2.49–4.91 GHz wideband VCO with optimised 8-shaped inductor

A wideband low-phase noise VCO is proposed for multi-standard wireless communication system. An 8-shaped high-Q inductor is employed to enhance the performance of the VCO. The frequency pulling is reduced by using the 8-shaped coil. Implemented in a 180 nm CMOS process, the VCO can provide a very wide tuning range of 65.4% from 2.49 to 4.91 GHz. A phase noise lower than −121.25 dBc/Hz is obtained at 1 MHz offset over the whole working band while the current consumed varies from 3.5 to 8.7 mA.