DC – 50 GHz Variable Attenuator
Technical Data
HMMC-1002
Features
• Specified Frequency Range:
DC -26.5 GHz
• Return Loss:
10 dB
• Minimum Attenuation:
2.0 dB
• Maximum Attenuation:
30.0 dB
Description
The HMMC-1002 is a monolithic,
voltage variable, GaAs IC attenua-
tor that operates from DC to
50 GHz. It is fabricated using
MWTC’s MMICB process which
features an MBE epitaxial layer,
backside ground vias, and FET
gate lengths of approximately
0.4 mm. The variable resistive
elements of the HMMC-1002 are
two 750 mm wide series FETs
and four 200 mm wide shunt
FETs. The distributed topology of
the HMMC-1002 minimizes the
parasitic effects of its series and
shunt FETs, allowing the
HMMC-1002 to exhibit a wide
dynamic range across its full
bandwidth. An on-chip DC
reference circuit may be used to
maintain optimum VSWR for any
attenuation setting or to improve
the attenuation versus voltage
linearity of the attenuator circuit.
Chip Size:
Chip Size Tolerance:
Chip Thickness:
RF Pad Dimensions:
DC Pad Dimensions:
1470 x 610
µm
(57.9 x 24.0 mils)
±
10
µm
(± 0.4 mils)
127
±
15
µm
(5.0
±
0.6 mils)
60 x 70
µm
(2.4 x 2.8 mils), or larger
75 x 75
µm
(3.0 x 3.0 mils), or larger
Absolute Maximum Ratings
[1]
Symbol
V
DC-RF
V
1
V
2
V
DC
P
in
T
mina
T
maxa
T
STG
T
max
Parameters/Conditions
DC Voltage to RF Ports
V
1
Control Voltage
V
1
Control Voltage
DC In/DC Out
RF Input Power
Minimum Ambient
Operating Temperature
Maximum Ambient
Operating Temperature
Storage Temperature
Maximum Assembly Temp.
Units
V
V
V
V
dBm
°C
°C
°C
°C
-65
-55
+125
+165
+300
Min.
-0.6
-5.0
-5.0
-0.6
Max.
+1.6
+0.5
+0.5
+1.0
17
Note:
1. Operation in excess of any one of these conditions may result in permanent
damage to this device.
5965-5452E
7-12
Applications
The HMMC-1002 is designed to be
used as a gain control block
in an AGC assembly. Because of
its wide dynamic range and
return loss performance, the
HMMC-1002 may also be used as
a broadband pulse modulator or
single-pole single-throw, non-
reflective switch.
Operation
The attenuation of the
HMMC-1002 is adjusted by
applying negative voltages to V1
and V2. V1 controls the drain-to-
source resistances of the series
FETs while V2 controls the drain-
to-source resistances of the shunt
FETs. For any HMMC-1002 the
values of V1 may be adjusted so
that the device attenuation versus
voltage is monotonic for both V1
and V2; however, this will slightly
degrade the input and output
return loss.
The attenuation of the
HMMC-1002 may also be con-
trolled using only a single input
voltage by utilizing the on-chip
DC reference circuit and the
driver circuit shown in Figure 4.
This circuit optimizes VSWR for
any attenuation setting. Because
of process variations, the values
of V
REF
, R
REF
, and R
L
are different
for each wafer if optimum
performance is required. Typical
values for these elements are
given. The ratio of the resistors
R1 and R2 determines the sensi-
tivity of the attenuation versus
voltage performance of the
attenuator. For more information
on the performance of the
HMMC-1002 and the driver
circuits previously mentioned see
MWTC’s Application Note #37,
“HMMC-1002 Attenuator: Attenua-
tion Control.” For more
S-parameter information, see
MWTC’s Application Note #44,
“HMMC-1002 Attenuator:
S-Parameters.”
Assembly Techniques
Solder die attach using a AuSn
solder preform is the recom-
mended assembly method;
however, an epoxy die attach
method using ABLEBOND
®
71-1LM1 or ABLEBOND
®
36-2
may also be employed. Gold
thermosonic wedge bonding with
0.7 mil wire is the recommended
method for bonding to the device.
Tool force should be
22 grams
±
1 gram, stage tempera-
ture is 150
±
2
°C,
and ultrasonic
power and duration of 64
±
1 dB
and 76
±
8 msec, respectively.
The top and bottom metallization
is gold.
For more detailed information
see HP application note #999
“GaAs MMIC Assembly and
Handling Guidelines.”
GaAs MMICs are ESD sensitive.
Proper precautions should be used
when handling these devices.
RF
IN
RF
OUT
DC Reference Circuit
DC
IN
V
1
DC
OUT
V
2
Figure 1. HMMC-1002 Schematic.
7-14
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