| As the best high-speed communication access technique, multicarrier technique requests wideband, high efficiency and excellent linearity performance for wireless communication systems. Doherty power amplifiers(DPA) have been widely used in the presence of modulated signals with high peak to average power ratio mainly for its high efficiency at large back-off power region. Furthermore, DPAs generally show relatively weak linearity for its working mechanism. Traditional power back-off linearization tech-nique is ultilized for comparable linearity while it’s at the loss of power and efficiency. Mainstream techniques like digital baseband predistorting and feed-forward is widely used while problems like more hardware consumption, larger size, increased complexity and lower system efficiency generate inevitably. Hence, high-performance DPAs design techniques that can satisfy needs requested by multicarrier communication technique is the focus and the difficulty of DPAs’ research. The output power that come from Carrier PA and Peaking PA are added after phase compensation. Hence, harmonics recycle and suppression can be considered as an entry point to design high-performance DPAs while the λ/4 conversion line in DPAs shows fairly weak harmonic rejection property which is against DPAs’ linearity and efficiency.First of all,a structure that consists of a pair of coupled line and capacitive dualport network was designed.On this basis, a wideband DPA that based on the structure to replace the λ/4 line in the traditional DPAs for harmonic rejection, phase compensation and impedance conversion is propsoed, fabricated and measured. In the 2.1~2.4 GHz band, the realized DPA delivered excellent drain efficiency at saturated and 6d B backoff region with saturated gain higher than 10.2d B. Compared with the traditional DPAs, the 3-rd intermoduation is notably improved by 20 d B, the largest AM-PM distortion is just 2.88o. And then, 5~6% drain efficiency improvement is achieved by introducing Defected Ground Structure into the structure that consists of coupled line and capacitive dual-port network for enhancing its harmonic suppression property. For further improve- ments of DPAs’ performance, a wideband DPA based on two pairs of coupled-line loaded with capacitive dual-port network is realized and measured. The proposed DPA delivered excellent performance in the 1.8~2.4GHz band with drain efficiency higher than 66.23% and 31% at saturated and 6d B power back-off region, respectively. Compared with the traditional DPAs, the 3-rd intermoduation was notalbly improved by about 22 d B.Meanwhile, an improved harmonic-control network was designed and applied in the DPAs’ design. And then, a wideband high-efficiency DPA based on the improved harmonic-control network and working in the 1.7~2.5GHz band for high drain efficiency performance is realized and measured either. As the measured results shows, the saturated gain is higher than 8.8d B and saturated drain efficiency is higher than 63.69%. Furthermore, the drain efficicy at 6d B OPBO region is between 36.9% and 60.65%. Compared with traditional DPAs, the realized DPA based on harmonic-control technique achieved the results of bandwidth extension and drain efficiency improved. Finally,a miniaturized Wilkinson power divider(WPD) that works in the 2~2.4GHz band was proposed.The proposed WPD employs a kind of special structure.The proposed WPD shows that, in a wide adjacent channel frequency range, the harmonic rejection property can be designed flexibly.By measuring the realized DPA and WPD in this work, the measured results agree with the simulated design basically, thus valifing the feasibility of design scheme and the validity of theoretical analysis in this work. |
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