Motorola Corporation

Signal One Corporation

Helge O Granberg

Don P Roehrs

Lawrence F Cygan

Carl Missele

Samuel L Coffman

Richard S Bickham

A broadband RF transformer design is described that facilitates the construction of a broadband impedance transformer in a compact, planar format, while retaining ease of assembly and manufacture. Broadband operation is achieved through the use of a slotted low-impedance winding structure, common-manufacture ferrite elements, and the optional placement of reactive elements between winding turns. By virtue of construction, thermal performance is enhanced, allowing operation at power levels not previously possible. The invention accommodates functional tuning via laser or abrading techniques. Also, the winding configuration eliminates the need to access the center of a spiral for the purposes of establishing a ground connection.

Broadband RF transformer

Switching power amplifier circuits for use in a frequency range from 0.5 MHz to 100 MHz are described. The power amplifier circuits have power field effect transistor (FET) devices as output components and the FET devices are driven by bipolar transistor devices without frequency limiting components. The power amplifier circuits can be coupled in parallel and the coupled amplifier circuits can be operated in a push-pull mode of operation for increased power. The systems using these amplifier devices can operate in a Class A, B, C, D, E, F and S modes. In particular, a Class D amplifier system is described that uses the switching power amplifier circuits in the extended frequency range.

Apparatus and method for paralleling power field effect transistors in

An improved high frequency high power transistor assembly capable of delivering 600 watts or more at 100 MHz and higher without the need for water cooling is described. Four transistor die individually mounted on separate BeO ceramic isolators are installed in a recessed cavity in a copper base. The BeO isolators have metallized top surfaces which connect to the backside output contacts of the transistor die and extend toward the centerline of the cavity. They connect to a longitudally arranged input-output assembly centrally located over the center line of the cavity. The input-output assembly has a wrap-around electrode structure which brings the transistor output connections to the upper surface of the assembly for easy bonding to the output leads. The input to the individual die is via individual ballast resistors mounted on the input-output assembly, one per transistor, to provide transistor-to-transistor matching for more uniform current distribution.

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Phoenix, AZ, United States of America

Helge O Granberg