Four-Bit Serial Adder

1. Four-Bit Serial Adder By Huong Ho, Long Nguyen, Lin-Kai Yang Ins: Dr. David Parent Date: May 17th, 2004

2. Agenda • Abstract • Introduction • Project Details • Summary of Results • Conclusions

3. Abstract We designed an 4-bit serial adder that operated at 200 MHz and used of power 10.75mW and occupied an area of 192x60 um².

4. Introduction • Bit-serial structure is designed to process the input one bit at a time, generally using the results of the operations on the first bit to influence the processing of subsequent bits. • Because it passes all the bits through the same logic, bit-serial reduces a significant amount of required hardware. Typically, the bit-serial approach requires 1/nth of the hardware required for the equivalent n-bit parallel design. • Bit-serial structure reduces signal routing (1-bit signals instead of n-bit signals) and higher-speed operation (one adder and a register rather than an n-bit adder).

5. Introduction (cont.) • The price of this logic reduction is that the serial hardware takes n clock cycles to execute, while the equivalent parallel structure executes in one clock cycle. • Bit-serial architectures have been used successfully in many applications that are dealing with a bit stream such as signal processing, audio, video etc…. It was extremely popular in the 2-5u technology range.

6. 4-bit Serial Adder Schematic

7. Longest Path Calculations Note: All widths are in microns and capacitances in fF

8. D-Flip Flop Calculations

9. D-Flip Flop Schematic

10. D-Flip Flop Waveform

11. Full Adder Schematic

12. Full Adder Waveform

13. 4-bit Serial Adder Schematic

14. 4-bit Serial Adder Waveform

15. 4-bit Serial Adder Layout Area = 192 x 60 um²

16. Power Consumption P = 10.75 mW

17. DRC & Extraction

18. 4-Bit Serial Adder LVS

19. Summary of Results

20. Acknowledgements • Thank you Dr. Parent for being so patient!!! • Thanks to Cadence Design Systems for the VLSI lab. • Thanks to our classmates who helped us in the lab.