Bandpass Filter and Oscillator ICs with THD < -140dBc at 10Vppd for Testing High-Resolution ADCs

📋 论文概要

该论文提出了用于测试高分辨率ADC的带通滤波器和振荡器集成电路，实现了低于-140dBc的总谐波失真（THD）在10Vppd输出下。解决了传统测试硬件THD不足且体积大的问题。

💡 主要创新点

• 设计了一种主动带通滤波器，可将中等精度正弦波的谐波衰减到-140dBc以下。
• 提出了基于正反馈环路的模拟振荡器，直接生成-140dBc THD的正弦波，适合高精度ADC测试。

🏷 关键词

📄 原文摘要

Indian Institute of Technology Madras, Chennai, India 1 2 The growing demand for high-resolution (18 to 20bit) precision ADCs has increased the need for very low THD (< -140dBc) testing hardware that can simultaneously characterize multiple ADCs cost-efficiently in a small form factor. One of the options is to use an active bandpass filter (BPF) to attenuate the harmonics of a medium-accuracy (THD~ -80dBc) sinusoid from a DAC or a bench-top generator. Another option is to generate a -140dBc THD sinusoid using an analog oscillator consisting of a BPF in a positive feedback loop with amplitude stabilization. In either case, the filter’s distortion must be kept below -140dBc at a 10Vppd output swing, which is the typical full scale of ADCs operating with a 5V supply. Among active filters, the second-order Tow-Thomas activeRC topology with opamp-based integrators provides the lowest distortion levels [1].

👥 作者与机构

Subha Sarkar1,2, Rajat Agarwal1, Nagendra Krishnapura2

Texas Instruments, Bangalore, India