A 0.18-μm CMOS Low-spurious Local Signal Generator for MB-OFDM UWB Radio

This paper presents a new single PLL and single SSB-mixer architecture for a local signal generator of the Mode-1 MB-OFDM UWB systems. Using a VCO running at 8976 MHz and a divide-by-2 circuit, it can provide a 4488-MHz carrier signal with low-spurious levels, which is required to meet the spectrum mask requirements being considered in Japan and Europe. A divide-by-8.5/17 circuit using double-edge triggered operation is introduced to obtain 3432-and 3960-MHz carriers from the same VCO in order to save die area. This circuit generates 1056-and 528-MHz signals, and the required signals can be obtained by mixing these with 4488 MHz signal. The core area of the local signal generator fabricated in a 0.18-mum CMOS technology is 0.67 mm². The spurious levels for the 4488-MHz carrier are below -41 dBc.