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M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make

changes to the product(s) or information contained herein without notice.

8

Active Doubler

7.5-22.5/15.0-45.0 GHz

XX1000-QT

ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions

is considering for development. Performance is based on target specifications, simulated results,

and/or prototype measurements. Commitment to develop is not guaranteed.

PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology

Solutions has under development. Performance is based on engineering tests. Specifications are

typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.

Commitment to produce in volume is not guaranteed.

Rev. V1

App Note [1] Biasing - It is recommended to separately bias each doubler stage with fixed voltages of Vd(1,2)

=5.0V, Vss=-5.0V and 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 sup-

ply 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.