Empirical Modeling of Microwave Devices：微波器件的实验建模.pptVIP

Power amplifier efficiency enhancement techniques Christian Fager Microwave Electronics Laboratory Department of Microtechnology and Nanoscience, MC2 Chalmers University of Technology 2006-10-16 Outline Background Why is high efficiency important? Switched mode power amplifiers Why are SMPAs more efficient than traditional PAs? Device technologies Which devices are used to realize SMPAs? Transmitter architectures How can SMPAs be used to transmit modulated signals at high efficiency? Summary Background Why high efficiency is important Increased power consumption Battery cost Heavier power supplies Electrical power expenses Environmental incentive Further multiplied by need for extra cooling Deterioration of semiconductor reliability Example: Radio base stations Total energy consumed by base stations in Sweden: 1.2 - 2.1 TWh/yr Energi from of a Barseb?ck size nuclear reactor: 4 TWh/yr... The final power amplifier handles the highest power levels and dominates the total power consumption Power amplifier efficiency enhancement is very important! Dynamic input signal variations 3G base station: Transmitted WCDMA signal The modulation creates dynamic signal power variations Traditional linear PA operation The peak output power is determined by its saturation PA efficiency is maximum close to saturation Operating it into compression results in severe distortion The total PA efficiency is weighted by the signal input power probability density function For this case: Peak PAE = 27%, total average PAE = 15% How can more efficient PAs be realized??? Switched mode power amplifiers Why are SMPAs more efficient than traditional PAs? Traditional power amplifiers Transistor is used as variable current source Typically biased in class AB operation, where linearity and efficiency trade-off is most favorable Simultaneous voltage and current Dissipation across the device Limits practical efficiency to 50% How can the voltage×current overlap be minimized? Sw