New Technique for Low Intermodulation and High-Efficiency RF/Microwave Amplifiers

Tez Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: The University of Westminster, Engineering, Electrical and Electronics, İngiltere

Tez Danışmanı: Djuradj Budimir

Tezin Onay Tarihi: 1997

Tezin Dili: İngilizce

Özet:

A new technique for reducing third order IM distortion in a non-linear amplifier has been proposed. Amplifiers offer maximum efficiency at the saturation point, but at this point they are-in the non-linear mode. If two signals at different carrier frequencies are incident at the input of an amplifier, due to the nonlinearity, these signals will interact with each other, and the output will contain additional signals at all combinations of sum and difference of these fiundamental frequencies. These additional signals are the IM products. The iniection of the second harmonics in the amplifier together with the fimdamental signals will produce additional IM products having the same frequency as the original third order IM products at the output. By proper selection of phase and amplitude of the injected second harmonics, it is possible to make the third order IM products produced by the second harmonics and the original third order IM products out of phase and equal in amplitude. As a result third order IM products will be eliminated, in principle. Theory and simulation results obtained during the project at 2.5 GHz are presented, which supports the suggestion.