Subharmonic direct frequency synthesizer for mode-1 MB-OFDM UWB system

This paper proposes a subharmonic direct frequency synthesizer (SH-DFS) for the hopping carrier generation in mode-1 MB-OFDM based UWB system. The SH-DFS employs octet phases of 2.244GHz from a VCO to synthesize and the deviations at 528MHz and 1.056GHz acquired from a divide-by-17 semi-dynamic divider. The output stage with the switched functionalities between a subharmonic single sideband (SH-SSB) mixer and an edge combiner generates the designated tone. Realized in 0.18-mu m CMOS technology, it occupies an active area of 1 x 1 mm(2). The chip draws 34mW power from a single supply at 1.8-V. The carrier output has the voltage swing larger than 700mV(pp) and the spurious tones are smaller than -20dBc.