SEMICONDUCTOR TECHNICAL DATA
Order this document
by MRF148/D
The RF MOSFET Line
RF Power Field-Effect Transistor
N–Channel Enhancement–Mode
Designed for power amplifier applications in industrial, commercial and
amateur radio equipment to 175 MHz.
•
Superior High Order IMD
•
Specified 50 Volts, 30 MHz Characteristics
Output Power = 30 Watts
Power Gain = 18 dB (Typ)
Efficiency = 40% (Typ)
•
IMD(d3) (30 W PEP) — – 35 dB (Typ)
•
IMD(d11) (30 W PEP) — – 60 dB (Typ)
•
100% Tested For Load Mismatch At All Phase Angles With
30:1 VSWR
•
Lower Reverse Transfer Capacitance (3.0 pF Typical)
D
MRF148A
30 W, to 175 MHz
N–CHANNEL MOS
LINEAR RF POWER
FET
G
S
CASE 211–07, STYLE 2
MAXIMUM RATINGS
Rating
Drain–Source Voltage
Drain–Gate Voltage
Gate–Source Voltage
Drain Current — Continuous
Total Device Dissipation @ TC = 25°C
Derate above 25°C
Storage Temperature Range
Operating Junction Temperature
Symbol
VDSS
VDGO
VGS
ID
PD
Tstg
TJ
Value
120
120
±
40
6.0
115
0.66
– 65 to +150
200
Unit
Vdc
Vdc
Vdc
Adc
Watts
W/°C
°C
°C
THERMAL CHARACTERISTICS
Characteristic
Thermal Resistance, Junction to Case
Symbol
R
θJC
Max
1.52
Unit
°C/W
NOTE –
CAUTION
– MOS devices are susceptible to damage from electrostatic charge. Reasonable precautions in handling and
packaging MOS devices should be observed.
Replaces MRF148/D
1
ELECTRICAL CHARACTERISTICS
(TC = 25°C unless otherwise noted.)
Characteristic
Symbol
Min
Typ
Max
Unit
OFF CHARACTERISTICS
Drain–Source Breakdown Voltage (VGS = 0, ID = 10 mA)
Zero Gate Voltage Drain Current (VDS = 50 V, VGS = 0)
Gate–Body Leakage Current (VGS = 20 V, VDS = 0)
V(BR)DSS
IDSS
IGSS
125
—
—
—
—
—
—
1.0
100
Vdc
mAdc
nAdc
ON CHARACTERISTICS
Gate Threshold Voltage (VDS = 10 V, ID = 10 mA)
Drain–Source On–Voltage (VGS = 10 V, ID = 2.5 A)
Forward Transconductance (VDS = 10 V, ID = 2.5 A)
VGS(th)
VDS(on)
gfs
1.0
1.0
0.8
2.5
3.0
1.2
5.0
5.0
—
Vdc
Vdc
mhos
DYNAMIC CHARACTERISTICS
Input Capacitance (VDS = 50 V, VGS = 0, f = 1.0 MHz)
Output Capacitance (VDS = 50 V, VGS = 0, f = 1.0 MHz)
Reverse Transfer Capacitance (VDS = 50 V, VGS = 0, f = 1.0 MHz)
Ciss
Coss
Crss
—
—
—
62
35
3.0
—
—
—
pF
pF
pF
FUNCTIONAL TESTS (SSB)
Common Source Amplifier Power Gain
(VDD = 50 V, Pout = 30 W (PEP), IDQ = 100 mA)
Drain Efficiency
(VDD = 50 V, f = 30 MHz, IDQ = 100 mA)
Intermodulation Distortion
(VDD = 50 V, Pout = 30 W (PEP),
f = 30; 30.001 MHz, IDQ = 100 mA)
Load Mismatch
(VDD = 50 V, Pout = 30 W (PEP), f = 30; 30.001 MHz,
IDQ = 100 mA, VSWR 30:1 at all Phase Angles)
(30 MHz)
(175 MHz)
(30 W PEP)
(30 W CW)
Gps
η
—
—
—
—
—
—
18
15
40
50
– 35
– 60
—
—
—
—
—
—
dB
%
dB
IMD(d3)
IMD(d11)
ψ
No Degradation in Output Power
CLASS A PERFORMANCE
Intermodulation Distortion (1) and Power Gain
(VDD = 50 V, Pout = 10 W (PEP), f1 = 30 MHz,
f2 = 30.001 MHz, IDQ = 1.0 A)
GPS
IMD(d3)
IMD(d9 – 13)
—
—
—
20
– 50
– 70
—
—
—
dB
NOTE:
