MICROWAVE CORPORATION
HMC121
General Description
The HMC121 chip is an absorptive voltage
variable attenuator. It features an on-chip
reference attenuator for use with an external
op-amp to provide simple single voltage
attenuation control. The device is ideal in
designs where analog control signal must
control RF signal levels over a 30 dB range,
such as AGC circuits and in temperature
compensation of multiple gain stages. Ap-
plications include military ECM and com-
munications as well as commercial micro-
wave radios and VSAT. See SMT pack-
aged version HMC121G8 (hermetic).
GaAs MMIC VOLTAGE-VARIABLE ATTENUATOR DC - 15 GHz
SEPTEMBER 1999
Features
WIDE BANDWIDTH: DC - 15 GHZ
LOW PHASE SHIFT VS. ATTENUATION
2
Attenuators
30 dB ATTENUATION RANGE
SIMPLIFIED VOLTAGE CONTROL
Guaranteed Performance,
50 ohm system, -55 to +85 deg C
Parameter
Insertion Loss
Attenuation Range
Return Loss
Switching Characteristics
DC - 8 GHz:
DC - 15 GHz:
tRISE, tFALL ( 10/90% RF):
tON, tOFF (50% CTL to 10/90% RF):
Min. Atten:
Atten. > 2dB:
Min. Atten:
Atten. > 2dB:
DC - 8 GHz:
DC - 15 GHz:
25
13
10
Min.
Typ.
1.8
2
30
18
15
3
6
+10
-2
+25
+10
Max.
2.8
3.5
Units
dB
dB
dB
dB
dB
ns
ns
dBm
dBm
dBm
dBm
Input Power for 0.25dB Comp. ( 0.5 - 15 GHz)
Input Third Order Intercept
(two - 8 dBm signals 0.5 - 15 GHz)
12 Elizabeth Drive, Chelmsford, MA 01824
Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
2-6
MICROWAVE CORPORATION
HMC121 VOLTAGE-VARIABLE ATTENUATOR DC - 15 GHz
SEPTEMBER 1999
Insertion Loss
0
-1
Relative Attenuation
0
INSERTION LOSS (dB)
-2
ATTENUATION (dB)
-10
-20
-3
-4
-5
0
2
4
6
8
10
12
14
16
2
Attenuators
-30
-40
0
2
4
6
8
10
FREQUENCY (GHz)
12
14
16
FREQUENCY (GHz)
Return Loss
0
Relative Attenuation vs.
Control Voltage
0
-0.5
-1
-1.5
-2
-2.5
-3
V1
V2
CONTROL VOLTAGE
RETURN LOSS (dB)
-10
-20
-30
0
2
4
6
8
10
12
14
16
0
5
FREQUENCY (GHz)
10
15
20
25
RELATIVE ATTENUATION (dB)
30
Relative Phase
90
RELATIVE PHASE (DEG)
70
50
30
20 dB
10 dB
10
-10
0
2
4
6
8
10
12
14
16
FREQUENCY (GHz)
1 dB and 3 dB
12 Elizabeth Drive, Chelmsford, MA 01824
Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
2-7
MICROWAVE CORPORATION
HMC121 VOLTAGE-VARIABLE ATTENUATOR DC - 15 GHz
SEPTEMBER 1999
Schematic
50
50
Single-Line Control Driver
RF2
50
50
RF1
RF1
RF2
2
500
500
500
500
500
500
500
Attenuators
V2
500
I
O V1
CTL
+5V
1N4148
500
V2 I
(BACKSIDE IS GND)
O V1
3.9K
500
3.9K
TL321
OR EQUIVALENT
-5V
External op-amp control circuit maintains impedance match while
attenuation is varied. Input control ranges from 0 Volts (min.
attenuation) to -2.5 Volts (max. attenuation.)
Outline Drawing
Absolute Maximum Ratings
RF Input
Control Voltage Range
0.87 (0.034)
+16dBm
+1.0 to -6.0 Vdc
-65 to +150 deg C
-55 to +125 deg C
Storage Temperature
Operating Temperature
PORT RF2
0.12 (0.005)
PORT RF1
1.10
(0.043)
0.67
(0.026)
V2
Hittite
V1
PORT V1
ALL TOLERANCES ARE: ± 0.025 (0.001)
DIE THICKNESS IS 0.10 (0.004), BACKSIDE IS GROUND
BOND PADS ARE 0.10 (0.004) SQUARE
ALL DIMENSIONS IN MILLIMETERS (INCHES)
BACKSIDE METALLIZATION: GOLD
BOND PAD METALLIZATION: GOLD
0.09 (0.003)
0.21 (0.008)
0.24 (0.009)
0.39 (0.015)
0.54 (0.021)
PORT O
PORT I
PORT V2
12 Elizabeth Drive, Chelmsford, MA 01824
Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
2-8
MICROWAVE CORPORATION
HMC121 VOLTAGE-VARIABLE ATTENUATOR DC - 15 GHz
SEPTEMBER 1999
Handling Precautions
Follow these precautions to avoid permanent damage.
Cleanliness: Handle the chips in a clean environment. DO NOT attempt to clean the chip using liquid
cleaning systems.
Static Sensitivity: Follow ESD precautions to protect against > ± 250V ESD strikes. (
see page 8 - 2
)
Transients: Suppress instrument and bias supply transients while bias is applied. Use shielded signal and
bias cables to minimize inductive pick-up.
General Handling: Handle the chip along the edges with a vacuum collet or with a sharp pair of bent twee-
zers. The surface of the chip has fragile air bridges and should not be touched with vacuum collet, twee-
zers, or fingers.
2
Attenuators
Mounting
The chip is back-metallized and can be die mounted with AuSn eutectic preforms or with electrically
conductive epoxy. The mounting surface should be clean and flat.
Eutectic Die Attach:
A 80/20 gold tin preform is recommended with a work surface temperature of 255 deg. C and a tool tem-
perature of 265 deg. C. When hot 90/10 nitrogen/hydrogen gas is applied, tool tip temperature should be
290 deg. C.
DO NOT expose the chip to a temperature greater than 320 deg. C for more than 20 seconds. No more
than 3 seconds of scrubbing should be required for attachment.
Epoxy Die Attach:
Apply a minimum amount of epoxy to the mounting surface so that a thin epoxy fillet is observed around
the perimeter of the chip once it is placed into position.
Cure epoxy per the manufacturer's schedule.
Wire Bonding
Ball or wedge bond with 1.0 diameter pure gold wire. Thermosonic wirebonding with a nominal stage
temperature of 150 deg. C and a ball bonding force of 40 to 50 grams or wedge bonding force of 18 to 22
grams is recommended. Use the minimum level of ultrasonic energy to achieve reliable wirebonds.
Wirebonds should be started on the chip and terminated on the package. RF bonds should be as short as
possible.
12 Elizabeth Drive, Chelmsford, MA 01824
Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
2-9
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