High-precision frequency synthesizers for UWB applications

Two closed-loop frequency synthesizers are proposed for multi-band OFDM alliance (MBOA) ultrawideband (UWB) application. Employing the technique of Miller divider, the first frequency synthesizer produces negligible in-band spurs while achieving less than 9.5-ns settling time. With delay-locked loop (DEL) operation, the second frequency synthesizer achieves a sideband magnitude of -35.3 dB and -82 dBc/Hz phase noise at the frequency offset of 400 Hz. Both UWB frequency synthesizers have been fabricated in 0.18-μm CMOS process and consumes only 22 mW and 54 mW, respectively.