Research And Design On L-band Suboptimum Class-e Power Amplifier

As one of switching-mode power amplifier(PA), class-E power amplifier have a broad application prospects due to their high efficiency and simple circuit structure. However, the traditional class-E PA have a shortcoming that its upper operating frequency is limited by the nonlinear output capacitance of the transistor. Therefore, how to improve its operating frequency limitation of the class-E power amplifiers has become an important research topic.Focus on this problem, the suboptimum technique is applied to analyze the class-E PA with concerning the duty cycle of switching voltage and current. The consequent results are a higher operating frequency and lower drain switching voltage. After detail analyzing the harmonic terminal of the PA, a novel circuit structure is proposed which shows a very good effect on harmonic suppression. Finally, the methods of the broadband design of the suboptimum class-E PA is studied, and the L band class-E PA is designed, fabricated and tested.The main points of works of this paper is as follows:1. The suboptimum design method for class-E is studied, and its influence is analyzed. This design method is applied to the class-E PA design, and through the analysis of simulation, the design method is verified.2. The harmonic terminals of class-E PA are analyzed, and a novel circuit structure with the affect of harmonic suppression is designed. Through the simulation analyzing of the specific circuit, the design is verified. A transmission-line suboptimum class-E PA with the affect of harmonic suppression is designed. Through the simulation and analysis of this PA, the feasibility of the design method is verified.3. The methods of the broadband design of the suboptimum class-E PA is studied, and an L-band broadband suboptimum class-E amplifier which has high efficiency is designed. In the design of input circuit and output circuit, using the extracting method of optimizing impedance can simplify the broadband matching; through an additional transmission-line and the low-pass filter network, the design can be simplify and the efficiency can be improved. Through the simulation and test of the broadband PA, the previous design methods are verified. Design, fabrication, and testing of this broadband suboptimum class-E PA have been finished. The optimization results show that: the op-erating frequency is 900~1500MHz(the relative bandwidth is 50%); the efficiency is greater than 70%; the gain flatness is less than ±0.5dB; the output power is greater than 40 dBm. At last, this paper completes the test data analysis and introduces the methods on the design improvement.The work of this paper has engineering reference value on the design of class-E PA in microwave band.