ROM for Direct Digital Synthesizer

A project for ECE 547 "VLSI Design" - Spring Semester 2006
Department of Electrical and Computer Engineering
University of Maine

Designed by: Anusha Ramanujam

Direct digital synthesizer (DDS) plays an important role in modern digital communications for sine wave generation. This project involves designing a ROM for a DDS with an internal lookup table. My design involves a 256 bit ROM which stores the sinusoidal values for DDS. It consists of four 6 to 2⁶ bit tree decoders, four ROM’s and 2:1 multiplexers. The multiplexers select the right ROM and their outputs are latched using D flipflops.

This ROM receives 8 bit input from a 12 bit, 50 MHz accumulator designed by Aravind Reghu. The latched outputs are then fed to a 10 bit Digital to Analog converter designed by Steve Fortune. Cyrus Miller also worked on this project with me.

The project report contains a description of the project, details of the design and layout, and test results.