Research On Tracking Sources Based On Multilevel Voltage And Current Sources

A kind of Tracking Source is proposed to improve the efficiency of RF amplifier.Two main methods EER and ET both need the high-frequency high-precision TrackingSource (also known as the Envelope Amplifier). According to the research on literatures,the designs of Tracking Source are summarized into two main categories includingfilter-output or linear-circuits-output each has its own supports. Strengths andweaknesses are judged by circuit principle rather than by the results stated in theliterature, which avoids impact of the level of technology or the age difference.A ‘linear power amplifier with switching circuit compensated’ scheme is selected.Based on the multi-level idea, a multilevel current source is proposed which can reducethe switching frequency. Then the multi-level current sources and multi-level voltagesources hybrid compensation is proposed which can significantly reduce the powerlosses of the linear power amplifier, which improve the overall efficiency.A mathematical model based on the probability density function was proposed tocalculate the efficiency improvement. Uniformization, Visible Graphical, ProbabilityDensity Function and Multi-step Integration compose the model. After the PartialDifferential the Maximal Efficiency in each strategy can be gotten. In addition, a similardiscrete model is also proposed for practical and computer calculation.Details of the designing of ‘multi-level voltage and current mixed-compensatedlinear amplifier topology’ are introduced. Above all, multilevel current source isdesigned based on the independent Buck-Boost topology, which can generate aladder-like current source. Linear amplifier schemes are compared, then choosing thelinear RF N-MOS to get a high-frequency-large-power A-class amplifier. Severalalternative voltage source schemes are analysed. In controller design, all-open-loop andcurrent-closed-loop are two basic strategies.The paper first introduces the two reiteration experiments to compare filter modeand linear-output mode. Then test the multi-level current source topology to confirmthat the current source compensation can greatly improve efficiency. Followed by amulti-level tracking prototype test results, to achieve a tracking frequency of1MHz andonly1/2losses in linear stage.At last the Tracking Source Based on Multilevel Voltageand Current Sources is teseted, which achieve a tracking frequency of500kHz and only1/6losses in linear stage.