基于平衡态的动态比较器失调电压分析和设计优化

本文提出了一种基于平衡态的动态比较器失调电压分析设计技术。以两支路电压电流相等的平衡态为分析基础,通过在复位电压跳变时刻引入补偿电压的方法,逐一分析了动态比较器各晶体管参数对总体失调电压的影响,建立了失调电压的数学模型;采用Chartered 0.18um1P6M工艺对Lewis-Gray型动态比较器进行了电路和版图设计,并利用可快速提取失调电压的定步长仿真方法对其失调电压进行了仿真,结果表明所提出的分析方法可以相对准确的估算失调电压。以该分析方法为基础,本文还提出一种基于总体失调电压影响权重的晶体管分组优化方法,在保证总体面积不变的条件下,可将失调电压有效降低50%以上。经流片测试结果表明,本文所提出的分析和优化方法可应用于高速高精度系统中比较器的设计。

Analysis and optimization of dynamic comparator offset voltage based on equilibrium state

An analysis method based on equilibrium state is proposed to analysis the offset voltage of dynamic comparators.It mainly features on the establishment of two branch current equilibrium state by inserting an input compensation voltage when the reset signal changes.Based on these,the mathematic model containing each transistor’s effect on total offset voltage can be analyzed.For verification,a Lewis-Gray comparator is designed in the circuit and layout level by the Charter 0.18 standard processing.A fixed step-size stimulation method is used for fast extraction of the offset voltage.The simulation result shows that the estimated offset using proposed method can accurately agree with actual value.Based on this method,we also suggest a transistors effect-weight-grouping optimization design to reduce the offset voltage.Maintaining the same area consumption,the offset after optimization can be cut by 50%.In a word,the proposed method is suitable to comparator design in high speed high resolution system.