United States Patent  [ii] Patent Number: 4,878,030
Vincze  Date of Patent: Oct. 31,1989
 LINEARIZER FOR MICROWAVE AMPLIFIER
 Inventor: Arpad D. Vincze, Los Altos, Calif.
 Assignee: Ford Aerospace & Communications Corporation, Newport Beach, Calif.
 Appl. No.: 112,852
 Filed: Oct. 23,1987
 Int. CI.* H03F 1/30; H03F 3/58
 U.S. CI 330/149; 330/43
 Field of Search 330/149, 43, 295, 124 R,
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Primary Examiner—Gene Wan
A microwave signal linearizer for a travelling wave tube amplifier (TWTA) provides for simple and flexible adjustment of a predistortion network suitable for independently compensating for a wide range of travelling wave tube amplifier-induced distortions. The linearizer or predistortion network is formed by three divided parallel passive microwave signal channels, the first channel having a coaxial microwave limiter diode network, the second channel having a variable attenuator for adjusting amplitude modulation (AM/AM) nonlinearity, and a third channel for adjusting amplitude modulation to phase modulation (AM/PM) nonlinearity. Signals directed to the first and second channels are combined in a 180° hybrid network to produce a difference signal which is directed through a difference channel to a 90° hybrid network. The signals through the third channel are directed to the 90° hybrid network where the difference channel and the third channel are combined and directed to an output channel for providing drive signal to a power amplifier, i.e., a travelling wave tube.
6 Claims, 3 Drawing Sheets