SEMICONDUCTOR TECHNICAL DATA
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by MRF173CQ/D
The RF MOSFET Line
RF Power
Field Effect Transistor
N–Channel Enhancement Mode MOSFET
Designed for broadband commercial and military applications up to 200 MHz
frequency range. The high–power, high–gain and broadband performance of
this device makes possible solid state transmitters for FM broadcast or TV
channel frequency bands.
•
Guaranteed Performance at 150 MHz, 28 V:
Output Power = 80 W
Gain = 11 dB (13 dB Typ)
Efficiency = 55% Min. (60% Typ)
•
Low Thermal Resistance
•
Ruggedness Tested at Rated Output Power
•
Nitride Passivated Die for Enhanced Reliability
•
Low Noise Figure — 1.5 dB Typ at 2.0 A, 150 MHz
•
Excellent Thermal Stability; Suited for Class A Operation
MAXIMUM RATINGS
Rating
Drain–Source Voltage
Drain–Gate Voltage
Gate–Source Voltage
Drain Current — Continuous
Total Device Dissipation @ T
C
= 25°C
Derate above 25°C
Storage Temperature Range
Operating Temperature Range
Symbol
V
DSS
V
DGO
V
GS
I
D
P
D
T
stg
T
J
Value
65
65
±40
9.0
220
1.26
–65 to +150
200
Unit
Vdc
Vdc
Vdc
Adc
Watts
W/°C
°C
°C
G
S
D
MRF173CQ
80 W, 28 V, 175 MHz
N–CHANNEL
BROADBAND
RF POWER MOSFET
CASE 316–01, STYLE 2
THERMAL CHARACTERISTICS
Characteristic
Thermal Resistance, Junction to Case
Symbol
R
θJC
Max
0.8
Unit
°C/W
ELECTRICAL CHARACTERISTICS
(T
C
= 25°C unless otherwise noted)
Characteristic
Symbol
Min
Typ
Max
Unit
OFF CHARACTERISTICS
Drain–Source Breakdown Voltage (V
DS
= 0 V, V
GS
= 0 V) I
D
= 50 mA
Zero Gate Voltage Drain Current (V
DS
= 28 V, V
GS
= 0 V)
Gate–Source Leakage Current (V
GS
= 40 V, V
DS
= 0 V)
V
(BR)DSS
I
DSS
I
GSS
65
—
—
—
—
—
—
2.0
1.0
V
mA
µA
ON CHARACTERISTICS
Gate Threshold Voltage (V
DS
= 10 V, I
D
= 50 mA)
Drain–Source On–Voltage (V
DS(on)
, V
GS
= 10 V, I
D
= 3.0 A)
Forward Transconductance (V
DS
= 10 V, I
D
= 2.0 A)
V
GS(th)
V
DS(on)
g
fs
1.0
—
1.8
3.0
—
2.2
6.0
1.4
—
V
V
mhos
(continued)
NOTE —
CAUTION
— MOS devices are susceptible to damage from electrostatic charge. Reasonable precautions in handling and
packaging MOS devices should be observed.
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1
ELECTRICAL CHARACTERISTICS — continued
(T
C
= 25°C unless otherwise noted)
Characteristic
Symbol
Min
Typ
Max
Unit
DYNAMIC CHARACTERISTICS
Input Capacitance (V
DS
= 28 V, V
GS
= 0 V, f = 1.0 MHz)
Output Capacitance (V
DS
= 28 V, V
GS
= 0 V, f = 1.0 MHz)
Reverse Transfer Capacitance (V
DS
= 28 V, V
GS
= 0 V, f = 1.0 MHz)
C
iss
C
oss
C
rss
—
—
—
110
105
10
—
—
—
pF
pF
pF
FUNCTIONAL CHARACTERISTICS
Noise Figure (V
DD
= 28 V, f = 150 MHz, I
DQ
= 50 mA)
Common Source Power Gain
(V
DD
= 28 V, P
out
= 80 W, f = 150 MHz, I
DQ
= 50 mA)
Drain Efficiency (V
DD
= 28 V, P
out
= 80 W, f = 150 MHz, I
DQ
= 50 mA)
Electrical Ruggedness
(V
DD
= 28 V, P
out
= 80 W, f = 150 MHz, I
DQ
= 50 mA)
Load VSWR 30:1 at all phase angles
Series Equivalent Input Impedance
(V
DD
= 28 V, P
out
= 80 W, f = 150 MHz, I
DQ
= 50 mA)
Series Equivalent Output Impedance
(V
DD
= 28 V, P
out
= 80 W, f = 150 MHz, I
DQ
= 50 mA)
NF
G
ps
η
ψ
—
11
55
1.5
13
60
—
—
—
dB
dB
%
No Degradation in Output Power
Z
in
Z
out
—
—
1.35–j5.15
2.72–j149
—
—
Ohms
Ohms
R2
R1
C8
+
-
C11
C10
RFC2
D.U.T.
