为了满足光刻机工件台超精密运动控制系统对位移测量的需求，本文提出了基于FPGA的BiSS-C协议解码方法，并针对该方法进行了电路设计以及实验验证。首先，研究了BiSS-C协议内容，就其组网方式和帧格式做了详细的介绍。然后，针对绝对式编码器解码要求，利用FPGA拓展性好、灵活性高等特点，通过状态机，设计了绝对式编码器的数据传输电路，实现了BiSS-C协议的译码功能，并采用CLE-AA容栅尺进行了应用验证。最后，进行了与增量式光栅尺的对比校准实验。实验表明，容栅尺绝对式编码器可实现10 kHz的传输速率，运动误差在±5 μm之内，其可靠性与准确性满足超精密运动控制系统的粗定位要求。

In order to meet the displacement measuring requirement of the lithography machine wafer stageultra-precision motion control system, a BiSS-C protocol decoding method has been proposed, which is based on FPGA. The circuit design and experimental verification are carried out as well. Firstly, the BiSS-C protocol is analyzed and its configuration and data frame are presented in detail. Secondly, because of its characteristics of powerfulness and flexibility, FPGA has been used to realize the decoding function. The circuit to transmit the data of absolute encoderis is designed and applied on the CLE-AA grating-shape capacitive encoder. Finally, a comparison with the relative encoder of grating sensor is carried out. Experimental results indicate that the transmit rate of absolute encoder of the capacitive sensor is up to 10 kHz with the error limiting in ±5 μm. Its accuracy and reliability can satisfy the requirement of ultra-precision motion control system.