1
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
Product Image
Designed primarily for lin ear large signal output stages
to 80 MHz.
Specified 50 volts, 30 MHz characteristics
Output power = 600 watts
Power gain = 21 dB (typ.)
Efficiency = 45% (t yp.)
2
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
3
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
4
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
5
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
6
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
7
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
RF POWER MOSFET CONSIDERATIONS
MOSFET CAPACITANCES
The physical structure of a MOSFET results in capacitors
between the terminals. The metal oxide gate structure de-
termines 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
capacitances and those given on data sheets are shown
below. The
Ciss can be specified in t wo 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 operating conditions in RF applications.
LINEARITY AND GAIN CHARACTERISTICS
In addition to the typical IMD and power gain data pre-
sented, Figure 5 may give the designer additional informa-
tion on the capabilities of this devic e. The graph represents
the small signal unity current gain frequency at a given
drain current level. This is equivalent to fT for bipolar tran-
sistors. Since this test is performed at a fast sweep speed,
heating of the device does not occur. Thus, in normal use,
the higher temperatures ma y 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 tem-
perature 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 polysilico n 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 i n the gate region.
Gate Termination — The gates of these devices are es-
sentially capacitors. Circuits that leave the gate open–
circuited or floating should be avoided. These conditions
can result in turn–on of the d evices due to vo ltage build–u p
on the input capacitor due to leakage curr ents or pickup.
Gate Protection — These devices do not have an inte rnal
monolithic zener diode from gate–to–s ource. If gate protec-
tion is required, an external zener diode is recommended.
IMPEDANCE CHARACTERISTICS
Device input and output impedances are normally ob-
tained by measuring their conjugates in an optimized nar-
row band test circuit. These test circuits are designed and
constructed for a number of fr equency points dependin g on
the frequency coverage of characterization. For low fre-
quencies the circuits consist of standard LC matching net-
works including variable capacitors for peak tuning. At in-
creasing power levels the output impedance decreases,
resulting in higher RF currents in the matching network.
This makes the practicality of output impedance measure-
ments in the manner described questionable at power lev-
els higher than 200–300 W for devices operated at 50 V
and 150–200 W for devices operated at 28 V. The physical
sizes and values required for the components to withstand
the RF currents increase to a point where physical con-
struction of the output matching network gets difficult if not
impossible. For this reason the output impedances are not
given for high power devices such as the MRF154 and
MRF157.
However, formulas like for a single ended
design or
for a push–pull design can be
used to obtain reasonably close approximations to actual
values.
8
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
MOUNTING OF HIGH POWER RF
POWER TRANSISTORS
The package of this device is designed for conduction
cooling. It is extremely important to minimize the thermal
resistance between the devic e flange and the heat dissip a-
tor.
Since the device mounting flange is made of soft copper,
itmay be deformed during various stages of handling or
during transportation. It is recommended that the user
makes a final inspection on this before the device installa-
tion. ±0.0005, is considered sufficient for the flange bottom.
The same applies to the heat dissipator in the device
mounting area. If copper heat sink is not used, a copper
head spreader is strongly recommended between the de-
vice mounting surfaces and the main heat sink. It should be
at least 1/4, thick and extend at least one inch from the
flange edges. A thin layer of thermal compound in al l inter-
faces is, of course, essential. The recommended torque on
the 4–40 mounting screws should be in the area of 4–5
lbs.–inch, and spring type lock washers along with flat
washers are recommended.
For die temperature calculations, the Δ temperature from a
corner mounting screw area to the bottom center of the
flange is approximatel y 5°C a nd 10°C under normal oper at-
ing conditions (dissipation 15 0 W and 300 W respectively).
The main heat dissipater must be sufficiently large and
have low Rθ for moderate air velocit y, unless liquid cooling
is employed.
CIRCUIT CONSIDERATIONS
At high power levels (500 W and up), the circuit layout
becomes critical due to the low impedance levels and high
RF currents associated with the output matching. Some of
the components, such as capacitors and inductors must
also withstand these currents. The component losses are
directly proportional to the op erating frequency. The manu-
facturers
specifications on capacitor ratings should be consulted on
these aspects prior to design.
Push–pull circuits are less critical in general, since the
ground referenced RF loops are practically eliminated, and
the impedance levels are higher for a given power output.
High power broadband transformers are also easier to de-
sign than comparable LC matching networks.
9
Linear RF Power MOSFET
600W, to 80MHz M/A-COM Products
Released - Rev. 07.07
MRF157
North America Tel: 800.366.2266 / Fax: 978.366.2266
Europe Tel: 44.1908.574.200 / Fax: 44.1908.574.300
Asia/Pacific Tel: 81.44.844.8296 / Fax: 81.44.844.8298
Visit www.macomtech.com for additional data sheets and prod uct information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.