CPLD可编程逻辑芯片上实现信号发生器的方法和步骤，系统采用自顶向下的设计方法，以硬件描述语言VHDL和原理图为设计输入，利用模块化单元构建系统。-CPLD programmable logic chip Signal Generator methods and steps system uses top-down design approach to hardware descr iption language VHDL and principles of map design input,