采用有源电容倍增器改善开关电容DC-DC变换器的性能

研究了开关电容DC-DC变换器输出电压与电容的关系,分析了变换器输出电压波纹产生的原因.针对变换器中大电容难集成的问题,提出了一种基于跨导放大器和第二代电流传输器的有源电容倍增器的新型拓扑结构.该电路只用较少的元件就可以实现开关电容变换器中的浮地和接地电容.以二阶开关电容DC-DC变换器为例,用PSPICE软件分别对采用了有源电容倍增器的新型结构和传统结构进行了仿真.结果显示,基于有源电容倍增器的开关电容变换器仅用100pF电容就等效了200nF电容的输出性能,而且具有更低的输出电压波纹.

Improving Performance of Switched-Capacitor DC-DC Converter with Active Capacitance Multiplier

The relationship between output voltage and capacitance in switched-capacitor DC-DC converter was investigated,and the reasons for output voltage ripple in the converter were analyzed.Aiming at the difficulties in fabricating large capacitors in the converter,a new topology of active capacitance multiplier based on OTA and CCⅡ was proposed.This circuit realized the functions of floating capacitor and grounded capacitor in switched-capacitor converter with fewer components.Taking second-order switched-capacitor DC-DC converter as an example,we simulated output performances of traditional and novel circuit structures respectively by software PSPICE.The results show that the performance of novel converter with 100pF capacitors is equivalent to the conventional converter with 200nF capacitors.And also the converter based on active capacitance multiplier has much lower output voltage ripple.