HMC473MS8_08 Datasheet, PDF(7/8 Page) Hittite Microwave Corporation – GaAs MMIC VOLTAGE VARIABLE ATTENUATOR, 0.45

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HMC473MS8_08 Datasheet, PDF (7/8 Pages) Hittite Microwave Corporation – GaAs MMIC VOLTAGE VARIABLE ATTENUATOR, 0.45 - 2.2 GHz

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HMC473MS8 / 473MS8E

v01.1105

GaAs MMIC VOLTAGE VARIABLE

ATTENUATOR, 0.45 - 2.2 GHz

Attenuation Linearizing Control Circuit

For The HMC473MS8 / HMC473MS8E Voltage Variable Attenuator

A driver circuit to improve the attenuation linearity of the HMC473MS8 & HMC473MS8E can be implemented with a

simple op-amp configuration. A breakpoint linearization circuit will scale the voltage supplied to the control line of the

HMC473MS8 & HMC473MS8E, so that a more linear attenuation vs. control voltage slope can be achieved. A -3.3V

and +3.3V supply is required.

Diode and resistor values which define the op-amp gain, and breakpoint were selected to optimize a measured

production lot of attenuators at 0.9 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 0.9 GHz attenuation applications. A similar approach may be used at

other frequencies by adjusting R1 - R9 resistor values.

Application Circuit

Required Parts List

Part

AD822

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

Digi-Key

5 - 162

For price, delivery, and to place orders, please contact Hittite Microwave Corporation:

20 Alpha Road, Chelmsford, MA 01824 Phone: 978-250-3343 Fax: 978-250-3373

Order On-line at www.hittite.com

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