MRF176GU_15 Datasheet, PDF (11/12 Pages) M/A-COM Technology Solutions, Inc. – The RF MOSFET Line

MRF176GU
MRF176GV
The RF MOSFET Line
200/150W, 500MHz, 50V
in antistatic bags or conductive foam. Upon removal from the
packaging, careful handling procedures should be adhered
to. Those handling the devices should wear grounding
straps and devices not in the antistatic packaging should be
kept in metal tote bins. MOSFETs should be handled by the
case and not by the leads, and when testing the device, all
leads should make good electrical contact before voltage is
applied. As a final note, when placing the FET into the sys-
tem it is designed for, soldering should be done with
grounded equipment.
The gate of the power MOSFET could still be in danger
after the device is placed in the intended circuit. If the gate
may see voltage transients which exceed VGS(max), the cir-
cuit designer should place a 40 V zener across the gate and
source terminals to clamp any potentially destructive spikes.
Using a resistor to keep the gate–to–source impedance low
also helps damp transients and serves another important
function. Voltage transients on the drain can be coupled to
the gate through the parasitic gate–drain capacitance. If the
gate–to–source impedance and the rate of voltage change
on the drain are both high, then the signal coupled to the
gate may be large enough to exceed the gate–threshold
voltage and turn the device on.
DESIGN CONSIDERATIONS
The MRF176G is a RF power N–channel enhancement
mode field–effect transistor (FETs) designed for HF, VHF
andUHF power amplifier applications. M/A-COM RF MOS-
M/A-COM Products
Released - Rev. 07.07
FETs feature a vertical structure with a planar design. M/A-
COM Application Note AN211A, FETs in Theory and Prac-
tice, is suggested reading for those not familiar with the con-
struction 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.
DC BIAS
The MRF176G is an enhancement mode FET and, there-
fore, does not conduct when drain voltage is applied. Drain
current flows when a positive voltage is applied to the gate.
RF power FETs require forward bias for optimum perform-
ance. The value of quiescent drain current (IDQ) is not critical
for many applications. The MRF176G was characterized at
IDQ = 100 mA, each side, which is the suggested minimum-
value of IDQ. For special applications such as linear amplifi-
cation, IDQ may have to be selected to optimize the critical
parameters. The gate is a dc open circuit and draws no cur-
rent. Therefore, the gate bias circuit may be just a simple
resistive divider network. Some applications may require a
more elaborate bias system.
GAIN CONTROL
Power output of the MRF176G may be controlled from its
rated value down to zero (negative gain) by varying the dc
11
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and/or prototype measurements. Commitment to develop is not guaranteed.
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typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available. _{M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make}
Commitment to produce in volume is not guaranteed.
changes to the product(s) or information contained herein without notice.