| The current wireless communication systems have made significant progress towards multi-band and multi-carriers for high-data-rate applications. Due to this background, the dual-band and wide band RF power Amplifier applied in the transmitter of wireless base station has become a hot research issue. This thesis explores the design method of Dual-band Doherty Power Amplifier based on the study of Passive components. Major works are listed as follows:(1) The Dual-band Passive components are the basement for the Dual-band Operation. We design the Dual-band impedance matching network, Dual-band offset-line, Dual-band power divider based on the conventional T-shaped and ?-shaped micro-strip. These networks are the important part of the Dual-band Doherty Power Amplifier.(2) This thesis introduces a new dual-band matching network, including the dual-band stub loaded line and the expanded T-shaped micro-strip which has the different equal characteristic impedances for the two working frequencies. This proposed matching network matches any arbitrary reflection coefficient seen by the active device at two uncorrelated frequencies to the standard 50 ? load.(3) This thesis introduces a kind of dual-band phase delay line which is suit for the Offset-line of Doherty Power Amplifier. This circuit offers the phase we want at the two working frequencies and the equal characteristic impedance is 50 ?.(4) This thesis summarizes the method of designing a Dual-band Doherty Power Amplifier including the simulated and measured results. We compare the different method of every part of the Doherty Power Amplifier. Finally, we design and realize the dual-band Doherty Power Amplifier based on the CREE CGH40010 and achieve over 10 W output power, 41% and 35% of 6dB Back-off efficiency respectively at 1600 MHz and 3500 MHz. |
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