5

MGA-86563 Applications Information

Introduction

The MGA-86563 is a high gain, low noise RF amplifier for

use in wireless RF applications within the 0.5 to 6  GHz

frequency range. The MGA-86563 is a three-stage, GaAs

Microwave Monolithic Integrated Circuit (MMIC) amplifier

that uses internal feedback to provide wideband gain and

impedance matching.

A patented, active bias circuit makes use of current sources

to“re-use”the drain current in all three 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

test

and G

test

parameters

shown in the Electrical Specifications Table.

The 3.3 nH inductor, L1 (Coilcraft, Cary, IL or equivalent)

in series with the input of the amplifier matches the input

to 50Ω at 2 GHz.

The parameter test circuit uses a high impedance RF choke

to apply V

d

to the MMIC while isolating the power supply

from the RF Output of the amplifier.

Biasing

The MGA-86563 is a voltage-biased device and operates

from a single +5 volt power supply. With a typical current

drain of only 14 mA, the MGA-86563 is suitable for use

in battery powered applications. RF performance is very

stable over a wide variation of power supply voltage.

Since DC bias is applied to the MGA-86563 through the RF

Output pin, some method of isolating the RF from the DC

must be provided. An RF choke or length of high imped-

ance transmission line is typically used for this purpose.

SOT-363 PCB Layout

A PCB pad layout for the miniature SOT-363 (SC-70)

package used by the MGA-86563 is shown in Figure 12

(dimensions are in inches). This layout provides ample al-

lowance for package placement by automated assembly

equipment without adding parasitics that could impair

the high frequency RF performance of the MGA-86563.

The layout is shown with a nominal SOT-363 package

footprint superimposed on the PCB pads.

Figure 12. Recommended PCB Pad Layout for Avago’s SC70 6L/SOT-363

Products.









'LPHQVLRQVLQ,QFKHV

Vd

C1

L1

3.3 nH

w = 110

(50

Ω)

RF

INPUT

RF

OUTPUT

w = 110

(50

Ω)

w = 110

I = 110

RFC

(28 nH)

BOARD MATERIAL = 1/16" FR-4

w = 15

I = 1000

REFERENCE

PLANES

TEST CIRCUIT

Figure 10. Test Circuit for 2 GHz.

Phase Reference Planes

The positions of the reference planes used to measure S-

Parameters and to specify

*

opt

for the Noise Parameters are

shown in Figure 11. As seen in the illustration, the reference

planes are located at the extremities of the package leads.

Figure 11. Reference Planes.