| 摘要 |
Two identical high power amplifiers (31, 32) in a quadrature combined configuration function both as the main amplifier and as the error amplifier. A first loop is provided to subtract a properly scaled and delayed sample of the amplifier input spectrum from a scaled and phase shifted sample of its output spectrum which contains intermodulation distortion. The result of this subtraction (if the samples are maintained at the same amplitude and 180 degrees out of phase) is a signal rich in the intermodulation products of the amplifier. A differential phase-amplitude comparator (58) which compares the signals prior to and after amplification and generates control signals for amplitude and phase trimmer (42, 44) for the signal prior to the amplifier and thus maintains the required equal amplitude and 180 degree phase relationship required for carrier cancellation. A second loop is provided to reduce distortion of the error signal due to effects of the amplifier.
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