A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 1/7
Specif i cations are subject to change without notice.
CHARACTERISTICS TC = 25 OC
SYMBOL TEST CONDITIONS MINIMUM TYPICAL MAXIMUM UNITS
BVDSS ID = 100 mA 125 V
IDSS VDS = 50 V VGS = 0 V 5.0 mA
IGSS VDS = 0 V VGS = 20 V 1.0 µ
µµ
µA
VGS(th) ID = 100 mA VDS = 10 V 1.0 5.0 V
VDS(on) ID = 10 A VGS = 10 V 5 V
gfs ID = 5.0 A VDS = 10 V 5.0 mhos
Ciss
Coss
Crss VDS = 50 V VGS = 0 V f = 1.0 MHz 350
250
15
pF
Gps
η
ηη
η VDD = 50 V IDQ = 500 mA Pout = 300 W
f = 175 MHz 14
50 16
55 dB
%
ψ
ψψ
ψ VSWR = 5:1 AT ALL PHASE ANGLES NO DEGRADATION IN OUTPUT POWER
VHF POWER MOSFET
PACKAGE STYLE .385X.850 4LFG
1 & 2 = DRAIN 3 & 4 = GATE
5 = SOURCE
BLF278
DESCRIPTION:
The ASI BLF278 is a Dual Common
Source N-Channel Enhancement -
Mode MOSFET
RF Power Transistor , Designed for
175 MHz, 300 W Tr ansm it t er and
Amplif ier Applications.
MAXIMUM RATINGS
ID 40 A
VDSS 125 V
VGS ±40 V
PDISS 500 W @ TC = 25 OC
TJ -65 OC to +200 OC
TSTG -65 OC to +150 OC
θ
θθ
θJC 0.35 OC/W
A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 2/7
ERROR! REFERENCE SOURCE NOT FOUND.
Specif i cations are subject to change without notice.
BLF278
A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 3/7
ERROR! REFERENCE SOURCE NOT FOUND.
Specif i cations are subject to change without notice.
BLF278
A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 4/7
ERROR! REFERENCE SOURCE NOT FOUND.
Specif i cations are subject to change without notice.
BLF278
A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 5/7
ERROR! REFERENCE SOURCE NOT FOUND.
Specif i cations are subject to change without notice.
BLF278
ASI RF DEVICES
!
! BLF278 (Each side)
!
! S PARAMETERS
!
! VDS=50V, IDQ=400mA
!
# MHZ S MA R 50
! Freq=Mhz Mag[s11] Ang[s11] Mag[s21] Ang[s21] Mag[s12] Ang[s12] Mag[s22] Ang[s22]
10.0000 0.83747 -151.063 27.3956 94.1661 0.01705 8.72886 0.58986 -142.841
15.0000 0.84031 -158.633 18.7280 85.9160 0.01628 -0.96378 0.60251 -150.026
20.0000 0.84723 -162.908 13.8120 79.8023 0.01616 -5.92879 0.62064 -153.163
25.0000 0.85287 -165.197 10.8614 74.7640 0.01559 -12.5836 0.64215 -154.551
30.0000 0.86258 -166.662 8.80371 70.1601 0.01546 -14.0670 0.66315 -155.623
35.0000 0.87300 -167.708 7.31926 66.2638 0.01422 -15.2201 0.68657 -156.454
40.0000 0.87885 -168.313 6.20180 62.4688 0.01355 -21.7797 0.71127 -156.911
45.0000 0.88779 -168.889 5.33086 59.0794 0.01310 -22.1195 0.73435 -157.702
50.0000 0.89448 -169.583 4.62723 55.9900 0.01266 -23.4078 0.75375 -158.189
55.0000 0.90299 -170.078 4.04324 53.3573 0.01120 -24.5177 0.77229 -158.969
60.0000 0.90882 -170.598 3.57797 50.8563 0.01064 -28.1139 0.79081 -159.728
