A 560 μ W, 6 fA/√Hz, 146 dB-DR Ultrasensitive Current Readout Circuit for PWM-Dimming-Tolerant Under-Display Ambient Light Sensors

IF 2 Q3 COMPUTER SCIENCE, HARDWARE & ARCHITECTURE

IEEE Solid-State Circuits Letters Pub Date : 2025-10-30 DOI:10.1109/LSSC.2025.3626378

Xiuzhi Zhao;Liheng Liu;Shi Chen;Tianxiang Qu;Qinjing Pan;Dan Li;Gan Guo;Zhiliang Hong;Jiawei Xu

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引用次数: 0

Abstract

This letter presents an ultralow-noise, power-efficient, and pulse-width modulation (PWM)-dimming-tolerant photocurrent readout circuit for under-display ambient light sensor (ALS). A transimpedance amplifier (TIA) with a feedback diode achieves G

$\Omega $

-level resistance and 6 fA/

$\surd $

Hz input current noise, enabling sub-pA resolution. Instability and noise folding are mitigated at low power through a signal-dependent auto-tracking zero for frequency compensation and a low-pass filter for high-frequency noise suppression. A 2-point calibration algorithm improves the linearity of the current-to-frequency (I2F) quantizer without incurring additional power. To extract ambient light in the presence of PWM dimming interference, the readout supports under-sampling, allowing digital cancellation of interference. Fabricated in 180 nm CMOS, the prototype achieves

$0.36~\rm pA_{pp}$

resolution, 146.3 dB dynamic range (DR), and a 206.3 dB

$\rm FoM_{DR}$

in 0.84 ms readout time, representing best-in-class performance. Optical ALS measurements under PWM dimming interference are experimentally validated.

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一种560 μ W、6 fA/√Hz、146 dB-DR的pwm耐调光显示环境光传感器超灵敏电流读出电路

本文介绍了一种用于显示下环境光传感器（ALS）的超低噪声、节能和脉宽调制（PWM）容光的光电流读出电路。带反馈二极管的跨阻放大器（TIA）可实现G $\Omega $级电阻和6 fA/ $ $ surd $ Hz输入电流噪声，从而实现sub-pA分辨率。在低功率下，通过信号相关的自动跟踪零频率补偿和低通滤波器的高频噪声抑制来减轻不稳定性和噪声折叠。两点校准算法提高了电流-频率（I2F）量化器的线性度，而不会产生额外的功率。为了在存在PWM调光干扰的情况下提取环境光，读数支持欠采样，允许数字消除干扰。该原型机采用180 nm CMOS制造，在0.84 ms的读出时间内实现了0.36~\rm pA_{pp}$分辨率，146.3 dB动态范围（DR）和206.3 dB $\rm FoM_{DR}$，具有同类最佳性能。实验验证了PWM调光干扰下的光学ALS测量结果。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

IEEE Solid-State Circuits Letters Engineering-Electrical and Electronic Engineering

CiteScore

4.30

自引率

3.70%

发文量