2 - 14
12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
MICROWAVE CORPORATION
F
EBRUARY
2001
A
TTENU
A
T
ORS
2
SMT
General Description
WIDE BANDWIDTH: DC - 10 GHz
LOW PHASE SHIFT VS. ATTENUATION
25 dB ATTENUATION RANGE
SIMPLIFIED VOLTAGE CONTROL
The HMC121C8 is an absorptive Voltage
Variable Attenuator (VVA) in a non-hermetic
surface-mount package covering DC - 10
GHz. It features an on-chip reference at-
tenuator for use with an external op-amp to
provide simple single voltage attenuation
control, 0 to -3V. The device is ideal in
designs where an analog DC control signal
must control RF signal levels over a 25 dB
amplitude range. Applications include AGC
circuits and temperature compensation of
multiple gain stages in microwave point-to-
point and VSAT radios. See HMC121G8
for a hermetic SMT version of this device.
Features
Guaranteed Performance,
50 ohm system, -55 to +85 deg C
GaAs MMIC SMT VOLTAGE-VARIABLE ATTENUATOR DC - 10 GHz
HMC121C8
Parameter
Min
Typical
Max
Units
Inse rtion L oss
DC - 6
GHz :
DC - 8
GHz :
DC - 10 GHz :
2.0
2.2
3.5
2.5
3.2
4.5
dB
dB
dB
Attenuation Range
DC - 6
GHz:
DC - 10 GHz :
20
25
25
30
dB
Return Loss
DC - 8
GHz:
DC - 10 GHz :
11
8
15
12
dB
dB
Switching Characteristics
tRISE, tFALL (10/90% RF):
tON, tOFF (50% CTL to 10/90% RF):
3
6
ns
ns
Input Power for 0.25 dB C ompre ssion
(0.5 - 10 GHz)
Min. Atten:
Atten. >2 dB:
+3
-3
dBm
dBm
Input Third Order Intercept (two - 8 dBm
signals, 0.5 - 10 GHz)
Min. Atten:
+18
+10
dBm
dBm
V
03.0400
2 - 15
12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
MICROWAVE CORPORATION
F
EBRUARY
2001
2
A
TTENU
A
T
ORS
SMT
-40
-30
-20
-10
0
0
2
4
6
8
10
12
ATTENUATI
ON
(
d
B)
FREQUENCY (GHz)
18 dB
0 dB
3 dB
6 dB
12 dB
24 dB
-5
-4
-3
-2
-1
0
0
2
4
6
8
10
12
I
N
SERTI
ON
LOSS
(
d
B)
FREQUENCY (GHz)
+85 C
-40 C
+25 C
-35
-30
-25
-20
-15
-10
-5
0
0
2
4
6
8
10
12
RETURN
L
O
SS
(
d
B)
FREQUENCY (GHz)
S22
S11
-3
-2.5
-2
-1.5
-1
-0.5
0
0
5
10
15
20
25
30
CONTROL
V
OL
TAGE
(
V
d
c
)
RELATIVE ATTENUATION (dB)
V2
V1
-5
5
15
25
35
45
55
65
75
85
0
2
4
6
8
10
12
RELATI
VE
PHASE
(
D
EG)
FREQUENCY (GHz)
9 dB
3 dB
15 dB
21 dB
24 dB
Insertion Loss
Relative Attenuation
Return Loss
Relative Attenuation vs.
Control Voltage @ 4.2 GHz
Relative Phase
HMC121C8 SMT VOLTAGE-VARIABLE ATTENUATOR DC - 10 GHz
HMC121C8
-3
-2.5
-2
-1.5
-1
-0.5
0
0
5
10
15
20
25
30
CONTROL
V
OL
TAGE
(
V
d
c
)
RELATIVE ATTENUATION (dB)
V2
V1
Relative Attenuation vs.
