부산대학교 도서관

The rapid development of the next-generation high-speed wireless communication system has set increasingly stringent requirements on the spectral purity of local RF oscillators. Low phase noise is crucial to support advanced modulation scheme enabling high data-rates wireless link [1]. A viable popular approach is to coupled N identical oscillators together to improve the phase noise by 10log 10 N at the cost of N times higher power [2]–[6]. Nevertheless, the coupling network needs to be designed carefully to avoid undesired multi-tone concurrent oscillations. Besides, area occupation is another issue of multi-core VCOs. The star-geometry as shown in Fig. 1. (bottom left), which is simple N times duplication of single core, occupies N times larger area so comes with an area penalty [3]–[5]. To solve this problem, circular geometry is proposed where the passives are merged into a single passive structure and the minimal realizable inductance is reduced while keeping a high Q factor [6]–[7]. In order to further reduce the silicon area, a square-geometry quad-core oscillator with inductor sharing technique is proposed in this paper and it exhibits a compact area of 0.09 mm 2 , which is the smallest quad-core VCO operating at a similar oscillation frequency. The unwanted mode is suppressed by the metal trace that connects the drain node of adjacent cores. Thanks to the proposed square-geometry and inductor sharing technique, the proposed quad-core class-F VCO can further reduce the area occupation. The proposed VCO is fabricated in 65nm CMOS technology. The measured phase noise is -137.2 dB/Hz at 10 MHz offset frequency from a carrier of 19 GHz, which translates to the FoM of 186.1 dBc/Hz.