The RF input matching circuity
gives a 50Ω DC and RF path to
ground. A DC blocking capacitor
should be used in the RF input
transmission line. Any DC volt-
age applied to the RF input must
be maintained below 1V; DC
voltage on the RF output can
range from –7V to +13V.
tach requires 69°C ambient. It is
recommended that the RF input
and output connectors be made
using 500 lines per inch, or
equivalent gold wire mesh. The
RF connections should be kept
as short as possible to minimize
inductance. The DC bias supply
wires can be 0.7 mil diameter
gold.
Applications
The TC956 amplifier offers high
gain and power to mm frequen-
cies. It can be used in mm–wave
products with high power re-
quirements, or in conjunction
with a TC958 or TC906 in a
banded design.
Biasing and Operation
No ground wires are needed
since ground connections are
made with plated through–holes
to the backside of the device.
MMIC ESD precautions, han-
dling considerations, and die at-
tach and bonding methods are
critical factors in successful
GaAs MMIC performance and
reliability.
The recommended bias condi-
tions are to connect the drains
to a shared 3V supply and con-
nect all gate pads to a shared,
adjustable negative voltage. The
gate voltage is adjusted for total
drain supply current of 330 mA.
Drain pains 2–4 are internally
connected; either multiple
bonds or a single bond is accept-
able. Positive gate voltage can
generate drain currents as high
as 700 mA, so be sure that the
bonds have sufficient capacity.
Likewise, all gates can be con-
trolled with a single bond wire
Reliability limits assume long–
term operation into a 50Ω
match, with short–term excur-
sions to an open circuit. Reli-
ability will be degraded with
long–term operation into an
open circuit.
Additional Information
Agilent application note #54,
"GaAs MMIC ESD, Die Attach
and Bonding Guidelines" pro-
vides additional information on
these subjects.
Assembly Techniques
For most applications, we rec-
ommend solder die attach. Reli-
ability goals are modeled using
solder attach to an infinite heat
sink at 85°C ambient. Epoxy at-
attached to V
.
G4
VD1
VD2
VD4
VD3
GND
Total FET Width=1040 um
Total Gm=513 mSie
RFIN
.
RFOUT
600 Ohm
600 Ohm
600 Ohm
600 Ohm
VG1
VG2
VG4
VG3
GND
Figure 1.
1GG6-4070 Schematic
Figure 1.
1GG6-8070 Schematic
TC956/rev.3.2
3