HMC173MS8(V01) 데이터 시트보기 (PDF) - Hittite Microwave
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HMC173MS8 Datasheet PDF : 6 Pages
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v01.0801
HMC173MS8
GaAs MMIC VOLTAGE-VARIABLE
ATTENUATOR, 0.8 - 2.0 GHz
Attenuation Linearizing Control Circuit
For The HMC173MS8 Voltage Variable Attenuator
A driver circuit to improve the attenuation linearity of the HMC173MS8 can be implemented with a simple op-amp con-
9
figuration. A breakpoint linearization circuit will scale the voltage supplied to the control line of the HMC173MS8, so that
a more linear attenuation vs. control voltage slope can be achieved. A -5V and +5V supply is required.
Diode and resistor values which define the op-amp gain, and breakpoint were selected to optimize a measured produc-
tion lot of attenuators at .825 GHz. R7 may be varied to optimize the performance of any given attenuator. If the input
voltage to the linearizing circuit will not drop below 1.0V, the R9 and D2 may be omitted, and this will greatly reduce the
overall power consumption of the driver circuit.
The linearizing circuit has been optimized for .825 GHz attenuation applicaitons. A similar approach may be used at
other frequencies by adjusting R1 - R9 resistor values.
Required Parts List
Application Circuit
Part
AD822
R1
R2
R3
R4
R5
R6
R7
R8
R9
D1, D2
Description
Op-Amp
10K ohms
200K ohms
7.5K ohms
39K ohms
220K ohms
91K ohms
910 ohms
51 ohms
100 ohms
LL4148 D-35
Manufacturer
Analog Devices
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Digi-Key
Return Loss vs.
Control Voltage @ .825 GHz
-12
-13
-14
Without
Linearizer
-15
-16
With
Linearizer
-17
-18
-19
0.5
1
1.5
2
2.5
3
CONTROL VOLTAGE (Vdc)
Attenuation vs.
Control Voltage @ .825 GHz
0
-10
Without
Linearizer
-20
With
Linearizer
-30
-40
-50
-60
0
1
2
3
CONTROL VOLTAGE (Vdc)
9-6
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12 Elizabeth Drive, Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373
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