Amplifiers – With plural amplifier channels – Redundant amplifier circuits
Patent
1997-11-25
1999-10-12
Mottola, Steven J.
Amplifiers
With plural amplifier channels
Redundant amplifier circuits
330126, 370480, H03F 368
Patent
active
059660481
ABSTRACT:
Amplifier-induced intermodulation distortion (IMD) is reduced by encoding a multi-frequency input composite signal into multiple encoded signals that vary from each other in their power amplitudes as a function of frequency, amplifying the encoded signals, and then decoding them in a complementary fashion so as to differentiate between the amplified signal components and the IMD components. The amplified signal components are coherently combined to separate them from the IMD components, which are incoherently combined. The input signal is preferably encoded by dividng it into multiple divided signals, introducing relative phase shifts between the divided signals that vary as a function of frequency, and combining the divided and phase shifted signals with each other in a Butler matrix prior to amplification. The phase shifts are introduced by means of time delays that are preferably equal to integer multiples of 4.PI. divided by the input signal bandwidth.
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Linearized transponder technology for satellite communications, Part I: Linearizer Circuit Development and Experimental Characterization, D. Cahana et al, COMSAT Technical Review, vol. 15, No. 2A, Fall 1985, pp. 277-307.
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COMSAT Technical Review, vol. 4, No. 2, Fall 1974, The Butler Matrix Transponder, W. A. Sandrin, pp. 319-345.
IEEE Journal of Solid-State Circuits, vol. SC-9, No. 6, Dec. 1974, A Wide-Band Feedforward Amplifier, R. G. Meyer et al, pp. 422-428.
Grunebach Georgann S.
Hughes Electronics Corporation
Mottola Steven J.
Sales M. W.
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