Control Voltage @ 10 GHz
V
03.0400
2 - 16
12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
MICROWAVE CORPORATION
F
EBRUARY
2001
A
TTENU
A
T
ORS
2
SMT
10
20
30
40
50
60
0
1
2
3
4
5
6
7
8
9
10
SECO
N
D
O
RDER
I
NT
ERCEPT
(d
Bm)
FREQUENCY (GHz)
3 dB
Reference
10 dB
6 dB
5
10
15
20
25
30
0
1
2
3
4
5
6
7
8
9
10
T
H
I
R
D
O
RDER
I
NT
ERCEPT
(
d
Bm
)
FREQUENCY (GHz)
3 dB
Reference
10 dB
6 dB
-10
-5
0
5
10
15
0
1
2
3
4
5
6
7
8
9
10
1
d
B
C
O
M
PRESSI
O
N
(d
Bm)
FREQUENCY (GHz)
Reference
6 dB
-10
-5
0
5
10
15
0
1
2
3
4
5
6
7
8
9
10
0.
25
dB
CO
M
P
RE
S
S
I
O
N
(
d
B
m
)
FREQUENCY (GHz)
Reference
6 dB
HMC121C8 SMT VOLTAGE-VARIABLE ATTENUATOR DC - 10 GHz
Input Third Order
Intercept vs. Attenuation
Input Second Order
Intercept vs. Attenuation
Second Harmonic vs. Attenuation
0.25 dB Compression
vs. Attenuation
1 dB Compression
vs. Attenuation
30
40
50
60
70
0
1
2
3
4
5
6
7
8
9
10
SECO
N
D
H
ARMO
NI
C
(
d
B
c)
FREQUENCY (GHz)
3 dB
Reference
10 dB
6 dB
HMC121C8
V
03.0400
2 - 17
12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
MICROWAVE CORPORATION
F
EBRUARY
2001
2
A
TTENU
A
T
ORS
SMT
HMC121C8 SMT VOLTAGE-VARIABLE ATTENUATOR DC - 10 GHz
V1
O
I
V2
RF2
RF1
50
50
500
500
500
500
Schematic
Absolute Maximum Ratings
RF Input
+16dBm
Control Voltage Range
+1.0 to -6.0 Vdc
Storage Temperature
-65 to +150 deg C
Operating Temperature
-55 to +85 deg C
Outline Drawing
HMC121C8
1.
MATERIAL:
A) PACKAGE BODY & COVER : WHITE ALUMINA (92%)
B) LEADS & PACKAGE BOTTOM: COPPER
2 .
PLATING : ELECTROLYTIC GOLD 100 - 200 MICROINCHES
OVER ELECTROLYTIC NICKEL 100 TO 200 MICROINCHES.
3.
DIMENSIONS ARE IN INCHES (MILLIMETERS).
UNLESS OTHERWISE SPECIFIED TOL. ARE 0.005(0.13).
4.
ALL UNLABELED LEADS ARE GROUND. THESE LEADS ARE
CONNECTED INTERNALLY TO THE PACKAGED BOTTOM GROUND.
THE PACKAGE BOTTOM RF GROUND MUST BE SOLDERED TO
THE PCB RF GROUND.
5.
PACKAGE LENGTH AND WIDTH DIMENSIONS SHOWN DO NOT INCLUDE
LID SEAL PROTRUSION. ALLOWABLE PROTRUSION SHALL BE 0.005
(0.127MM) PER SIDE.
V
03.0400
2 - 18
12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343
Fax: 978-250-3373
Web Site: www.hittite.com
MICROWAVE CORPORATION
F
EBRUARY
2001
A
TTENU
A
T
ORS
2
SMT
Single-Line Control Driver
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.)
V1
O
I
V2
RF2
RF1
50
50
500
500
500
500
3.9K
3.9K
500
+5V
-5V
500
CTL
1N4148
TL321
OR EQUIVALENT
HMC121C8 SMT VOLTAGE-VARIABLE ATTENUATOR DC - 10 GHz
HMC121C8
V
02.0400
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