mga-87563 Avago Technologies, mga-87563 Datasheet - Page 5

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

MGA-87563 Applications Information
Introduction
The MGA-87563 low noise RF amplifier is designed to
simplify wireless RF applications in the 0.5 to 4 GHz
frequency range. The MGA-87563 is a two-stage, GaAs
Microwave Monolithic Integrated Circuit (MMIC) ampli-
fier that uses feedback to provide wideband gain. The
output is matched to 50Ω and the input is partially
matched for optimum noise figure.
A patented, active bias circuit makes use of current
sources to “re-use” the drain current in both stages of
gain, thus minimizing the required supply current and
decreasing sensitivity to variations in power supply
voltage.
Test Circuit
The circuit shown in Figure 10 is used for 100% RF
testing of Noise Figure and Gain. The input of this
circuit is fixed tuned for a conjugate power match
(maximum power transfer, or, minimum Input VSWR)
at 2 GHz. Tests in this circuit are used to guarantee the
NF
Specifications table.
The 4.7 nH inductor, L1 (Coilcraft, Cary, IL part number
series 1008CT-040) placed in series with the input of
the amplifier is all that is necessary to match the input
to 50Ω at 2 GHz.
Figure 10. Test Circuit for 2 GHz.
Phase Reference Planes
The positions of the reference planes used to measure
S-Parameters and to specify Γ
Parameters are shown in Figure 11. As seen in the
illustration, the reference planes are located at the
extremities of the package leads.
test
and G
INPUT
RF
test
50 Ω
parameters shown in the Electrical
4.7 nH
L1
C1
V
10 Ω
dd
50 Ω
opt
OUTPUT
for the Noise
RF
Figure 11. Reference Planes.
Biasing
The MGA-87563 is a voltage-biased device and operates
from a single +3 volt power supply. With a typical
current drain of only 4.5 mA, the MGA-87563 is very
well suited for use in battery powered applications. All
bias regulation circuitry is integrated into the MMIC,
eliminating the need for external DC components. RF
performance is very consistent for 3-volt battery
supplies that may range from 2.7 to 3.3 volts, depending
on battery “freshness” or state of charge for
rechargeable batteries. Operation up to +5 volts is
discussed at the end of the Applications section.
The test circuit in Figure 10 illustrates a suitable
method for bringing bias into the MGA-87563. The bias
connection must be designed so that it adequately
bypasses the V
creating any resonances at frequencies where the MGA-
87563 has gain.
The 10Ω resistor, R1, serves to “de-Q” any potential
resonances in the bias line that could lead to low gain,
unwanted gain variations or device instability. The
power supply end of R1 is bypassed to ground with
capacitor C1. The suggested value for C1 is 100 pF.
Significantly higher values for C1 are not recommended.
Many higher value chip capacitors (e.g., 1000 pF) are
not of sufficiently high quality at these frequencies to
function well as a RF bypass without adding harmful
parasitics or self-resonances.
While the input and output terminals are internally
resistively grounded, these pins should not be
considered to be current sinks. Connection of the
MGA-87563 amplifier to circuits that are at ground
potential may be made without the additional cost and
PCB space needed for DC blocking capacitors. If the
amplifier is to be cascaded with active circuits having
non-zero voltages present, the use of series blocking
capacitors is recommended.
dd
terminal while not inadvertently
TEST CIRCUIT
REFERENCE
PLANES
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