| In this thesis, the method to implement the 1MHz bandwidth envelope tracking supply is studied, for it can solve the contradiction between the linearity and efficiency in modern RF power amplifier. After the selection of the switch and linear combinated topology, in this paper, the two control strategies for the topology, the hysteresis control and the current feedback control, are proposed. Then the interleaving technology in the current feedback control is analyzed. Based on the above analysis, the method to implement the 1MHz bandwidth envelop tracking supply is that using the current feedback control with the multi-channels interleaving parallel, and the multi-channels interleaving parallel can be implemented with Staggered sawtooth method.In the hysteresis control, the slew rate theory is refered. In this theory, the operation of the system can be divided into two parts: the small signal linear region and the large signal nonlinear region. Then the average switch frequency is given. A experiment with 147kHz average switch frequency is designned for the slew rate theory, and the characteristics of hysteresis current control is gotten.In the current feedback control, the priciple of it is described. Then a experiment which has the bandwidth of 34kHz with 134kHz switch frequency is designed and the control strategy is tested at input DC signal conditions. At last it is expensed to two channels interleaving parallel with 67kHz switch frequency, and tested with DC signal, small envelope voltage, output peak power 18W and 32W when the control parameters is unchanged. The characteristics of the current feedback control is gotten too.Based on above two experiments, the characteristics of the two controls is compared. Finally, the three methods to implement the intealeaving is discussed. And the Staggered sawtooth method is best for the current feedback control, then the 6 channels 1MHz staggered sawtooth generating circuit is simulated. That is the basis to implement the 1MHz bandwidth envelope tracking supply. |
