BLF278 ASI | Alldatasheet
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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
Specifications 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 V GS = 0 V 5.0 mA IGSS VDS = 0 V V GS = 20 V 1.0 µµµµA VGS(th) ID = 100 mA V DS = 10 V 1.0 5.0 V VDS(on) ID = 10 A V GS = 10 V 5 V gfs ID = 5.0 A V DS = 10 V 5.0 mhos Ciss Coss Crss VDS = 50 V V GS = 0 V f = 1.0 MHz 350 250 pF Gps ηηηη VDD = 50 V I DQ = 500 mA Pout = 300 W f = 175 MHz dB ψψψψ 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 Transmitter and
Amplifier Applications. MAXIMUM RATINGS ID 40 A VDSS 125 V VGS ±40 V PDISS 500 W @ TC = 25 O C TJ -65 O C to +200 O C TSTG -65 O C to +150 O C θθθθJC 0.35 O C/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. Specifications 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. Specifications 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. Specifications 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. Specifications 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]
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. Specifications are subject to change without notice. BLF278 ! 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. Specifications are subject to change without notice. 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.