RFC1
C12
+
-
V
DD
= 28 V
C13
C14
V
dc
+
-
C9
Z1
RF
INPUT C1
C2
C16
L1
C3
L2
R3
L3
C4
C5
L4
C15 C6
C7
RF
OUTPUT
C1, C15 — 470 pF Unelco
C2, C3, C5 — 9–180 pF, Arco 463
C4, C6 — 15 pF, Unelco
C7 — 5–80 pF, Arco 462
C8, C10, C14, C16 — 0.1
µF
C9, C13 — 50
µF,
50 Vdc
C11, C12 — 680 pF, Feed Through
L1 — #16 AWG, 1–1/4 Turns, 0.3″ ID
L2 — #16 AWG Hairpin 1″ long
L3 — #14 AWG Hairpin 0.8″ long
L4 — #14 AWG Hairpin 1.1″ long
RFC1 — Ferroxcube VK200–19/4B
RFC2 — 18 Turns #18 AWG Enameled, 0.3″ ID
R1 — 10 kΩ, 10 Turns Bourns
R2 — 1.8 kΩ, 1/4 W
R3 — 10 kΩ, 1/2 W
Z1 — 1N5925A Motorola Zener
Figure 1. 150 MHz Test Circuit
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TYPICAL CHARACTERISTICS
120
f = 100 MHz
Pout , OUTPUT POWER (WATTS)
100
80
60
40
20
0
0
1
2
3
4
5
6
7
150 MHz
200 MHz
80
70
Pout , OUTPUT POWER (WATTS)
60
50
40
30
f = 100 MHz
150 MHz
200 MHz
V
DD
= 28 V
I
DQ
= 50 mA
20
V
DD
= 13.5 V
I
DQ
= 50 mA
0
2.0
4.0
6.0
8.0
10
12
14
P
in
, INPUT POWER (WATTS)
10
0
8
9
10
P
in
, INPUT POWER (WATTS)
Figure 2. Output Power versus Input Power
Figure 3. Output Power versus Input Power
140
Pout , OUTPUT POWER (WATTS)
120
100
80
60
40
20
0
10
12
14
16
18
20
22
24
26
28
30
1.0 W
I
DQ
= 50 mA
f = 100 MHz
P
in
= 4.0 W
3.0 W
2.0 W
140
Pout , OUTPUT POWER (WATTS)
120
100
80
60
40
20
0
10
12
14
16
18
20
22
24
26
28
30
2.0 W
I
DQ
= 50 mA
f = 150 MHz
P
in
= 8.0 W
6.0 W
4.0 W
V
DD
, SUPPLY VOLTAGE (VOLTS)
V
DD
, SUPPLY VOLTAGE (VOLTS)
Figure 4. Output Power versus Supply Voltage
Figure 5. Output Power versus Supply Voltage
140
Pout , OUTPUT POWER (WATTS)
P
in
= 14 W
10 W
G PS , POWER GAIN (dB)
120
100
80
60
40
20
0
10
12
14
16
18
20
22
24
26
28
30
6.0 W
4.0 W
I
DQ
= 50 mA
f = 200 MHz
22
20
18
16
14
12
10
8.0
6.0
4.0
2.0
20
40
60
80
100 120 140 160
f, FREQUENCY (MHz)
180
200
220
P
out
= 80 W
V
DD
= 28 V
I
DQ
= 50 mA
V
DD
, SUPPLY VOLTAGE (VOLTS)
Figure 6. Output Power versus Supply Voltage
Figure 7. Power Gain versus Frequency
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80
Pout , OUTPUT POWER (WATTS)
70
60
50
40
30
20
10
0
-14
-12
-10 -8.0 -6.0 -4.0 -2.0
0
2.0
V
GS
, GATE-SOURCE VOLTAGE (VOLTS)
4.0
6.0
f = 150 MHz
P
in
= CONSTANT
V
DS
= 28 V
I
DQ
= 50 mA
V
GS(th)
= 3.0 V
6.0
5.0
4.0
3.0
2.0
1.0
0
0
1.0
2.0
3.0
4.0
5.0
V
GS
, GATE-SOURCE VOLTAGE (VOLTS)
6.0
V
DS
= 10 V
V
GS(th)
= 3.0 V
Figure 8. Output Power versus Gate Voltage
ID , DRAIN CURRENT (AMPS)
Figure 9. Drain Current versus Gate Voltage
VGS , GATE SOURCE VOLTAGE (NORMALIZED)
1.2
V
DS
= 28 V
420
360
C oss, CAPACITANCE (pF)
300
240
180
C
iss
140
120
100
80
60
Crss , C iss, CAPACITANCE (pF)
1.1
1.0
0.9
I
D
= 3.0 A
1.0 A
500 mA
50 mA
V
GS
= 0 V
FREQ = 1 MHz
120
60
C
rss
C
oss
40
20
28
0
0.8
0.7
-25
0
25
50
75
100
125
150
175
0
0
4
T
C
, CASE TEMPERATURE (C°)
8
12
16
20
24
V
DS
, DRAIN-SOURCE VOLTAGE (VOLTS)
Figure 10. Gate–Source Voltage versus
