In this article, I will share about HDL (Hardware Description Language) and Xilinx ISE simulator. HDL is used for design digital circuits. There are 2 type of HDL that commonly used, VHDL and Verilog. VHDL syntax is like Pascal language, while Verilog is like C language. HDL has differences with traditional programming language such as Pascal and C. In traditional programming language, all statements always executed sequentially. In HDL, there are statements that can be executed concurrently. HDL can be used for designing a digital ASIC or programming an FPGA.
FPGA (Field Programmable Gate Array) is consists of many basic digital circuit blocks. This circuit block is usually called LUT. FPGA can be used for implement flexible digital circuits, because FPGA is like microcontroller that can be programmed using a hardware programmer. On a FPGA, we can create any digital circuits from basic combinational circuits such as adder, decoder, multiplexer up to a complex system like a microcontroller. We can create a full function microcontroller such as AVR ATmega inside a FPGA. FPGA is also used for simulation when prototyping a digital IC before go to the custom ASIC development process. There are 2 commonly used FPGA, Altera and Xilinx. These FPGA has an IDE, for Altera is Altera Quartus and for Xilinx is Xilinx ISE.
ASIC (Application Specific Integrated Circuit) is an IC that has a specific function (not flexible like FPGA). ASIC can be an analog, digital, mixed-signal, or RF IC. The process of creating an ASIC is quite complex. The process is begin from the design, synthesis, routing, fabrication, and testing. This complete and detail process can be learned from microelectronics lecture. For your information, there are several software used for design ASIC such as Synopsys, MentorGraphics, and Cadence. These software are called EDA (Electronic Design Automation) software.
