An important classification in this context is the methodology used in the process ASIC design [5]. The following three categories to describe it.
- static synchronous design: this first category is based on sensitivity of the flanks and database schemas time you single phase. All storage elements are sensitive to the wings of a common clock signal. If the clock stops, the whole system could be in a static state indefinitely, this design technique is also applied to programmable devices which are a very use of ASIC's for many systems. This is an important category because most of the systems designed today are built under this standard.
- Static multi Design: these circuits are based on a level detection system multiphase clock. Usually there are two phases of clock but there are cases where it will employ up to four phases. These designs have cascaded latch's which are sensitive to levels of a master clock, these are functionally equivalent to flip-flop's sensitive sides, only a simple modification is required to make the match is sensitive to the flanks . Multiphase levels are really desirable when the developed chip is the heart of the system, such as a microprocessor. The ASIC's are usually used as auxiliary chips in a system.
- dynamic multi Design: these dynamic circuits require their clock signals can be extended to maintain their status. This technique is used for propagation of the transistors, storage and pre-bus capacitance. It is the most advanced methodology.
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