Biasing and Operation
The AMMC-6231 is normally
biased with a positive supply
connected to both V
D1
and V
D2
bond pads through the 100pF
bypass capacitor as shown in
Figure 21. The recommended
supply voltage is 3 V. It is
important to place the bypass
capacitor as close to the die as
possible. No negative gate bias
voltage is needed for the
AMMC-6231. Input and
output matching are achieved
on-die, therefore no other
external component is required
besides one 100pF bypass
capacitor for the main supply.
The input and output are DC-
blocked with internal coupling
capacitors.
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 microstrip
applications the chip should be
attached directly to the ground
plane (e.g. circuit carrier or
heatsink) using electrically
conductive epoxy
[1]
For best performance, the
topside of the MMIC should be
brought up to the same height
as the circuit surrounding 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 fillet 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.
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 configuration.
RF connections should be kept
as short as reasonable to
minimize performance
degradation due to undesirable
series inductance. A single
bond wire is normally
sufficient for signal
connections, however double
bonding with 0.7 mil gold wire
or use of gold mesh
[2]
is
recommended for best
performance, especially near
the high end of the frequency
band.
VD1
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
+/- 2C.
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] Buckbee-Mears Corporation, St. Paul, MN,
800-262-3824
VD2
RFout
RFin
Figure 17. AMMC-6231 Simplified Schematic
7
HP [ AGILENT(HEWLETT-PACKARD) ]
