Td-scdma High Efficiency F Power Amplifier Design And Implementation

By the end of2011, the global number of mobile subscribers has broken6.0billion.Meanwhile the user needs are becoming increasingly diversified, followed by thefull-scal commercialization of3G standard of large capacity and high data rate. As oneof the3G standard, TD-SCDMA, with own intellectual property, has expand thecommercialization process throughout the country. And the evolution of technology,LTE, also has achieved initial success.As one of the important components of the transmitter end, the RF power amplifierconsumes most of the power of the transmitter. In particular, in the case of the highcommunication rate and a higher peak to average power ratio (PAPR) of TD-SCDMAsignal, in order to meet a certain quality of the signal, power amplifier usually works inthe power fallback region, and its efficiency is much lower, more power loss. Therefore,improving the efficiency of the power amplifier, not only help to improve thetransmitter efficiency and reduce power consumption, but also protect the environmentand achieve sustainable development.Class F amplifier is a high-efficiency power amplifier based on the harmonic filtercircuit, to improve efficiency by changing the drain voltage and current waveforms.Ideally, class F amplifier has ideal open and short terminals. The drain voltage andcurrent waveforms do not overlap, and the drain efficiency can reach100%. In theactual circuit, the parasitic parameters of the power tube have a greater impact on theefficiency of the class F amplifier. Selecting less influence of the parasitic parameters ofGaAs/GaN power transistor and the right matching network, conducive to reduce itsimpact and improve the efficiency of class F power amplifier.In this paper, high efficiency power amplifier was as the research object. First, thecurrent technology status of high efficiency power amplifier such as class D, E, F andDoherty structure were described, and the design of the class F power amplifier wasdiscussed in detail. Then, combined with related project demand, a4W GaN device,namely Nitronex’s NPTB00004, was selected and designed a class F power amplifier inthe frequency range of2300MHz~2400MHz. Finally, the performance of the driveramplifier and the class F amplifier was simulated by ADS software, and the printedcircuit board was designed by Altium Designer, and the performance of amplifiers weretested with one tone and TD-SCDMA carrier signal respectively.Tested with one tone signal, achieved Power Added Efficiecy (PAE) of71.6%with anoutput power of37dBm; Tested with TD-SCDMA carrier signal, achieved PAE of58.7%with an output power of34dBm, and got Adjacent Channel Leakage Ratio(ACLR) of19dBc without Digital pre-distortion (DPD). At the end of the article, dosomething outlook for the future research, such as the design saturated Doherty.