基于动态可修调误差放大器的高精度Buck-Boost转换器设计方法

传统的修调方案是通过改变电阻反馈网络的反馈系数来对系统的输出电压进行修调，这种针对于特定输出电压下的反馈电阻修调的方法无法保证配置不同输出电压时的精度. 针对上述问题，本文通过分析环路的工作特点，从固定工作点的误差放大器入手，提出基于动态修调误差放大器电流的高精度Buck - Boost转换器设计方法. 基于0.18 μm BCD工艺对提出的方法进行了具体电路设计与物理实现验证.结果表明，修调电流可以将输出电压±40 mV的输出电压误差降低到±1.83 mV，输出电压精度可以达到0.045 7 %；在输出电压误差满足≤5 mV时，满修调时可实现最大误差62.83 mV的修调.相较于传统结构，修调电压的精度受PVT变化影响较小，极大地改善了系统的输出精度，该方法已在一款Buck - Boost型转换器中得到成功应用. 

Design Method of High Precision Buck-Boost Converter Based on Dynamically Trimming Error Amplifier

The traditional modification scheme is to trim the system by changing the feedback coefficient of the resistance feedback network. However, the method, arranged for the feedback resistance trimming at a specific output voltage, can not ensure the precision of different output voltage configurations. To solve the problem, analyzing the working characteristics of the loop and starting at fixed operating point of the error amplifier, a design method of high-precision Buck-boost converter was proposed based on dynamic adjusting of the current of the error amplifier. Based on 0.18 μm BCD process, the circuit design and physical implementation were carried out to verify the proposed method. The results show that the output voltage error can be reduced from ±40 mV to ±1.83 mV, and the output voltage accuracy can reach 0.0457%. When the output voltage error is less than or equal to 5 mV, the maximum error is 62.83 mV. Compared with the traditional structure, the precision of the modified voltage is less affected by the change of PVT, which greatly improves the output accuracy of the system. The method has been successfully applied in a Buck-Boost converter.