MGA-82563-TR1 View Datasheet(PDF) - HP => Agilent Technologies
Part Name
Description
Manufacturer
MGA-82563-TR1 Datasheet PDF : 12 Pages
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22
20
Power
18
16
14
Gain
12
10
8
6
4
NF
2
0
0
1
2
3
4
SUPPLY VOLTAGE (V)
Figure19. Gain,NoiseFigure,and
Output Power vs. Supply Voltage.
There are several means of biasing
the MGA-82563 at 3 volts in
systems that use higher power
supply voltages. The simplest
method, shown in Figure 20a, is to
use a series resistor to drop the
device voltage to 3 volts. For
example, a 24 Ω resistor will drop
a 5-volt supply to 3 volts at the
nominal current of 84 mA. Some
variation in performance could be
expected for this method due to
variations in current within the
specified 63 to 101 mA min/max
range.
+5 V
+5 V
+5 V
24 Ω Silicon
Diodes
Zener
Diode
(a)
(b)
(c)
Figure 20. Biasing From Higher
Supply Voltages.
A second method illustrated in
Figure 20b, is to use forward-
biased diodes in series with the
power supply. For example, three
silicon diodes connected in series
will drop a 5-volt supply to
approximately 3 volts.
The use of the series diode
approach has the advantage of
less dependency on current
variation in the amplifiers since
the forward voltage drop of a
diode is somewhat current
independent.
Reverse breakdown diodes (e.g.,
Zener diodes) could also be used
as in Figure 20c. However, care
should be taken to ensure that the
noise generated by diodes in
either Zener or reverse break-
down is adequately filtered (e.g.,
bypassed to ground) such that the
diode’s noise is not added to the
amplifier’s signal.
Note that the voltage-dropping
component in each of these three
methods must be able to safely
dissipate up to 200 mW.
Thermal Design
Considerations
Good thermal design is important
in the application of medium
power devices, especially when
housed in miniature packages
such as the SOT-363/SC-70.
As previously mentioned in the
“RF Layout” section, the use of
multiple vias near all of the
ground pins provides an important
part of the heatsinking function.
For reliable operation, the channel
temperature should be kept within
the 165° C indicated in the “Abso-
lute Maximum Ratings” table.
As an illustration of a thermal
calculation, consider the example
of a MGA-82563 biased at 3.0 volts
for an application with a MTTF
goal of 106 hours (114 years).
Operating life tests have estab-
lished a MTTF in excess of
106␣ hours (114 years) for a chan-
nel temperature of 150° C. The
maximum device current specifi-
cation is 101 mA at 3 volts. From
Figure 8, it can be seen that the
current will increase by approxi-
mately 9 mA to 110 mA at an
elevated temperature. The device
power dissipation is then:
Pd = 3.0 volts * 110 mA,
which is equal to 330 mW. The
channel-to-“case” thermal resis-
tance (θch-c) from the “Absolute
Maximum Ratings” table is
180°␣ C/watt. Note that “case” is
defined as the interface between
the SOT-363 package pins and the
mounting surface (i.e., PCB).
The temperature rise from the
mounting surface to the MMIC
channel is:
∆T = 0.330 watt * 180° C/watt,
or 59° C. To achieve the MTTF
goal of 106 hours, the circuit to
which the device is mounted
should not exceed:
Tcase = 150° - 59° C,
which is equal to 91° C.
For other MTTF goals and/or
operating temperatures, Hewlett-
Packard publishes reliability data
sheets based on operating life
tests to enable designers to arrive
at a thermal design for their
particular operating environment.
For a reliability data sheet cover-
ing the MGA-82563, request
Hewlett-Packard publication
number 5964-4128E, titled “GaAs
MMIC Amplifier Reliability Data.”
(This reliability data sheet covers
the MGA-82563 as part of this
family of GaAs MMICs.)
6-216
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