| As the development of wireless communication technology, various communication services facilitated daily life, but the frequency spectrum congestion become more and more serious, modulation method with high efficiency on frequency is a good solution for this situation. This modulation method depends on high linearity of the system, makes the research on high linear amplifier very important.In this article the Feedforward linearization method that can enhance the OIP3 is introduced, the relationship between the mismatch of the amplitude and phase in Feedforward structure and the cancellation of the signal is analyzed and is described in mathematical. The circuit structure of Feedforward is simulated and proved it can improve OIP3. Balanced amplifier that can significantly suppress the second-order distortion is analyzed and simulated.A new hybrid structure is provided as the plan for this paper, in which the core amplifier is constituted a Feedforward amplifier then form into balanced amplifier. ATF54143 is selected as the core amplifier and formed the final product. A linearity test platform is built with existing instrument, the product is tested. OIP3 is enhanced 7.55~10.55dBm, and OIP2 is improved 30.4~34.2dBm; the requirements target is achieved; the hybrid structure is proved useful in linearity enhancement. |
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