Research Projects

Sub-Nyquist Rate Digital-to-Analog Conversion for Cognitive Radio Transmitter

Stanley Yuan-Shih Chen, Nam-Seog Kim and Jan M. Rabaey

Gigascale Systems Research Center

The target of this project is to design a frequency-agile transmitter for TV band Cognitive Radio. The transmitter of the base station consists of Digital Waveform Synthesizer (DWS), Digital-to-Analog Converter (DAC), clock generation circuitry and the analog front end. The baseband waveforms with various modulation schemes are directly synthesized in digital domain. The transmission characteristics can be dynamically adapted and controlled in DWS. By utilizing the proposed sub-Nyquist rate conversion technique, the DAC converts the sampled digital waveforms into continuous-time analog waveforms and enhances image spectrum located in the target channels. A process-independent, fully-differential regulated Phase-Locked Loop (PLL) generates the low jitter clock for the whole transmitter. System-level simulation and analysis are implemented in Matlab. Critical circuit blocks will be implemented in 65nm CMOS technology.