1. To MIL–STD–1311 Version A, Test Method 2204B, Two Tone, Reference Each Tone.
L1
BIAS +
0 – 10 V –
C1
R1
DUT
T2
RF
INPUT
T1
R3
C8
R2
C2
RF
OUTPUT
C4
C5
L2
+
C6
+
C7
–
50 V
C3
R4
R1, R2 — 200
Ω,
1/2 W Carbon
R3 — 4.7
Ω,
1/2 W Carbon
R4 — 470
Ω,
1.0 W Carbon
T1 — 4:1 Impedance Transformer
T2 — 1:2 Impedance Transformer
C1, C2, C3, C4, C5, C6 — 0.1
µF
Ceramic Chip or Equivalent
C7 — 10
µF,
100 V Electrolytic
C8 — 100 pF Dipped Mica
L1 — VK200 20/4B Ferrite Choke or Equivalent (3.0
µH)
L2 — Ferrite Bead(s), 2.0
µH
Figure 1. 2.0 to 50 MHz Broadband Test Circuit
Replaces MRF148/D
2
25
Pout , OUTPUT POWER (WATTS)
60
VDD = 50 V
40 V
IDQ = 100 mA
0
60
30 MHz
IDQ = 100 mA
1
1.5
2
2.5
Pin, INPUT POWER (WATTS)
VDS = 30 V
VDS = 15 V
4
+ 50 Vdc
+
C5
C7
L1
C6
C1
T1
RF OUTPUT
50
Ω
12.5
Ω
T1 — 4:1 Impedance Ratio
T1 —
Transformer, Line
T1 —
Impedance = 25
Ω
40
20
VDD = 50 V
40 V
150 MHz
40
20
20
POWER GAIN (dB)
15
10
VDD = 50 V
IDQ = 100 mA
Pout = 30 W (PEP)
5
0
2
5
10
20
50
100
200
0
0
0.5
f, FREQUENCY (MHz)
Figure 2. Power Gain versus Frequency
– 30
d3
– 40
d5
– 50
VDD = 50 V, IDQ = 100 mA, TONE SEPARATION 1 kHz
– 30
– 40
d3
d5
10
20
30
Pout, OUTPUT POWER (WATTS PEP)
40
30 MHz
150 MHz
2000
f T, UNITY GAIN FREQUENCY (MHz)
Figure 3. Output Power versus Input Power
IMD, INTERMODULATION DISTORTION (dB)
1000
– 50
0
0
0
1
2
3
ID, DRAIN CURRENT (AMPS)
Figure 4. IMD versus Pout
Figure 5. Common Source Unity Gain Frequency
versus Drain Current
+ BIAS
0–6 V
C3
C2
R2
RFC1
C4
L2
DUT
RF INPUT
R1
C1 — 91 pF Unelco Type MCM 01/010
C2, C4 — 0.1
µF
Erie Red Cap
C3 — Allen Bradley 680 pF Feed Thru
C5 — 1.0
µF,
50 Vdc Electrolytic
C6 — 15 pF Unelco Type J101
C7 — 24 pF Unelco Type MCM 01/010
L1 — 2 Turns #18 AWG, 5/16″ ID
L2 — 4 Turns #18 AWG, 5/16″ ID
R1 — 1.0 Ohm, 1/4 W Carbon
R2 — 2000 Ohm, 1/4 W Carbon
RFC1 — VK200 21/4B
T1 — 4:1 Transformer, 1.75″ Subminiature
T1 —
Coaxial Cable
Figure 6. 150 MHz Test Circuit
Replaces MRF148/D
3
2
I DS , DRAIN CURRENT (AMPS)
I D , DRAIN CURRENT (AMPS)
10
7
5
3
2
TC = 25°C
1
0.7
0.5
0.3
0.2
1
VDS = 10 V
gfs = 1.2 mho
0
0
1
2
3
4
5
6
7
8
VGS, GATE–SOURCE VOLTAGE (VOLTS)
9
10
0.1
0.2
0.4
0.7 1
2
4
7 10
20
40
VDS, DRAIN–SOURCE VOLTAGE (VOLTS)
70 100 200
Figure 7. Gate Voltage versus Drain Current
Figure 8. DC Safe Operating Area (SOA)
175
150
50
30
15
7.0
4.0
f = 2.0 MHz
ZOL* = Conjugate of the optimum load impedance
ZOL* =
into which the device output operates at a
ZOL* =
given output power, voltage and frequency.
