RF Input
Figure13. RFLayout.
Standard statistics tables or
calculations provide the probabil-
ity of a parameter falling between
any two values, usually symmetri-
cally located about the mean.
Referring to Figure 12 for ex-
ample, the probability of a param-
eter being between
±
1σ is 68.3%;
between
±
2σ is 95.4%; and be-
tween
±
3σ is 99.7%.
It is recommended that the PCB
pads for the ground pins
not
be
connected together underneath
the body of the package. PCB
traces hidden under the package
cannot be adequately inspected
for SMT solder quality.
PCB Material
FR-4 or G-10 printed circuit board
materials are a good choice for
most low cost wireless applica-
tions. Typical board thickness is
0.020 to 0.031 inches. The width of
the 50
Ω
microstriplines on PC
boards in this thickness range is
also very convenient for mounting
chip components such as the
series inductor at the input or DC
blocking and bypass capacitors.
For higher frequencies or for
noise figure critical applications,
the additional cost of PTFE/glass
dielectric materials may be
warranted to minimize transmis-
sion line loss at the amplifier’s
input. A 0.5 inch length of 50
Ω
microstripline on FR-4, for
example, has approximately
0.3 dB loss at 4 GHz. This loss will
add directly to the noise figure of
the MGA-81563.
68%
95%
99%
-3σ
-2σ
-1σ Mean (µ) +1σ +2σ
(typical)
Parameter Value
+3σ
Figure12. NormalDistribution.
RF Layout
The RF layout in Figure 13 is
suggested as a starting point for
microstripline designs using the
MGA-81563 amplifier. Adequate
grounding is needed to obtain
optimum performance and to
maintain stability. All of the
ground pins of the MMIC should
be connected to the RF
groundplane on the backside of
the PCB by means of plated
6-201
81
To assist designers in optimizing
not only the immediate circuit
using the MGA-81563, but to also
optimize and evaluate trade-offs
that affect a complete wireless
system, the
standard
deviation
(
σ)
is provided for
many of the Electrical Specifica-
tions parameters (at 25°) in
addition to the mean. The stan-
dard deviation is a measure of the
variability about the mean. It will
be recalled that a normal distribu-
tion is completely described by
the mean and standard deviation.
through holes (vias) that are
placed near the package termi-
nals. As a minimum, one via
should be located next to each
ground pin to ensure good RF
grounding. It is a good practice to
use multiple vias to further
minimize ground path inductance.
50
Ω
RF Output
and V
d
50
Ω
Biasing
The MGA-81563 is a voltage-
biased device and is designed to
operate from a single, +3 volt
power supply with a typical
current drain of 42 mA. The
internal current regulation circuit
allows the amplifier to be oper-
ated with voltages as high +5 volts
or as low as +1.5 volt. Refer to the
section titled “Operation at Bias
Voltages Other than 3 Volts” for
information on performance and
precautions when using other
voltages.
Typical Application Example
The printed circuit layout in
Figure 14 can serve as a design
guide. This layout is a
microstripline design (solid
groundplane on the backside of
the circuit board) with a 50
Ω
input and output. The circuit is
fabricated on 0.031-inch thick
FR-4 dielectric material. Plated
through holes (vias) are used to
bring the ground to the top side of
the circuit where needed. Multiple
vias are used to reduce the
inductance of the paths to ground.
H
OUT
IN
+V
MGA-8-A
Figure14. PCBLayout.
A schematic diagram of the
application circuit is shown in
Figure 15. DC blocking capacitors
(C1 and C2) are used at the input
and output of the MMIC to isolate
the device from adjacent circuits.
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
