Appearance of spurious signals in a traveling-wave amplifier

Nonlinearities in the transfer characteristic of a traveling-wave amplifier (TWAMP) are examined with attention given to: amplitude and phase transfer characteristics, appearance of spurious signals in transmission of a set of signals via TWT, and use of a correcting circuit to compensate for the nonlinearity. Optimization of the transfer characteristic by judicious choice of operating point and of a programmable correcting circuit is discussed, with emphasis on linearization of the choice of operating point and adaptive linearization circuitry. Intermodulation, feedforward, phase predistortion, and TWAMP weight penalties (for TWAMP installation aboard a satellite) are discussed.