BLF278 VHF POWER MOSFET DESCRIPTION: The ASI BLF278 is a Dual Common Source N-Channel EnhancementMode MOSFET RF Power Transistor, Designed for 175 MHz, 300 W Transmitter and Amplifier Applications. PACKAGE STYLE .385X.850 4LFG MAXIMUM RATINGS ID 40 A VDSS 125 V VGS ±40 V PDISS 500 W @ TC = 25 C TJ -65 C to +200 C TSTG -65 C to +150 C θJC 0.35 C/W O O O O O 1 & 2 = DRAIN 3 & 4 = GATE 5 = SOURCE O CHARACTERISTICS SYMBOL O TC = 25 C TEST CONDITIONS MINIMUM TYPICAL MAXIMUM UNITS BVDSS ID = 100 mA IDSS VDS = 50 V VGS = 0 V 5.0 mA IGSS VDS = 0 V VGS = 20 V 1.0 µA VGS(th) ID = 100 mA VDS = 10 V 5.0 V VDS(on) ID = 10 A VGS = 10 V 5 V gfs ID = 5.0 A VDS = 10 V Ciss Coss Crss VDS = 50 V VGS = 0 V Gps η VDD = 50 V f = 175 MHz IDQ = 500 mA ψ V 125 1.0 mhos 5.0 f = 1.0 MHz Pout = 300 W VSWR = 5:1 AT ALL PHASE ANGLES 14 50 350 250 15 pF 16 55 dB % NO DEGRADATION IN OUTPUT POWER A D V A N C E D S E M I C O N D U C T O R, I N C. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 1/7 ERROR! REFERENCE SOURCE NOT FOUND. 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. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 2/7 ERROR! REFERENCE SOURCE NOT FOUND. 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. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 3/7 ERROR! REFERENCE SOURCE NOT FOUND. 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. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 4/7 ERROR! REFERENCE SOURCE NOT FOUND. 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. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 5/7 ERROR! REFERENCE SOURCE NOT FOUND. BLF278 505.000 0.98904 177.900 0.09288 24.3178 0.02253 520.000 0.98753 177.826 0.08876 24.1062 0.02288 535.000 0.98584 177.697 0.08378 27.3328 0.02415 550.000 0.99250 177.572 0.08247 29.3983 0.02494 565.000 0.99413 177.257 0.07822 27.2453 0.02571 580.000 0.99245 177.031 0.07467 27.8200 0.02530 595.000 0.98715 176.735 0.07101 32.0492 0.02706 610.000 0.98797 176.550 0.06786 31.2308 0.02796 625.000 0.98881 176.455 0.06254 32.4249 0.02841 640.000 0.98908 176.285 0.06360 36.9496 0.02939 655.000 0.98753 176.016 0.06277 37.0072 0.02935 670.000 0.98643 175.910 0.06004 40.0063 0.03090 685.000 0.98840 175.782 0.06111 37.8170 0.03147 700.000 0.98846 175.800 0.05886 44.3227 0.03158 710.000 0.98530 175.570 0.05697 43.3396 0.03291 ! Unit: BLF278 ! S1E 1+1Die in an AR pkg. ! ! Meas: 110L#24 ! Vds=50Vdc, Idq=400ma, Vgsth=4.10Vdc, wafer=00712-17 ! 95.5649 95.4464 97.1222 96.0530 97.8381 97.2712 96.9025 96.6285 97.4609 97.4627 98.2586 98.6724 99.1738 100.273 100.088 0.98953 0.98714 0.99400 0.99166 0.99387 0.98799 0.98797 0.98858 0.99071 0.98654 0.98868 0.99076 0.98962 0.99068 0.99163 -178.261 -178.215 -178.628 -178.778 -178.902 -179.373 -179.626 -179.785 -179.900 -179.575 -179.929 179.932 179.695 179.587 179.411 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 *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 JFET 17 14 13 BLF278 JF ;D DBODY 14 17 BLF278 DB ;P MODEL BLF278 MOS MODEL BLF278 JF MODEL BLF278 DB ENDS S NMOS NJF D Ma G S B LEVEL1 G S N (VTO =4 KP = 0.9 E-5 LAMBDA = 0.15 RD = 0.065 RS = 0.07) (VTO = 6.8 BETA = 1 LAMBDA =1) (CJO = 1100 P RS = 0.25 VJ = 0.6 M = 0.4 BV = 13) A D V A N C E D S E M I C O N D U C T O R, I N C. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 6/7 ERROR! REFERENCE SOURCE NOT FOUND. BLF278 BIASING ASI RF TRANSISTORS ASI RF Mosfets are enhancement mode devices. In order to cause drain current to flow, positive voltage of about 3 V needs to be applied to the Gate terminal. The higher the gate voltage applied the higher the drain current. The Mosfet transistor drain current will change with temperature. As the temperature goes up, so will the drain current. In order to prevent a runway situation, the gate voltage needs to have negative temperature coefficient. The following circuit describes a means to achieve a –2mv/ °C coefficient at the gate 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. A D V A N C E D S E M I C O N D U C T O R, I N C. 7525 ETHEL AVENUE • NORTH HOLLYWOOD, CA 91605 • (818) 982-1202 • FAX (818) 765-3004 Specifications are subject to change without notice. REV. B 7/7