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17268 Discussions

Logic Element

Altera_Forum
Honored Contributor II
‎09-02-2009 11:38 PM
1,584 Views

I have 1 design which use total of 734 logic element. When i want to optimize the design by doing chaining(remove one 32 bit register), the logic element used is 733. since 1 FF consists of 2 NAND or 2 NOR gate, 32 bit register will have 64 logic elements. The logic element used is 670 instead of 733. May i know the reason why? 

 

FYI, i use cyclone II. 

 

Thanks
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Altera_Forum
Honored Contributor II
‎09-03-2009 03:24 AM
627 Views

Well the term "logic element" is a bit fuzzy and truly is defined by the architecture. But specifically according to page 2-2 of the Cyclone II datasheet: 

 

http://www.altera.com/literature/hb/cyc2/cyc2_cii51002.pdf 

 

a LE consists of: 

--- Quote Start ---  

 

- A four-input look-up table (LUT), which is a function generator that  

can implement any function of four variables 

- A programmable register 

- A carry chain connection 

- A register chain connection 

- The ability to drive all types of interconnects: local, row, column,  

register chain, and direct link interconnects 

- Support for register packing 

- Support for register feedback 

--- Quote End ---  

 

 

Jake
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