An Over-60dB True Rail-to-Rail Performance Using Correlated Level Shifting and an Opamp with 30dB Loop Gain

📋 论文概要

本文提出一种利用相关电平移位（CLS）技术，在仅30dB环路增益的运放下实现超过60dB真轨到轨性能的方法，解决了低电源电压下运放增益不足和输出摆幅受限的问题。

💡 主要创新点

• 提出相关电平移位技术，在不使用共源共栅器件的情况下显著提升运放有效增益和输出摆幅。
• 在0.18µm工艺下，仅用30dB环路增益的运放实现了超过60dB的轨到轨性能，突破了传统低电压设计限制。

🏷 关键词

📄 原文摘要

Finite opamp gain and output swing are two limitations for precision analog circuits. These limitations are especially serious at lower supply voltages where limited headroom prevents the use of cascode devices to improve gain. The magnitude of the problem is illustrated in Fig. 30.1.1 for a 2-stage opamp in a 0.18µm process. When each leg is biased at 1mA, the gain of the opamp is ~18dB per stage, therefore, when configured for a gain of 2, the overall loop gain is ~30dB. This gain decreases dramatically when the output is near the rails as the driven second-stage device enters the linear region. Note that with a loop gain of 30dB, the closed-loop gain is only 1.95V/V, and this poor gain is only maintained with more than 150mV of headroom. At best, one could expect about 5b performance with a useful swing of 0.6V in a traditional configuration. Technology scaling will not improve the situation. First, intrinsic

👥 作者与机构

B. Robert Gregoire, Un-Ku Moon

Oregon State University, Corvallis, OR