This paper describes the design of a touch screen panel (TSP) readout IC having an in-band noise immunity. The proposed IC employs a cascaded spread spectrum TSP driving scheme combining chirp spread spectrum (CSS) and pseudo-random (PR) orthogonal sequences. The CSS shows the 12-dB spread gain prior to an application of PR sequences, resulting in total -24-dB in-band noise immunity. The proposed IC adopts trans-impedance amplifier (TIA) with differential current scaler (DCS), providing dynamic range of an analog front-end (AFE) only for a capacitive change from touches. The IC was fabricated in a 0.13- $\mu \text{m}$ standard CMOS. The measurement result shows that the proposed AFE achieves 54.2-dB SNR and 240-Hz scan rate with 11.5-mW power consumption. The readout IC was demonstrated with 5.3-inch $31\times16$ TSP.

中文翻译：

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用于有源矩阵 OLED 显示器可变刷新率的 -24 dB 带内抗噪互电容读出系统

本文介绍了具有带内抗噪能力的触摸屏面板 (TSP) 读出 IC 的设计。所提出的 IC 采用级联扩频 TSP 驱动方案，结合了线性调频扩频 (CSS) 和伪随机 (PR) 正交序列。在应用 PR 序列之前，CSS 显示了 12-dB 的扩展增益，从而导致总共 -24-dB 的带内噪声抗扰度。建议的 IC 采用具有差分电流缩放器 (DCS) 的跨阻放大器 (TIA)，仅针对触摸电容变化提供模拟前端 (AFE) 的动态范围。IC 以 0.13- $\mu \text{m}$ 标准CMOS。测量结果表明，所提出的 AFE 实现了 54.2-dB SNR 和 240-Hz 扫描速率，功耗为 11.5-mW。读出 IC 用 5.3 英寸 $31\times16$ TSP。