Case Temperature
Figure 11. Capacitance versus Drain Voltage
10
ID , DRAIN CURRENT (AMPS)
5.0
2.0
1.0
0.5
0.2
0.1
1.0
2.0
4.0 6.0
10
20
40
V
DS
, DRAIN-SOURCE VOLTAGE (VOLTS)
60
100
T
C
= 25°C
Figure 12. DC Safe Operating Area
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DESIGN CONSIDERATIONS
The MRF173CQ is a RF MOSFET power N–channel en-
hancement mode field–effect transistor (FET) designed for
VHF power amplifier applications. M/A-COM's RF MOSFETs
feature a vertical structure with a planar design, thus avoid-
ing the processing difficulties associated with V–groove pow-
er FETs.
M/A-COM Application Note AN211A, FETs in Theory and
Practice, is suggested reading for those not familiar with the
construction and characteristics of FETs.
The major advantages of RF power FETs include high
gain, low noise, simple bias systems, relative immunity from
thermal runaway, and the ability to withstand severely mis-
matched loads without suffering damage. Power output can
be varied over a wide range with a low power dc control sig-
nal, thus facilitating manual gain control, ALC and modula-
tion.
DC BIAS
The MRF173CQ is an enhancement mode FET and,
therefore, does not conduct when drain voltage is ap-
plied. Drain current flows when a positive voltage is ap-
plied to the gate. See Figure 9 for a typical plot of drain
current versus gate voltage. RF power FETs require for-
ward bias for optimum performance. The value of quies-
cent drain current (I
DQ
) is not critical for many
applications. The MRF173CQ was characterized at I
DQ
=
50 mA, which is the suggested minimum value of I
DQ
. For
special applications such as linear amplification, I
DQ
may
have to be selected to optimize the critical parameters.
The gate is a dc open circuit and draws no current. There-
fore, the gate bias circuit may generally be just a simple re-
sistive divider network. Some special applications may
require a more elaborate bias system.
GAIN CONTROL
Power output of the MRF173CQ may be controlled from its
rated value down to zero (negative gain) by varying the dc
gate voltage. This feature facilitates the design of manual gain
control, AGC/ALC and modulation systems. (see Figure 8.)
AMPLIFIER DESIGN
Impedance matching networks similar to those used with
bipolar VHF transistors are suitable for MRF173CQ. See
M/A-COM Application Note AN721, Impedance Matching
Networks Applied to RF Power Transistors. The higher input
impedance of RF MOSFETs helps ease the task of broad-
band network design. Both small–signal scattering parame-
ters and large–signal impedances are provided. While the
s–parameters will not produce an exact design solution for
high power operation, they do yield a good first approxima-
tion. This is an additional advantage of RF MOS power FETs.
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