Electrical & Computer Engineering

Ramanujam

ROM for Direct Digital Synthesizer

Department of Electrical and Computer Engineering
The University of Maine
ECE 547, VLSI Design, Spring 2006

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 (PDF) contains a description of the project, details of the design and layout, and test results.