Design of Multi-Mode Frequency Synthesizer for System Level Clocking

AbstractThis paper describes the design of a multi-mode frequency synthesizer. The oscillation frequency of VCO is 5GHz, and the reference clock accepts 18-39MHz. A multi-mode controller which contains triangular wave generator, 3rd order Sigma-Delta modulator, programmable divider, etc, is proposed in this paper. The measurements show a less than 58dB spur, the spectrum spread about 4700ppm and the EMI is reduced about 22dB. This circuit consumes 28mW power at 1.2V power supply and is manufactured in 0.13um CMOS process