高精度光电编码器ASIC芯片信号读出电路设计

Signal Readout Circuit Design for A High-Precision Optical Encoder ASIC Chip

摘要:

为满足光电编码器信号读出电路在集成度、体积和分辨率等方面的设计要求,文章基于伪随机编码原理和莫尔条纹光信号理论,对增量式光电编码器和绝对式光电编码器的编码原理进行研究。设计并流片了一款基于增量式与伪随机混合编码方式的高分辨率光电编码器专用集成芯片,基于350nm CMOS工艺实现了光电探测器与读出电路的全集成。该芯片尺寸仅有4.6mm×3.5mm,分辨率可以达到22bit,在50kHz的信号周期下能同时产生精确的正弦和余弦输出信号,以及在2MHz的时钟频率下输出数字形式的伪随机码信号,满足系统的设计指标。

Abstract:

To meet the design requirements of integration, volume, and resolution for the signal readout circuit of optical encoders, this study analyzes the encoding principles of incremental and absolute optical encoders, based on the pseudo-random coding principle and Moiré fringe optical signal theory. A dedicated integrated circuit for high-resolution optical encoders, based on the incremental and pseudo-random mixed encoding scheme, is designed and fabricated. Utilizing a 350nm CMOS process, full integration of the photodetector and readout circuitry is achieved. The chip size is only 4.6mm×3.5mm, with a resolution of up to 22bit. It can simultaneously generate precise sine and cosine output signals within a signal period of 50kHz, as well as output digital pseudo-random code signals at a clock frequency of 2MHz, meeting the design specifications of the system.