| The Cancellation Performance (CP) of cancellation loops, which constitute the feed-forward amplifier system, is investigated mathematically and the simulation results are given. The effects of amplitude imbalance, phase imbalance and delay mismatch on the cancellation performance of a cancellation loop are fully analyzed. It's shown that the delay matching is the most important factor to obtain a wide-band feed-forward amplifier.In applications of feed-forward linearization technique, the overall amplifier efficiency is significant concerned. Giving mathematical analysis and simulation results, the paper present two practical methods to optimize the efficiency of a feed-forward amplifier system.According as the analysis of third-order inter-modulation of high-power amplifiers, an innovative practical method to adjust the feed-forward amplifier system to optimize the performance of feed-forward amplifier system is described.The application of feed-forward linearisation to a 890-915MHz amplifier is described. Results are given for a series of two-tone inter-modulation distortion measurements. It is shown that a 25 dB improvement in the inter-modulation margin can be achieved. |
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