Implementation of 5GHz current-reused VCO with linearity

In this paper, a linear tuning range, low power and low phase noise of current-reused voltage controlled oscillator (VCO) in a 0.18um CMOS process is presented. The core circuit of VCO is adopted dual-tuning capacitor with self-biased tail transistor structure. The proposed circuit is capable of lower circuit gain which can stable output frequency and improve phase noise, the tail current elimination circuit also improve the power dissipation. The measured result of bandwidth is from 5.2GHz to 6.3 GHz with a 19.1% tuning ratio by two tuning voltages. The phase noise of the proposed VCO is −119.9dBc/Hz at 1MHz offset frequency. The power consumption is 1.8mW from 1.4V supply and the Kvco exhibits the linearity with 200 MHz/V.