfs
(mS)
Tj( C)
o
MRC276
VDS = 8 V; VG2-S = 4 V; ID=15mA.
Rev. 03 - 14 November 2007
5 of 9
NXP Semiconductors Product specification
Dual-gate MOS-FETs BF908; BF908R
Table 1 Scattering parameters
Table 2 Noise data
f
(MHz)
s11 s21 s12 s22
MAGNITUDE
(ratio) ANGLE
(deg) MAGNITUDE
(ratio) ANGLE
(deg) MAGNITUDE
(ratio) ANGLE
(deg) MAGNITUDE
(ratio) ANGLE
(deg)
VDS =8V; V
G2-S =4V; I
D= 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 =8V; V
G2-S =4V; I
D= 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
f
(MHz) Fmin
(dB) Γopt rn
(ratio) (deg)
VDS =8V; V
G2-S =4V; I
D= 10 mA; Tamb =25°C.
800 1.50 0.720 56.7 0.580
VDS =8V; V
G2-S =4V; I
D= 15 mA; Tamb =25°C.
800 1.50 0.700 59.2 0.520
Rev. 03 - 14 November 2007
6 of 9
NXP Semiconductors Product specification
Dual-gate MOS-FETs BF908; BF908R
PACKAGE OUTLINES
Fig.8 SOT143.
Dimensions in mm.
handbook, full pagewidth
MBC845
10
max
o
10
max
o
30
max
o
1.1
max
0.75
0.60
0.150
0.090
0.1
max
43
2
M0.1 AB
0
0.1
0.48
TOP VIEW
1.4
1.2 2.5
max
3.0
2.8
M
0.2 AB
A
B
1.9
1
0
0.1
0.88
1.7
Fig.9 SOT143R.
Dimensions in mm.
handbook, full pagewidth
MBC844
10
max
o
10
max
o
30
max
o
1.1
max
0.40
0.25
0.150
0.090
0.1
max
34
2
1.4
1.2 2.5
max
3.0
2.8
A
B
1.9 M
0.2 A
1
M0.1 B
TOP VIEW
0.48
0.38 0.88
0.78
1.7
Rev. 03 - 14 November 2007
7 of 9
NXP Semiconductors BF908; BF908R
Dual-gate MOS-FETs
Legal information
Data sheet status
[1] Please consult the most recently issued document before initiating or completing a design.
[2] The term ‘short data sheet’ is explained in section “Definitions”.
[3] The product status of device(s) described in this document may have changed since this document was published and may differ in case of multiple devices. The latest product status
information is available on the Internet at URL http://www.nxp.com.
Definitions
Draft — The document is a draft version only. The content is still under
internal review and subject to formal approval, which may result in
modifications or additions. NXP Semiconductors does not give any
representations or warranties as to the accuracy or completeness of
information included herein and shall have no liability for the consequences of
use of such information.
Short data sheet — A short data sheet is an extract from a full data sheet
with the same product type number(s) and title. A short data sheet is intended
for quick reference only and should not be relied upon to contain detailed and
full information. For detailed and full information see the relevant full data
sheet, which is available on request via the local NXP Semiconductors sales
office. In case of any inconsistency or conflict with the short data sheet, the
full data sheet shall prevail.
Disclaimers
General — Information in this document is believed to be accurate and
reliable. However, NXP Semiconductors does not give any representations or
warranties, expressed or implied, as to the accuracy or completeness of such
information and shall have no liability for the consequences of use of such
information.
Right to make changes — NXP Semiconductors reserves the right to make
changes to information published in this document, including without
limitation specifications and product descriptions, at any time and without
notice. This document supersedes and replaces all information supplied prior
to the publication hereof.
Suitability for use — NXP Semiconductors products are not designed,
authorized or warranted to be suitable for use in medical, military, aircraft,
space or life support equipment, nor in applications where failure or
malfunction of an NXP Semiconductors product can reasonably be expected
to result in personal injury, death or severe property or environmental
damage. NXP Semiconductors accepts no liability for inclusion and/or use of
NXP Semiconductors products in such equipment or applications and
therefore such inclusion and/or use is at the customer’s own risk.
Applications — Applications that are described herein for any of these
products are for illustrative purposes only. NXP Semiconductors makes no
representation or warranty that such applications will be suitable for the
specified use without further testing or modification.
Limiting values — Stress above one or more limiting values (as defined in
the Absolute Maximum Ratings System of IEC 60134) may cause permanent
damage to the device. Limiting values are stress ratings only and operation of
the device at these or any other conditions above those given in the
Characteristics sections of this document is not implied. Exposure to limiting
values for extended periods may affect device reliability.
Terms and conditions of sale — NXP Semiconductors products are sold
subject to the general terms and conditions of commercial sale, as published
at http://www.nxp.com/profile/terms, including those pertaining to warranty,
intellectual property rights infringement and limitation of liability, unless
explicitly otherwise agreed to in writing by NXP Semiconductors. In case of
any inconsistency or conflict between information in this document and such
terms and conditions, the latter will prevail.
No offer to sell or license — Nothing in this document may be interpreted
or construed as an offer to sell products that is open for acceptance or the
grant, conveyance or implication of any license under any copyrights, patents
or other industrial or intellectual property rights.
Trademarks
Notice: All referenced brands, product names, service names and trademarks
are the property of their respective owners.
Contact information
For additional information, please visit: http://www.nxp.com
For sales office addresses, send an email to: salesaddresses@nxp.com
Document status[1][2] Product status[3] Definition
Objective [short] data sheet Development This document contains data from the objective specification for product development.
Preliminary [short] data sheet Qualification This document contains data from the preliminary specification.
Product [short] data sheet Production This document contains the product specification.
Rev. 03 - 14 November 2007
8 of 9
NXP Semiconductors BF908; BF908R
Dual-gate MOS-FETs
© NXP B.V. 2007. All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: salesaddresses@nxp.com
Date of release: 14 November 2007
Document identifier: BF908-R_N_3
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in section ‘Legal information’.
Revision history
Revision history
Document ID Release date Data sheet status Change notice Supersedes
BF908-R_N_3 20071114 Product data sheet - BF908-R_2
Modifications: •Fig. 1 and 2 on page 2; Figure note changed
BF908-R_2 19960730 Product specification - BF908R_1
BF908R_1 - - - -