65.0000 0.91539 -170.945 3.17462 48.6080 0.01003 -27.6968 0.80771 -160.420
70.0000 0.92222 -171.452 2.83402 46.2563 0.00986 -29.2237 0.82084 -160.996
75.0000 0.92639 -171.760 2.54871 44.4224 0.00850 -28.0810 0.83260 -161.649
80.0000 0.93150 -171.996 2.30691 42.6712 0.00817 -32.6804 0.85175 -162.239
85.0000 0.93589 -172.523 2.09657 40.9265 0.00775 -31.0442 0.85892 -163.014
90.0000 0.94214 -172.742 1.90687 39.4646 0.00770 -29.1611 0.86738 -163.709
95.0000 0.94487 -173.065 1.74744 38.0245 0.00655 -26.9029 0.87574 -164.155
100.000 0.94613 -173.318 1.60882 36.9997 0.00624 -26.4073 0.88477 -164.816
115.000 0.95430 -174.193 1.27120 33.7465 0.00494 -22.0092 0.90443 -166.111
130.000 0.96370 -174.772 1.03082 31.0149 0.00405 -8.62124 0.91904 -167.411
145.000 0.96577 -175.445 0.85053 28.5008 0.00345 15.2775 0.93060 -168.612
160.000 0.97354 -176.090 0.71706 26.9099 0.00406 18.2489 0.94317 -169.671
175.000 0.97232 -176.684 0.60905 24.9097 0.00396 34.6921 0.94921 -170.411
190.000 0.97373 -176.941 0.52601 23.6811 0.00442 60.9895 0.95349 -171.191
205.000 0.97665 -177.305 0.45427 22.8048 0.00512 67.5609 0.96082 -171.773
220.000 0.98025 -177.663 0.39996 22.0539 0.00648 73.2592 0.96150 -172.405
235.000 0.98177 -178.142 0.35799 21.1790 0.00691 76.8913 0.96810 -172.973
250.000 0.98017 -178.354 0.31865 20.4965 0.00758 81.4188 0.97058 -173.557
265.000 0.98152 -178.702 0.28756 20.6230 0.00858 83.5928 0.97094 -173.979
280.000 0.98349 -178.836 0.26320 19.8483 0.00980 86.7674 0.97233 -174.400
295.000 0.98441 -179.154 0.23858 19.3588 0.01042 86.3890 0.97668 -174.574
310.000 0.98361 -179.471 0.21519 19.1929 0.01098 89.5518 0.97479 -175.077
325.000 0.98561 -179.718 0.19819 18.4377 0.01229 91.7969 0.97746 -175.505
340.000 0.98501 -179.869 0.18099 19.6530 0.01308 92.2737 0.97940 -175.953
355.000 0.98692 179.859 0.16810 18.6449 0.01349 91.3383 0.98188 -175.897
370.000 0.98555 179.752 0.16137 20.5312 0.01418 91.9241 0.98041 -176.189
385.000 0.98822 179.511 0.15027 19.7641 0.01560 92.4536 0.98073 -176.588
400.000 0.98829 179.336 0.13766 20.8798 0.01620 92.0722 0.98261 -176.808
415.000 0.98773 179.166 0.12974 19.0245 0.01724 93.8917 0.98610 -177.114
430.000 0.98886 178.743 0.11997 19.9215 0.01812 94.8087 0.98610 -177.171
445.000 0.98952 178.735 0.11662 19.8737 0.01928 93.0825 0.98659 -177.573
460.000 0.99223 178.652 0.10659 20.2039 0.02015 93.6649 0.98513 -177.605
475.000 0.99217 178.525 0.10291 22.3386 0.02032 93.8780 0.98815 -177.706
490.000 0.99093 178.328 0.09499 23.5854 0.02087 95.3520 0.98734 -178.180
A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 6/7
ERROR! REFERENCE SOURCE NOT FOUND.
Specif i cations are subject to change without notice.
