Analog integrated circuit design has as integral parts both analytical reasoning and numerical validation in the process from topology construction to sizing. Given a circuit topology, different circuit sizing results can be obtained from different processes of sizing inference. Sizing methods by simulation-based numerical searching have been a continuously studied subject. However, almost all approaches in this category require an overwhelming number of circuit simulations to arrive at an optimized sizing result. On the other hand, many published manual sizing methods by using the conventional device equations also require repeated SPICE simulations to correct the equation-based sizing results. This paper proposes a systematic gm/ID-based initial sizing method specifically customized for designing multiple-stage operational amplifiers (Op Amps). A main feature of the proposal is to use circuit-level design equations as constraints on the gm/ID table lookup method to substantially reduce the uncertainty in the sizing calculations. As a result, a significant amount of SPICE based correction work can be reduced to complete an initial sizing. The proposed sizing procedure includes a few regular sizing rules customized to the configuration of multi-stage Op Amps. We validate the proposed sizing method by application to several multi-stage Op Amp examples with a capacitive load or Miller compensation. Simulations have justified that the produced initial sizing results can achieve most of the prespecified design targets.

模拟集成电路设计在从拓扑构造到尺寸确定的整个过程中都具有分析推理和数值验证这两个组成部分。给定电路拓扑，可以从不同的尺寸推断过程中获得不同的电路尺寸调整结果。通过基于模拟的数值搜索来确定尺寸的方法一直是一个不断研究的课题。但是，此类中的几乎所有方法都需要大量的电路仿真，才能获得最佳的尺寸确定结果。另一方面，许多通过使用常规设备方程式发布的手动调整尺寸方法也需要重复进行SPICE仿真，以校正基于方程式的尺寸调整结果。本文提出了一种基于系统的基于gm / ID的初始大小确定方法，该方法专门针对设计多级运算放大器（Op Amps）而定制。该建议书的主要特征是使用电路级设计方程作为对gm / ID表查找方法的约束，以大大减少尺寸计算中的不确定性。结果，可以减少大量基于SPICE的校正工作，以完成初始调整。建议的尺寸调整程序包括一些针对多级运算放大器的配置而定制的常规尺寸调整规则。通过将其应用于具有电容负载或Miller补偿的几个多级运算放大器示例，我们验证了所提出的尺寸调整方法。仿真证明，所产生的初始尺寸确定结果可以实现大多数预先指定的设计目标。