VHDL is a design tool that contains text editors, compilers,debuggers, and simulators. Within the last decade, It has become a powerful tool for engineers to design fully tested and reliable digital systems. There are two major Hardware Descriptive Languages in the current market, AHDL and VHDL. AHDL is Altera’s version of VHDL. Since Altera has a very supportive policy towards universities and colleges,educators may consider Altera’s MAX + PLUS I1 in their digital circuit design class. Beside digital circuit design,VHDL has also been used in digital filter design