BLF278
505.000 0.98904 177.900 0.09288 24.3178 0.02253 95.5649 0.98953 -178.261
520.000 0.98753 177.826 0.08876 24.1062 0.02288 95.4464 0.98714 -178.215
535.000 0.98584 177.697 0.08378 27.3328 0.02415 97.1222 0.99400 -178.628
550.000 0.99250 177.572 0.08247 29.3983 0.02494 96.0530 0.99166 -178.778
565.000 0.99413 177.257 0.07822 27.2453 0.02571 97.8381 0.99387 -178.902
580.000 0.99245 177.031 0.07467 27.8200 0.02530 97.2712 0.98799 -179.373
595.000 0.98715 176.735 0.07101 32.0492 0.02706 96.9025 0.98797 -179.626
610.000 0.98797 176.550 0.06786 31.2308 0.02796 96.6285 0.98858 -179.785
625.000 0.98881 176.455 0.06254 32.4249 0.02841 97.4609 0.99071 -179.900
640.000 0.98908 176.285 0.06360 36.9496 0.02939 97.4627 0.98654 -179.575
655.000 0.98753 176.016 0.06277 37.0072 0.02935 98.2586 0.98868 -179.929
670.000 0.98643 175.910 0.06004 40.0063 0.03090 98.6724 0.99076 179.932
685.000 0.98840 175.782 0.06111 37.8170 0.03147 99.1738 0.98962 179.695
700.000 0.98846 175.800 0.05886 44.3227 0.03158 100.273 0.99068 179.587
710.000 0.98530 175.570 0.05697 43.3396 0.03291 100.088 0.99163 179.411
! Unit: BLF278
! S1E 1+1Die in an AR pkg.
!
! Meas: 110L#24
! Vds=50Vdc, Idq=400ma, Vgsth=4.10Vdc, wafer=00712-17
!
SPICE MODEL
*HIGH POWER, HIGH FREQUENCY, RF N-CHANNEL VERTICAL DMOS MOSFET
*TO GENERATE S PARAMETER MATCHING DATA SHHET, SET VG = 4.3 V FOR IDQ = 455 Ma
*MODEL APPLICABLE FOR BLF278
*NOTE:- HP/EESOF USES ‘GATE DRAIN SOURCE’ ORDER
* ( ;D G S)
.SUBCKT BLF278/PF 20 10 30
LG 10 11 0.29n
RGATE 11 12 0.73
CG 10 30 0.01P
CRSS 12 17 15.3P
CISS 12 14 490P
LS 14 30 0.2N
CS 14 30 0.02P
LD 17 20 0.1N
CD 20 30 2.9P
R_RC 16 17 2.2
C_RC 14 16 31.2P
MOS 13 12 14 14 BLF278 MOS L = 1.1 U W = 0.778 ;D G S B LEVEL1
JFET 17 14 13 BLF278 JF ;D G S
DBODY 14 17 BLF278 DB ;P N
MODEL BLF278 MOS NMOS (VTO =4 KP = 0.9 E-5 LAMBDA = 0.15 RD = 0.065 RS = 0.07)
MODEL BLF278 JF NJF (VTO = 6.8 BETA = 1 LAMBDA =1)
MODEL BLF278 DB D (CJO = 1100 P RS = 0.25 VJ = 0.6 M = 0.4 BV = 13)
ENDS
S
A D V A N C E D S E M I C O N D U C T O R, I N C. REV. B
7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 7/7
ERROR! REFERENCE SOURCE NOT FOUND.
Specif i cations are subject to change without notice.
BLF278
BIASING ASI RF TRANSISTORS
ASI RF Mosfets are enhancem ent mode devices. In order to cause drain cur rent to flow, positive
voltage of about 3 V needs to be applied to the Ga t e terminal. The higher the gate voltage applied the
higher t he dr ain cur r ent. The Mosfet tr ansistor drain current will change with temper at ur e. As the
temperat ur e goes up, so will the drain current. I n or der to prevent a runway situation, the gat e voltage
needs to have negative temper at ure coefficient . The following circuit describes a means to achieve
a –2mv/ °C coefficient at the g at e terminal.
• The temperature coefficient of a 6.8V zener is about + 2mv/ °C and the diode is about –2mv/ °C
• The gate of a transistor draws no current, so there is no current flow in R4. R4 is used as a RF isolation
resistor.
• R1 is adjusted to cause about 10ma of current flow into the circuit.
• R2 and R3 can be a potentiometer to adjust for the desired gate voltage. The total value of R2 and R3
should be high enough so that the current drawn in R2 and R3 is substantially less than 10ma.
Recommend around 2ma.