175
ZOL*
f = 2.0 MHz
Zin
VDD = 50 V
IDQ = 100 mA
Pout = 30 W PEP
Gate Shunted By 100
Ω
Figure 9. Impedance Coordinates — 50 Ohm
Characteristic Impedance
Replaces MRF148/D
4
RF POWER MOSFET CONSIDERATIONS
MOSFET CAPACITANCES
The physical structure of a MOSFET results in capacitors
between the terminals. The metal oxide gate structure
determines the capacitors from gate–to–drain (Cgd), and
gate–to–source (Cgs). The PN junction formed during the
fabrication of the RF MOSFET results in a junction capaci-
tance from drain–to–source (Cds).
These capacitances are characterized as input (Ciss),
output (Coss) and reverse transfer (Crss) capacitances on data
sheets. The relationships between the inter–terminal capaci-
tances and those given on data sheets are shown below. The
Ciss can be specified in two ways:
1. Drain shorted to source and positive voltage at the gate.
2. Positive voltage of the drain in respect to source and zero
volts at the gate. In the latter case the numbers are lower.
However, neither method represents the actual operat-
ing conditions in RF applications.
Since this test is performed at a fast sweep speed, heating of
the device does not occur. Thus, in normal use, the higher
temperatures may degrade these characteristics to some
extent.
DRAIN CHARACTERISTICS
One figure of merit for a FET is its static resistance in the
full–on condition. This on–resistance, VDS(on), occurs in the
linear region of the output characteristic and is specified under
specific test conditions for gate–source voltage and drain
current. For MOSFETs, VDS(on) has a positive temperature
coefficient and constitutes an important design consideration
at high temperatures, because it contributes to the power
dissipation within the device.
GATE CHARACTERISTICS
The gate of the RF MOSFET is a polysilicon material, and
is electrically isolated from the source by a layer of oxide. The
input resistance is very high — on the order of 109 ohms —
resulting in a leakage current of a few nanoamperes.
Gate control is achieved by applying a positive voltage
slightly in excess of the gate–to–source threshold voltage,
VGS(th).
Gate Voltage Rating
— Never exceed the gate voltage
rating. Exceeding the rated VGS can result in permanent
damage to the oxide layer in the gate region.
Gate Termination
— The gates of these devices are
essentially capacitors. Circuits that leave the gate open–cir-
cuited or floating should be avoided. These conditions can
result in turn–on of the devices due to voltage build–up on the
input capacitor due to leakage currents or pickup.
Gate Protection
— These devices do not have an internal
monolithic zener diode from gate–to–source. If gate protection
is required, an external zener diode is recommended.
DRAIN
Cgd
GATE
Cds
Cgs
Ciss = Cgd + Cgs
Coss = Cgd + Cds
Crss = Cgd
SOURCE
LINEARITY AND GAIN CHARACTERISTICS
In addition to the typical IMD and power gain data
presented, Figure 5 may give the designer additional informa-
tion on the capabilities of this device. The graph represents the
small signal unity current gain frequency at a given drain
current level. This is equivalent to fT for bipolar transistors.
EQUIVALENT TRANSISTOR PARAMETER TERMINOLOGY
Collector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Emitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V(BR)CES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VCBO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IEBO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VBE(on) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VCE(sat) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cib . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cob . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
hfe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RCE(sat) =
Drain
Source
Gate
V(BR)DSS
VDGO
ID
IDSS
IGSS
VGS(th)
VDS(on)
Ciss
Coss
gfs
VDS(on)
VCE(sat) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r
DS(on) =
ID
IC
Replaces MRF148/D
5
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