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8-Bit ALU. Kin Fu Tang Robert Last Joseph Roosma Adnan Alam Advisor: David W. Parent May 8, 2006. Agenda. Abstract Introduction Purpose Simple Theory Summary of Results Project (Experimental) Details Results Cost Analysis Conclusions. Abstract.
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8-Bit ALU Kin Fu Tang Robert Last Joseph Roosma Adnan Alam Advisor: David W. Parent May 8, 2006
Agenda • Abstract • Introduction • Purpose • Simple Theory • Summary of Results • Project (Experimental) Details • Results • Cost Analysis • Conclusions
Abstract • An 8-bit ALU using a Han-Carlson carry network was designed. It was shown through simulations to operate at a clock frequency of 200MHz, using 25.28mW of Power and requiring an area of XxX mm2
Introduction • An ALU is an important building block in digital systems which carries out the basic arithmetic and logic. • Depending on the supplied control signals, the ALU is designed to carry out the following operations on two 8-bit numbers: ADD, SUB, AND, OR, XOR, NAND, NOR, and many others.
Block Diagram 8-bit Input DFF AOI3333 (G, HS) Control Signals (ADD, OR, etc.) Han-Carlson Carry Network XOR DFF 8-bit Output
Summary of Results • Determination of Gate Widths • Final schematic, and • Simulations: NC Verilog and SPICE • Final layout • Verification of layout and extraction.
Schematic - Overall LONGEST PATH DFF INVERTER P G AOI3333 HAN-CARLSON NETWORK XOR BLACK CELL DFF
Simulation – SPICE – Worst Case (Schematic) τPLH3.76ns
Simulation – SPICE – 2-bit Addition(Schematic) Output Input
Simulation – SPICE – Power Usage(Schematic) P = 25.28mW
Layout - Overall DFF AOI3333 HAN-CARLSON NETWORK XOR DFF
Cost Analysis • Estimated time spent on each phase of the project: • Verifying logic: 8 hours • Verifying timing: 10 hours • Layout: 45 hours • Post extracted timing: 8 hours ___________TOTAL: 71 hours
Lessons Learned • Start early. • Make sure that the overall logic works first (with actual transistors). • Once the overall timing is agreed upon, it’s hard to go back and make changes. • Use cell based design, it’s less confusing. • Save time for troubleshooting.
Summary • An 8-bit ALU which operates at a clock frequency of 200MHz was designed and simulated. • All specifications (clock and power) were met.
Acknowledgements • Dr. David Parent • Cadence Design Systems • Irma Alarcon (Lab Technician)