摘要
An s-domain analysis of the full dynamics of the pole-zero pair (frequency doublet) associated with the broadly used CMOS active-cascode gain-enhancement technique is presented. Quantitative results show that three scenarios can arise for the settling behavior of a closed-loop active-cascode operational amplifier depending on the relative locations of the unity-gain frequencies of the auxiliary and the main amplifiers. The analysis also reveals that, although theoretically possible, it is practically difficult to achieve an exact pole-zero cancellation. The analytical results presented here provide theoretical guidelines to the design of CMOS operational amplifiers using this technique.
An s-domain analysis of the full dynamics of the pole-zero pair (frequency doublet) associated with the broadly used CMOS active-cascode gain-enhancement technique is presented. Quantitative results show that three scenarios can arise for the settling behavior of a closed-loop active-cascode operational amplifier depending on the relative locations of the unity-gain frequencies of the auxiliary and the main amplifiers. The analysis also reveals that, although theoretically possible, it is practically difficult to achieve an exact pole-zero cancellation. The analytical results presented here provide theoretical guidelines to the design of CMOS operational amplifiers using this technique.
