A Current-reused VCO with Degenerated RC Components

In this paper, we presents a current-reused voltage-controlled oscillator which consists of one nmos transistor and one pmos transistor. The voltage controlled oscillator (VCO) is designed for 2.45 GHz operation. The study is based on the TSMC 0.18-um CMOS processes. The degeneration source resistors are used to improve magnitude symmetry of output signals. Additional source capacitors which are parallel with source resistors are used to improve phase noise. Measurement results show -94.6 and -116 dBc/Hz at 100-kHz and 1-MHz offset, respectively, when the oscillation frequency is at 2.45 GHz. In this work, the core current is 0.35 mA from a 1.8-V supply. The tuning range is from 2.24 to 2.52 GHz under the tuning voltage between 0 to 2 V.