A wide tuning range 2.2 to 2.8 GHz VCO with the phase noise enhanced techniques

This paper presents a low power voltage controlled oscillator (VCO) with the phase noise enhancement techniques. To reduce the phase noise of VCO, a bias filter consists of inductor and capacitor is used to suppress noise. Moreover, the source of tail current uses a memory reduced tail transistor to procure low power consumption and avoids degradation of phase noise. The Q-enhancement technique without cascading the cross-coupled MOSFET pairs is proposed. The wide tuning range is achieved by implementing the switch circuit that can adjust the value of capacitors. The VCO is designed and implemented by 0.18-μm TSMC CMOS process. The frequency tuning range is from 2.2-2.8 GHz. The current consumption is 1.5 mA with a 1.5-V power supply. The measured phase noise is -118 dBc/Hz at 1 MHz offset.