Study Design X-band Quadrature VCO

The rapid growth in wireless communications and the development of CMOS technology have driven people to produce wireless transceivers at low-cost, low-power, compact size, and more-standards. At present, many radio frequency transceiver structures proposed at home and abroad (such as zero-IF transceiver) mostly require quadrature signals at high-purity and high matching. Therefore, the research of RF quadrature voltage controlled oscillator (QVCO) is of great significance. In this paper, we designed two new X-band quadrature-phase LC VCOs based on the CMOS technology, main contents and innovations are as follows:(1) The research background of VCO is introduced in this thesis, the working principle of LC cross-coupled VCO are summarized, meanwhile, the phase noise models of VCO are analyzed:linear time-invariance(LTI), linear phase time varying(LPTV), and the advantages and disadvantages of some topologies of common quadrature-phase LC VCOs are compared.(2) Implemented in TSMC0.18μm CMOS process, this study proposes a new capacitor-coupled QVCO based on two novel techniques:capacitor coupling and sinusoidal current biasing. The proposed QVCO had a frequency tuning range of9.4～10.5GHz and a phase noise of-90.47dBc/Hz@100KHz,-114.9dBc/Hz@1MHz from a carrier of10GHz while consuming3.5mW with1.5V voltage supply.(3) This article presents a new quadrature voltage-controlled oscillator (QVCO), which consists of two complementary cross-coupled voltage-controlled oscillators coupled via varactors. At the supply voltage of1.2V, the total power consumption is2.83mW. The free-running frequency of the QVCO is tunable from9.5GHz to10.4GHz as the tuning voltage is varied from0.0to1.2V. The phase noise is-88.98dBc/Hz@100KHz,-111dBc/Hz@1MHz at the oscillation frequency of10GHz.(4) The layout of QVCO was designed by Cadence and the post-layout simulation results show that the designed CMOS QVCOs both achieve design specification, also have good practicality and feasibility.