A Fully Integrated Sub-GHz Inductor-less VCO with a Frequency Doubler

This paper presents an inductor-less voltage-controlled oscillator (VCO) with active inductors (AIs) for wideband applications and is also applicable to different wireless technologies. Both the AIs and the VCO are designed in a 65-nm CMOS technology. The fundamental frequency covers a frequency band from 129 MHz to 442 MHz. The output of a frequency doubler is exactly two times that of the fundamental frequency. Both the fundamental and doubled frequency can be output at the same time with an excellent synchronization performance. The optimal phase noise of this design is about −112 dBc/Hz@1 MHz offset. Moreover, it achieves an excellent figure of merit (FOM) at −170 dBc/Hz with a total power consumption less than 6.2 mW. The footprint of the core area is only $0.044\times 0.092$ mm 2 .