Analyzes of VCO performances based on RF spiral inductors

This paper reports the theoretical study of two different passive RF inductors used to design a voltage-controlled oscillator (VCO) for wireless network at 5GHz The first inductor is designed using classic microelectronic technology with geometrical optimization and the second is made with etched silicon substrate. The obtained results show a high quality factor Qmax = 12.9 and Qmax=15.9 respectively for the first and second inductors. The self resonant frequencies are higher than 7.5 GHz and allow a large frequency excursion. Moreover, we have used TSMC RF CMOS 0.13 ßm technology and the ADS tool in order to design and analyze the responses of two different VCOs based on our RF spiral inductors. The obtained results show a slightly difference between two VCOs. Basically, the second inductor permits to ameliorate the power consumption and the tuning range of the VCO that reach: PC = 0.36 mW and TR = 16.6%. Nevertheless, the phase noise is considerably the same: PN = −102. 7dBc/Hz at 1 MHz of offset frequency.