mga-87563 Avago Technologies, mga-87563 Datasheet - Page 6

• Manufacturer Part Number: mga-87563
• Description: 0.5?4 Ghz 3 V Low Current Gaas Mmic Lna
• Manufacturer: Avago Technologies

Input Matching
The input of the MGA-87563 is partially matched
internally to 50 Ω. The use of a simple input conjugate
matching circuit (such as shown in Figure 10 for 2 GHz),
will lower the noise figure considerably. A significant
advantage of the MGA-87563’s design is that the
impedance match for NF
very close to a conjugate power match. This means that
a very low noise figure can be realized simultaneously
with a low input VSWR. The typical difference between
the noise figure obtainable with a conjugate power
match at the input and NF
Output Matching
The output of the MGA-87563 is matched internally to
50 Ω above 1.8 GHz. The use of a conjugate matching
circuit, such as a simple series inductor, can increase
the gain considerably at lower frequencies. Matching
the output will not affect the noise figure.
Stability
If the MGA-87563 is cascaded with highly reactive
stages (such as filters) some precautions may be needed
to ensure stability. The low frequency stability (under
1.5 GHz) of the MGA-87563 can be enhanced by adding
a series R-L network in shunt with the output, as shown
in Figure 12. The inductor can be either a chip
component or a high impedance transmission line as
shown in the figure. Component values are selected
such that the output of the MGA-87563 will be resistively
loaded at low frequencies while allowing high frequency
signals to pass the stability load with minimal loss.
Figure 12. Output Circuitry for Low Frequency Stability.
Typical values for the resistor are in the 25 to 50Ω
range. A suggested starting place for the inductor is a
0.35 to 0.40-inch long microstripline with a width of
0.020 inches, using 0.031-inch thick FR-4 (ε
circuit board as the substrate.
For applications near 1.5 GHz, gain (and output power)
may be traded off for increased stability.
MGA
87563
25-50 Ω
HIGH IMPEDANCE
TRANSMISSION
OR INDUCTOR
o
DC BLOCKING
o
CAPACITOR
(minimum noise figure) is
is only about 0.2 dB.
OUTPUT
RF
r
= 4.8)
Some precautions regarding the V
MGA-87563 are also recommended to ensure stability
within the operating frequency range of the device. It is
important that the connection to the power supply be
properly bypassed to realize full amplifier performance.
Refer to the Biasing section above for more information.
SOT-363 PCB Layout
A PCB pad layout for the miniature SOT-363 (SC-70)
package is shown in Figure 13 (dimensions are in
inches). This layout provides ample allowance for
package placement by automated assembly equipment
without adding parasitics that could impair the high
frequency RF performance of the MGA-87563. The
layout is shown with a nominal SOT-363 package
footprint superimposed on the PCB pads.
Figure 13. Recommended PCB Pad Layout for Avago’s SC70
6L/SOT-363 Products.
RF Layout
The RF layout in Figure 14 is suggested as a starting
point for designs using the MGA-87563 amplifier.
Adequate grounding is needed to obtain maximum
performance and to obviate potential instability. All
three ground pins of the MMIC should be connected to
RF ground by using plated through holes (vias) near
the package terminals.
Figure 14. RF Layout.
RF OUTPUT
0.039
50 Ω
0.026
Dimensions in inches.
6
87
0.018
dd
V
RF INPUT
DD
connection of the
50 Ω
0.079