| The rapid development of communication technology cannot leave the support of transceiver. The performance of RF power amplifier which is the core component of the transmitter has a huge impact on the whole system of hardware. The ever-changing wireless communication technology put forward more and more stringent requirements on the RF power amplifier. The efficiency and linearity, as the most key indicators of RF power amplifier, has been the breakthrough of the RF power amplifier technology development. Dual-band power amplifier could operate at two separate frequency, and Doherty power amplifier on efficiency has incomparable advantage over other structure of the power amplifier, which makes the dual-band power amplifier and Doherty amplifier become the current hot spot.This thesis mainly studies the multi-band power amplifier and the Doherty amplifier which has great advantage, and on this basis using GaN(Gallium Nitride) and LDMOS(Laterally Diffused Metal Oxide Semiconductor) tubes to complete the dual-band balanced and Doherty power amplifier design. The principal contributions and innovation of this paper include:1. First of all, the topic research background and significance of this paper are discussed and analysis, and then we state the semiconductor technology of the power tube which plays a decisive role in the development of the RF power amplifier in this paper, finally the development of the novel balanced power amplifier and harmonic suppression Doherty power amplifier are introduced.2. Put forward a new type of dual-band balanced RF power amplifier.The structure is based on a kind of branch line coupler which can terminate any real load .It is realized that matching the impedance of the transistor packaging reference surface from load-pull to the real impedance under two frequency, because the real impedance is not need strict 50 ohms, so double-frequency matching structure has been greatly simplified.3. In order to solve the shortcoming of traditional Doherty power amplifier in harmonic suppression, this paper proposes a novel Doherty power amplifier with harmonic suppression. Implementation method is mainly considering that if the output matching structure is not low pass,there will be a lot of harmonics. So we use parallel double transmission line which has harmonic suppression effect to equivalent substitute the 90 degrees impedance transforming line after Doherty power amplifier compounding, achieving good harmonic suppression.This thesis design and implement a new dual-band balanced power amplifier and a harmonic suppression Doherty power amplifier. The dual-band balanced power amplifier of the second frequency points while appeared deviation, but it still show that the performance of double frequency, can be used in many frequency wireless communication system. Harmonic suppression Doherty power amplifier using the harmonic suppression characteristic of the dual transmission line to filter the output harmonic components. It greatly improves the linearity of the power amplifier, which has obvious advantages over traditional Doherty power amplifier. |
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