A 16-GHz Triple-Modulus Phase-Switching Prescaler and Its Application to a 15-GHz Frequency Synthesizer in 0.18- $\mu$ m CMOS

A triple-modulus phase-switching prescaler for high- speed operations is presented in this paper. By reversing the switching orders between the eight 45deg-spaced signals generated by the 8 : 1 frequency divider, the maximum operating frequency of the prescaler is effectively enhanced. With the triple-modulus switching scheme, a wide frequency covering range is achieved. The proposed prescaler is implemented in a 0.18-mum CMOS process, demonstrating a maximum operating frequency of 16 GHz without additional peaking inductors for a compact chip size. Based on the high-speed prescaler, a fully integrated integer-N frequency synthesizer is realized. The synthesizer operates at an output frequency from 13.9 to 15.6 GHz, making it very attractive for wideband applications in Ku-band. At an output frequency of 14.4 GHz, the measured sideband power and phase noise at 1-MHz offset are -60 dBc and -103.8 dBc/Hz, respectively. The fabricated circuit occupies a chip area of 1 mm² and consumes a dc power of 70 mW from a 1.8-V supply voltage