7
Biasing and Operation
The AMMC-6220 is normally biased with a single positive
drain supply connected to both VD1 and VD2 bond pads
through the 2 bypass capacitors as shown in Figure 20.
The recommended supply voltage is 3 V. It is important
to have 2 separate 100pF bypass capacitors, and these
two capacitors should be placed as close to the die as
possible.
The AMMC-6220 does not require a negative gate volt-
age to bias any of the three stages. No ground wires are
needed because all ground connections are made with
plated through-holes to the backside of the device.
Refer the Absolute Maximum Ratings table for allowed
DC and thermal conditions
Assembly Techniques
The backside of the MMIC chip is RF ground. For mi-
crostrip applications the chip should be attached directly
to the ground plane (e.g. circuit carrier or heatsink) using
electrically conductive epoxy[1,2]
For best performance, the topside of the MMIC should
be brought up to the same height as the circuit sur-
rounding it. This can be accomplished by mounting a
gold plate metal shim (same length and width as the
MMIC) under the chip which is of correct thickness to
make the chip and adjacent circuit the same height.
The amount of epoxy used for the chip and/or shim
attachment should be just enough to provide a thin
llet around the bottom perimeter of the chip or shim.
The ground plan should be free of any residue that may
jeopardize electrical or mechanical attachment.
Figure 19. AMMC-6220 Schematic
The location of the RF bond pads is shown in Figure
12. Note that all the RF input and output ports are in a
Ground-Signal-Ground conguration.
RF connections should be kept as short as reasonable
to minimize performance degradation due to undesir-
able series inductance. A single bond wire is normally
sucient for signal connections, however double bond-
ing with 0.7 mil gold wire or use of gold mesh is recom-
mended for best performance, especially near the high
end of the frequency band.
Thermosonic wedge bonding is preferred method for
wire attachment to the bond pads. Gold mesh can be
attached using a 2 mil round tracking tool and a tool
force of approximately 22 grams and a ultrasonic power
of roughly 55 dB for a duration of 76 ± 8 mS. The guided
wedge at an untrasonic power level of 64 dB can be
used for 0.7 mil wire. The recommended wire bond
stage temperature is 150 ± 2 °C.
Caution should be taken to not exceed the Absolute
Maximum Rating for assembly temperature and time.
The chip is 100um thick and should be handled with
care. This MMIC has exposed air bridges on the top
surface and should be handled by the edges or with a
custom collet (do not pick up the die with a vacuum on
die center).
This MMIC is also static sensitive and ESD precautions
should be taken.
Notes:
1. Ablebond 84-1 LM1 silver epoxy is recommended.
2. Eutectic attach is not recommended and may jeopardize reliability
of the device.