A 21b ±40mV Range Read-Out IC for Bridge Transducers

📋 论文概要

本文提出了一种用于桥式传感器的21位±40mV范围读出IC，通过三级电流反馈仪表放大器与增量ΔΣ调制器结合，实现了低噪声、高精度和低漂移，解决了传感器系统在温度变化下保持精度的问题。

💡 主要创新点

• 采用三级电流反馈仪表放大器（CFIA）结构，有效降低热噪声和1/f噪声。
• 结合增量ΔΣ调制器，实现21位高分辨率读出，同时保持极低的失调和增益漂移（几ppm/°C）。

🏷 关键词

📄 原文摘要

Precision thermocouples and bridge transducers such as strain gauges and thermistors require read-out ICs with low noise, high accuracy and low drift. In such applications, the sensor and the read-out IC (ROIC) are usually calibrated as a single system, and so in addition to low thermal and 1/f noise, the ROIC should exhibit very low offset and gain drift (a few ppm/°C) to maintain system accuracy over temperature. This paper describes a 21b ROIC that meets this challenge. The ROIC consists of a 3-stage current-feedback instrumentation amplifier (CFIA) and an incremental ΔΣ modulator (Fig. 6.4.1). The CFIA provides the high input impedance required for accurate bridge readout and relaxes the requirements on the ADC’s noise and offset. Its closed-loop gain is given by (Gm3/Gm4)(R1+R2)/R1, which, if Gm3 and Gm4 are well-matched, can be accurately set by the external resistors R1 and R2. The 1st and 2nd stages of the CFIA (Fig. 6.4.2) are chopped to achieve low offset

👥 作者与机构

Rong Wu, Johan H. Huijsing, Kofi A.A. Makinwa

Delft University of Technology, Delft, The Netherlands