Abstract:
Digital to analog converters (DACs) sit at the boundary of the digital and analog worlds, converting signals defined at discrete time instants to signals defined at a continuum of time instants. DACs are usually defined and specified as having a constant number of bits over a contiguous bandwidth and consume power which is proportional to 2^bits x bandwidth. Signals in practice frequently have an information or bit content which is not constant with frequency. Multicarrier systems which use bit loading to maximize information transmission through frequency selective channels are an example of this. As such, there is an opportunity to create a more efficient DAC design by shaping the bit resolution as a function of frequency based on the signal being converted. This work uses non constant information as a function of frequency to derive optimal DAC noise shapes given a power constraint and provides practical methods for realizing these noise shapes using delta sigma DACs.

Speaker Bio:
Zhenhua Yu received the B.S. degree in Information Engineering and M.S. degree in Communication and Information Engineering from Shanghai Jiao Tong University, Shanghai, China, in 2007 and 2010, respectively. He is currently working towards the Ph.D. degree in Electrical and Computer Engineering at Georgia Institute of Technology, Atlanta, GA. His research interests include OFDM, visible light communications, signal processing, and optimizations.