A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth. Experimental results are presented for IMT-2000 frequency band. The center frequency of the feedforward amplifier is 2140 ㎒ with 60 ㎒ bandwidth. When the average output power of feedforward amplifier is 20 Watt, the intermodulation cancellation performance is more than 28 ㏈. In this case, the output power of feedforward amplifier reduced 3.5 ㏈ because of extra delay line loss and coupling loss The feedforward amplifier efficiency is more than 7％ for multicarrier signals.
Abstract
1. Introduction
2. Technologies for Nonlinear Compensation
3. Feedforward Linearization System Design and Experiment Result
4. Conclusion
References
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