JSSC 2023第3期RF & Wireless0.18μmNeural Network Accelerator

A1 . 8 - G Input-Impedance 0.15-μV Input-Referred- Ripple Chopper Ampliﬁer With Local Positive Feedback and SAR-Assisted

一种采用局部正反馈环的斩波放大器，实现高输入阻抗和低输入波纹。

0.18μm CMOS, 5V, 1.07mA, 1.8GΩ输入阻抗, 0.15μV输入波纹

斩波放大器电流反馈仪表放大器局部正反馈低噪声低偏移

▸创新点1：局部正反馈环（LPFL）技术通过增益无关的阻抗提升，显著提高了输入阻抗至1.8 GΩ，同时保持低噪声和低偏移特性，属于电路结构创新。

▸创新点2：采用无源高通滤波器有效抑制了传统斩波放大器中的纹波问题，输入参考纹波降低至0.15 μV，属于噪声抑制方法创新。

▸创新点3：SAR辅助偏移校准技术结合被动高通滤波，实现了高精度偏移校准（输入偏移低至4 μV和2 μV），属于系统级校准创新。

▸创新点4：多路径电流反馈仪表放大器（CFIA）可重构为通用运算放大器（OPA），兼具高电源效率（最高GBW/I_SUPPLY）和低噪声密度（39 nV/√Hz和20 nV/√Hz），属于多功能架构创新。

Abstract

This article presents a chopper-stabilized multipath current-feedback instrumentation ampliﬁer (CFIA) that can also be reconﬁgured to a general-purpose operational ampliﬁer (OPA). By utilizing a local positive feedback loop (LPFL), both the CFIA and the OPA beneﬁt from gain-independent impedance boosting while retaining the merits of chopping, i.e., low noise and low offset. In addition, the chopping-induced ripple, one of the main issues of conventional chopper ampliﬁers, is suppressed by a passive high-pass ﬁlter with the S AR-assisted offset calibration. The prototype IC is implemented in a 0.18- μm CMOS process and draws 1.07-mA current from a 5-V supply. The chopper CFIA exhibits the minimal input impedance of 1.8 G and the maximum input referred ripple of 0.15 μV (ten samples for both tests). These correspond to at least 1.13× and 1.3× improvements on the state-of-the-art IAs, res pectively. The CFIA and the OPA also achieve excellent power efﬁciency (the highest GBW/I SUPPLY), competitive input offset (4 and 2 μV), and input noise density (39 and 20 nV/ √ Hz).