VHDL Design Styles

VHDL is a hardware description language that permits the designers to design a design in either Bottom-up or Top-down methodology.

1.   Bottom-Up Design

The traditional method of electronic design is bottom-up. Each design is performed at the gate-level using the standard gates. With increasing complexity of new designs like ASICs, Microprocessors, etc, this approach is nearly impossible to maintain due to high complexity i.e., thousands of transistors are used to make the design. These traditional bottom-up designs are used to develop new structural, hierarchical design methods.

2.   Top-Down Design

The desired design-style of all designers is the top-down design as it offers advantages like early testing, easy change of different technologies, a structured system design, etc.

But it is very difficult to follow a pure top-down design. Due to this fact most designs are mix of both the methods, implementing some key elements of both design styles.