MMIC AN710

INTRODUCTION
This application note describes the use and handling of AMCOM's BM FET MMIC
power amplifiers. The amplifiers are housed in a 10-pin low cost surface mountable,
ceramic package. The MMIC can be handled by standard pick and place equipment.
ELECTRICAL SCHEMATIC
Figure 1 shows the detailed schematic and pin assignment of AMCOM's BM MMIC
power amplifiers. External DC decoupling and filtering components are added to
ensure stability of the amplifier and to prevent any possible spurious signal due to
noisy supplies. A good ground is required for maintaining stability. The following table describes the pin
assignment of the amplifier:
BM PIN ASSIGNMENT
Pin Signal Description
1, 2, 10 Vds
Positive Drain
Voltage
3 RF in RF power input
4, 9 Ground RF and DC Ground
5, 6, 7 Vgs
Negative gate
Voltage
8 RF out RF power output
BIAS CONSIDERATIONS
Drain bias
The amplifier is designed to operate within specifications when biased with drain voltage/current as specified in the
datasheet. If the MMIC is mounted on a ridged heat sink (see Figure 4A), it can be biased at a higher Vds (about
1-2 V higher). In all cases the absolute maximum rating for voltage, current, or power dissipation must not be
exceeded. The DC drain current can be controlled by the negative gate voltage. If the MMIC is biased with a
current and/or voltage less than Idq then the gain and P1dB will be reduced.
Gate bias
As with all GaAs amplifiers, it is important to ensure that the gate bias is present before applying the drain voltage.
Without gate control, the drain current will rise to a level that is potentially destructive to the MMIC; therefore, it is
Application Note
AN710
AM324036WM-BM-R
March 2006 Rev 5
Figure 1
recommended to provide safeguards in the circuit design to ensure that the gate bias is applied first. The gate
voltage should be adjusted such that the drain current is equal to Idq.
HANDLING
The amplifier is based on GaAs FET (MESFET or PHEMT) technology; therefore, it is sensitive to electrostatic
discharge (ESD). AMCOM ships all power amplifier MMICs in electrostatic protection packages. Users must be
careful when handling the amplifier and should follow the standard ESD prevention techniques. A grounded wrist
strap will give adequate protection against electrostatic charge, and workbenches should have antistatic mats.
PACKAGE TYPE "BM" MOUNTING
AMCOM's "BM" type package (Figure 2) is a low cost, leaded surface mountable, ceramic package with a ceramic
lid. The package is designed to be mounted in a standard automated SMT reflow soldering process. The package
has a metal base pad at the bottom of the package, which serves as DC and RF ground, and as a thermal path to
remove the heat generated by the MMIC. The ground base should be soldered to the heat sink. The RF input and
output leads should be soldered to the microwave circuit on the PC board.
All dimensions in inch