Abstract:-This paper provides review of various wire length estimation techniques. Wire length plays an important role in the design of circuit. If wire length of the circuit is known before placement delay, resistance, power dissipation, and capacitance can be predicted. All these parameters play an important role in designing of the circuit. These parameters help in predicting the performance of the circuit in early design phase. Such estimations are very useful to optimize the circuits. This paper will provide a comparative analysis between different techniques which are used to predict the wire length.
Keywords:-channel, feed through, short nets, long nets.
Introduction:-As the technology size is shrinking we are moving from micron to …show more content…
In this design methodology two types of connections are defined:-
1. Channel:- if two cells being interconnected lie in the same row then space used for interconnecting is called channel.
2. Feed through :-if cells which are to be interconnected lie in different rows then space used for interconnecting is called feedthrough.
If technology having more than one metal layer is used then the channel are completely removed. Here two types of nets are defined:-
1. Short nets:- those nets whose fanout is less than 5 are called short nets.
2. Long nets:-those nets whose fanout is more than 5 are called long nets.
It is observed in a circuit maximum 10% of nets are long nets rest are short nets. First step in this methodology is to find the average width of the cell Using Avg width of the cells, the area of each cell given by area_cell is calculated as:-
Area_cell=width_avg *Hieght_cell
Total area of the layout can be now estimated as:-
Total_area=area_cell*num_cell
If the design is to be considered multilayer so there are no channels, it is also known also know that most of the nets are short nets so first we consider 2-pin nets:-
Estimation of long
Keywords:-channel, feed through, short nets, long nets.
Introduction:-As the technology size is shrinking we are moving from micron to …show more content…
In this design methodology two types of connections are defined:-
1. Channel:- if two cells being interconnected lie in the same row then space used for interconnecting is called channel.
2. Feed through :-if cells which are to be interconnected lie in different rows then space used for interconnecting is called feedthrough.
If technology having more than one metal layer is used then the channel are completely removed. Here two types of nets are defined:-
1. Short nets:- those nets whose fanout is less than 5 are called short nets.
2. Long nets:-those nets whose fanout is more than 5 are called long nets.
It is observed in a circuit maximum 10% of nets are long nets rest are short nets. First step in this methodology is to find the average width of the cell Using Avg width of the cells, the area of each cell given by area_cell is calculated as:-
Area_cell=width_avg *Hieght_cell
Total area of the layout can be now estimated as:-
Total_area=area_cell*num_cell
If the design is to be considered multilayer so there are no channels, it is also known also know that most of the nets are short nets so first we consider 2-pin nets:-
Estimation of long