Technical Research On Hardware Unit Of New Pattern Generator Controlled By DSP

Electron beam lithography machine is a large precise device used in research and development of microelectron industry and micro-fabrication .The pattern generator is a key unit of the above system. This paper is mainly about the interface realization of the pattern generator and design of the A/D and D/A converters.The interface of the pattern generator bases on the protocol of USB 1.1 in this paper. The paper introduces the protocol simply, then shows how to realize the software programming in the interface in detail.The design of A/D converter is studied in detail in the paper. Its core chip is AD9223 of ADI company, and the pre-amplifier, driving circuit and standard supply are designed according to the characteristic of backscattering signal in electron beam lithograph machine. The A/D converter has the following features: 1. the range of Vin(input voltage) is 0-2v; 2. its structure is simple and stable; 3. the interface is easy to control and has excellent extensibility.The designed D/A converter includes the main D/A, the rotation D/A, the displacement D/A, and the gain D/A. The core chip of the main D/A is DAC1146, while LTC1597 is the core chip of the other three D/As.