4
Applications Information
Operation of the AMMC- 3041 is
very straightforward. The RF,
LO, and IF ports can be
connected directly to 50- ohm
circuits. None of the three ports
should have a DC voltage
applied to them. If DC voltages
are present, a blocking capacitor
should be used.
Some enhancement in
Conversion Loss may be
obtained by reflectively
terminating the LO and RF
signals at the IF port. This is
easily done by connecting a 20-
mil long bond wire from the IF
output pad on the MMIC to a
shunt, off- chip 0.5 pF chip
capacitor as indicated in Figure
7.
For up conversion applications,
the input signal is normally
applied to the IF port, the local
oscillator connected to the LO
port, and the up-converted
output signal taken from the RF
port.
Assembly Techniques
The backside of the AMMC- 3041
chip is RF ground. For
microstripline applications, the
chip should be attached directly
to the ground plane (e.g., circuit
carrier) 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 plated metal
shim (same length and width as
the MMIC) under the chip,
which is of the correct
thickness to make the chip and
adjacent circuit coplanar.
The amount of epoxy used for
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 plane should
be free of any residue that may
jeopardize electrical or
mechanical attachment.
For use on coplanar circuits,
the chip can be mounted
directly on the topside ground
plane of the circuit.
The location of the RF, LO, and
IF bond pads is shown in
Figure 8. Note that all I/O ports
are in a Ground- Signal- Ground
configuration. The IF port is
located near the middle of the
die, which allows this
connection to be made from
either side of the chip for
maximum layout flexibility.
RF connections should be kept
as short as reasonable to
minimize performance
degradation due to series
inductance. A single bond wire
is sufficient for all signal
connections. However, double-
bonding with 0.7 mil gold wire
or the use of gold mesh[2] is
recommended for best
performance, especially near the
high end of the frequency range.
Thermosonic wedge bonding is
the 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 with an
ultrasonic power of roughly 55
dB for a duration of 76 ± 8 mS.
A guided wedge at an ultrasonic
power level of 64 dB can be
used for the 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 100 µm 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 die with vacuum on die
center.)
This MMIC is also static
sensitive and ESD handling
precautions should be taken.
Notes:
1. Ablebond 84-1 LM1 silver epoxy is
recommended.
2. Buckbee-Mears Corporation, St. Paul, MN,
800-262-3824