The Research & Design Of High-Efficiency Synchronous Rectification Buck DC/DC Conversion

Recently, DC/DC switching converters have been widely used in communication systems, computers and consumer electronic products, etc. To improve the performance of DC/DC switching converters, high efficiency, high precision and high integration are the key in the design.Firstly, the basic principle buck DC/DC switching converter is introduced, and the various sources of power loss and the synchronous rectification technology are further analyzed. Then, the critical circuits are designed, including compensation ramp circuit, error amplifier/compensation network, PWM comparator, current-sensing circuit, synchronous rectification driving circuit and continuous-current sensing circuit, etc.a novel built-in current-sensing circuit and a synchronous rectification driving circuit are designed, thus the current-mode pulse-width modulation technology and the synchronous rectification technology are integrated skillfully. Consequently, the efficiency, precision and integration of the DC/DC converter are improved effectively.Based on the 0.35um 3.3V CMOS model, the whole circuit is simulated. The simulation result shows that the conversion efficiency is up to 91%, the output ripple voltage is only 7mV, the load regulation is ? 0.428(% / A) and the line regulation is 0.26(% / V). The specifications required are attained.