September 2010 - Rev 07-Sep-10

Page 6 of 8

7.5-22.5/15.0-45.0 GHz Active Doubler

QFN, 3x3 mm

App Note [1] Biasing

Vg1=-0.6V. The typical DC currents are Id1=80mA, Id2=140mA and Iss=50mA. Vg2 can be used for active control biasing of Vd2, or it

can be set to GND and Vd2 will self bias at approximately 140mA. Maximum output power is achieved with Vss=-5.0V and Iss=50mA

but the device will operate with reduced bias to Vss=-2.0V and Iss=25mA. It is also recommended to use active biasing on Vd2 with

Vg2 to keep the currents constant as the RF power and temperature vary; this gives the most reproducible results. Depending on the

supply voltage available and the power dissipation constraints, the bias circuit may be a single transistor or a low power operational

amplifier, with a low value resistor in series with the drain supply used to sense the current.The gate of the pHEMT is controlled to

maintain correct drain current and thus drain voltage.The typical gate voltage for Vg2=-0.1V.Typically the gate is protected with

Silicon diodes to limit the applied voltage. Also, make sure to sequence the applied voltage to ensure negative gate bias is available

before applying the positive drain supply.

MTTF

Bias Conditions: Vd1=Vd2=4.0V, Id1=40 mA, Id2=140 mA,Vss=-5.0V, Iss=50mA

X1000-QT

1.0E+00

1.0E+01

1.0E+02

1.0E+03

1.0E+04

1.0E+05

55

65

75

85

95

Temperature (°C)

MTTF is calculated from accelerated life-time data of single devices and assumes isothermal back-plate.

Bias Conditions: Vd1,2 = 5.0V, Id1,2 = 220 mA, Vss = -5.0V, Iss = 50 mA

Mimix Broadband, Inc., 10795 Rockley Rd., Houston,Texas 77099

Tel: 281.988.4600 Fax: 281.988.4615 mimixbroadband.com

Characteristic Data and Specifications are subject to change without notice. ©2010 Mimix Broadband, Inc.

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