折叠运算放大器频率补偿

Folding Operational Amplifier Frequency Compensation

应用负反馈可以改善电路系统的性能,但是为了实现负反馈的优点,我们首先必须得确保电路不存在振荡,并且使电路处于稳定的工作状态。针对高增益折叠运算放大器提出了一种新的频率补偿优化算法。即,首先通过应用一个并联电容在一定程度上实现主极点的补偿,然后应用“桥梁电容”进一步实现主极点的补偿优化。其特点是利用“桥梁电容”在电路传输函数中引入一个零点来提高电路的带宽与相位裕度,从而优化电路的频域特性,降低电路的“过冲”,提高电路的性能。0.8μm B iCMOS工艺条件下,利用Cadence实现了设计的验证与仿真。

The performance of the system can be improved by applying negative feedback technique. However, in order to realize the merits of negative feedback technique, we must make sure that there will not exit the possibility of oscillation ,and make the system stabilized. This paper proposes a new method of frequency compensation for the high gain folding operational amplifiers. Firstly, a parallel capacitor was applied to realize the dominant pole compensation to some extent. Then, a ＂bridge capacitor＂ was applied and further realized the dominant pole compensation. It has been shown that the ＂bridge capacitor＂ could produce a zero in the transfer function and result in a wider bandwidth and phase margin. This improvement led to a good performance of the high gain folding operational amplifiers. Finally, we implemented the design verification and simulation by applying the 0.8μm BiCMOS technology.